KR19990022469A - Timing adjustment control for efficient time division duplex communication - Google Patents

Abstract

Provided is a time division duplex communication system over a single frequency band in which the guard time overhead is reduced by actively adjusting the reverse link transmission timing as a round trip propagation delay function. In response to the polling message from the base station, the user station searching for communication settings sends a response message. The user station calculates the distance of the user station by measuring the propagation delay for reception of the response message using the propagation delay calculator 812, and the timing controller 806 and the transmitter 807 advance or adjust the timing of the user station. Send a timing adjustment instruction to delay to the user station. The base station then monitors the user station transmissions and periodically instructs the user station to adjust the user station timing in the same manner. The user station transmits a control preamble at the beginning of each time slot to allow the base station to perform round trip timing calculation and user station power adjustment or antenna selection.

Description

Timing coordination control for efficient time division duplex communication

The continuing demand for flexible mobile communications has necessitated the development of a variety of techniques for allocating available communications bandwidth to a growing number of cellular service users. Two conventional techniques for allocating communication bandwidth between a cellular base station and a set of cellular user stations (also called mobile stations) are frequency division duplex (FDD) and time division duplex (TDD).

In this specification, FDD refers to a technique for establishing full duplex communication having both forward and reverse connections with separated frequencies. And, TDD refers to a technique for establishing full duplex communication with both forward and reverse connections occurring at the same frequency but separated in time to avoid collisions. Other communication techniques include time division multiple access (TDMA) that is separated in time to avoid collisions of transmissions by multiple users, and frequency division multiplexing that is separated in frequency to avoid collisions of transmissions by multiple users. There is access (FDMA), and time division multiplexing (TDM) in which multiple data streams are time multiplexed together on one carrier. Various combinations of FDD, TDD, FDMA, and TDMA may be used.

In certain FDD techniques, the base station is assigned a set of frequencies for transmission, using different frequency slots for each user station. Each user station is then assigned a different frequency for transmission to the base station. For each new user that communicates with the base station, a new pair of frequencies is needed to maintain the communication connection between the base station and the new user station. Thus, the number of users that can be supported by one base station is limited by the number of available frequency slots.

In certain TDD techniques, the same frequency is used for all user stations communicating with a particular base station. Interference between user stations can be avoided by having the user stations transmit at different times. This is done by dividing the time into such a plurality of time frames, where each time frame consists of a plurality of time slots. Typically, a base station communicates with only one user station during a time slot and sequentially with all user stations during different time slots within one time frame. Thus, the base station communicates with a particular user station during each time frame.

In one variation of the described system, the base station is assigned a first portion of each time slot that the base station transmits to a particular user station. The user station is then assigned a second portion of the time slot in which the user station responds to the base station. Thus, the base station may sequentially communicate with all user stations during a particular time frame a manner of transmitting to the first user station, waiting for a response, and after receiving a response from the first user station, to the second user station. Continue until.

Time division duplexes have an advantage over FDD or TDD, which require the use of only one frequency band width. However, a drawback of many conventional TDD or TDMA systems is that their efficiency decreases as the cell size increases. The decrease in efficiency is due to the relatively unpredictable nature of the propagation delay of the transmission from the base station to the user station over the air channel and the transmission from the user station to the base station over the air channel. Since the user station moves frequently and can move anywhere within the cell radius that the base station is responsible for, the base station generally does not know in advance how long a propagation delay will take in communication with a particular user station. To prepare for the worst case, conventional TDD systems typically have a round-trip guard time to ensure that communication with the first user station is completed before initiating communication with the second user station. Will provide). Since the round trip protection period is present in each time slot regardless of how far or how close the user station is, the necessary round trip protection period will add significant overhead, especially in large cells. This additional overhead will limit the number of users, which in turn will limit the efficiency of the TDD system.

1 shows the basic round trip timing for a TDD system from the perspective of a base station. The polling loop 101, ie, the time frame, for the base station is divided into a plurality of time slots 103. Each time slot 103 is used for communication from a base station to a particular user station. Thus, each time slot includes base station transmission 105, user transmission 107, and delay time 106. Here, the delay time 106 includes a delay time for the base station transmission to propagate to the user station, a delay for the user station to process and generate the response user transmission 107, and a delay for the user transmission 107 to propagate to the base station. Time is included.

If the user station is located next to the base station, the base station can expect to respond from the user station immediately after finishing transmission and switching to the receive mode. As the distance between the user station and the base station increases, the time for the base station to wait for a response increases. The base station cannot hear a response from the user station immediately and must wait until the signal propagates to the user station and also returns.

As shown in FIG. 1, within the first time slot 110, the user transmission 107 is sent to the base station at approximately the same time as the distance from the end of the base station transmission 105 to the user transmission 107. To reach. This indicates that the user station is located about half the cell radius from the base station. In the second time slot 111, the user transmission 107 appears very close to the end of the base station transmission 105. This indicates that the user station is very close to the base station. In the third time slot 112, the user transmission 107 appears immediately at the end of the time slot 112. This indicates that the user station is at or near the cell boundary. Since the third time slot 112 corresponds to a user station at the maximum communication distance for a particular base station, the delay 106 shown in the third time slot 112 is the maximum round trip propagation time, and therefore, the maximum. Round trip protection time.

Although shown in FIG. 1 for simplicity, in addition to the propagation delay time, a delay will occur in switching between the reception mode and the transmission mode at the user station, the base station or both. A typical transmit / receive switch time is about 2 microseconds, but additional allocations may be made to account for channel rigning effects associated with multiple paths.

As the cell size increases, the TDD protection period must be increased in consideration of the longer propagation delay. In such cases, the guard period occupies a significant portion of the available time slots for shorter round trip frame periods. The percentage increase in waste time due to overhead is because the TDD protection period is a fixed length determined by the cell radius, while the actual round trip frame period varies with the distance of the user station. Therefore, as the cell grows, more time is wasted on overhead in the form of a guard period than on the actual transmission of information between the user station and the base station.

One conventional TDD system is a digital European wireless communication system (DECT) developed by the European Telephone Standards Organization (ETSI). In a DECT system, the base station transmits a long burst of data segmented into time slots. Each time slot here has data associated with a particular user station. After the guard period, the user station responds within a contiguous time slot of the designated group in the same order that the base station sent the data to the user station.

Another system currently in use is the Global System for Mobile Communications (GSM). 4 shows a timing pattern in accordance with certain existing GSM standards. According to these standards, communication between a base station and a user station is divided into eight burst periods 402. The base station may communicate with up to eight user stations, one within each burst period 402.

The GSM standard requires two separate frequency bands. The base station transmits at the first frequency F _A , while the user station transmits at the second frequency F _B. After the user station transmits the base station transmission 405 on the first frequency F _A during the particular burst period 402, the user station shifts by 45 MHz to the second frequency F _B , resulting in approximately three burst periods 402. After this, user transmission 406 is initiated in response to base station transmission 405. The delay by three burst periods is considered large enough to be responsible for the delay between the base station and the user station.

It is important in a GSM system that the user transmission 406 received at the base station fits within the appropriate burst period 402. If not, the user transmissions 406 from the user stations using the adjacent burst period 402 may overlap, resulting in a loss of transmission quality or a complete loss of communication due to interference between the user stations. Thus, each burst period 402 is surrounded by a guard period 407 to account for the uncertain signal propagation delay between the base station and the user station. By comparing the expected reception time with the time of the signal actually received from the user station 302, the base station may instruct the user station to advance or delay its transmission timing to enter the appropriate burst period 402. This is known as adaptive frame alignment. The specification related to adaptive frame alignment for GSM systems is TS GSM 05.10.

The drawback of the described GSM system is that this system requires two separate frequency bands. Also, having a relatively rigid structure, its flexibility or adaptability to any cellular environment may be limited.

Another system currently in use is the Wide Area Coverage System (WACS). This system is a narrowband system that uses the characteristics of both FDMA and TDMA. In WACS, as in GSM, two distinct frequency bands are used. One frequency band is used for user station transmission and another frequency band is used for base station transmission. The user station transmission is offset by 1/2 of one time slot from the corresponding base station transmission to allow propagation time between the base station and the user station. The standard WACS does not support spread spectrum communication (a known type of communication in which the bandwidth of the transmitted signal does not exceed the bandwidth of the data to be transmitted) and has an overall structure characterized by being relatively strict.

In many systems, the channel structure is a structure in which a user station receives information on another channel while sending a response to a base station. The ability to simultaneously transmit and receive requires the use of diplexers, which are relatively expensive components for mobile handsets.

Especially in large cells, it is advantageous to provide a flexible system that has the advantages of time division duplex communication but does not have the overhead of a full round trip protection period within every time slot. It is more advantageous to provide such a system that requires only one frequency band for communication. It is further advantageous to provide a TDMA or TDMA / FDMA system in which the user station does not need to be coordinated with the diplexer. It is further advantageous to provide a time frame structure that can be used in a variety of communication environments and that is readily adaptable to one or multiple frequency bands.

<Summary of invention>

One feature of the present invention provides a means for performing time division multiplexing communication, particularly in large cells.

In one embodiment, in the first portion of the time frame, the base station starts a continuous base station transmission to each communication user station. One collective guard period is allocated while the base station waits for a response from the first user station. Next, the user stations have a minimum guard period between each reception and respond one by one in time slots on the same frequency as the base station. To prevent interference between user transmissions, the base station instructs user stations to accelerate or slow their transmission timing.

To initiate communication between the base station and the user station, each base station transmission may include a header indicating whether a slot pair is occupied. If the slot pair is empty, the user station responds with a simple message at the designated part of the slot pair. The user portion of the slot pair includes the full round trip protection time allocation to account for the uncertain distance between the base station and the user station in the initial communication. The actual reception time of the user transmission is compared with the expected reception time to determine how far away the user station is. In subsequent time frames, the base station may speed up or slow down its timing, if necessary, so that the entire information message can be transmitted without interference between user stations.

In another feature of the invention, base station transmissions alternate with user transmissions on the same frequency. The base station and the user station may proceed with main data transmission with a preamble, for example, as necessary to perform synchronization or spread spectrum control of spread spectrum communication signals. The preamble may be transmitted at specified time intervals between two data transmissions. The base station may instruct the user station to accelerate or slow down its timing based on the calculated round trip delay time.

In other embodiments of the present invention, multiple frequency bands are used. For example, one frequency band may be used for base station transmission and another frequency band may be used for user station transmission. Reverse-links user station transmissions are offset by a predetermined amount from base station transmissions. The base station and the user station may transmit the preamble prior to the time slot designated for primary data transmission, and may interleave the preamble at specified time intervals between two different time slots. The preamble consists of a plurality of bursts, one from each of the different antennas, to allow channel sounding to the target. The base station may instruct the user station to accelerate or slow its timing based on the calculation of the round trip propagation delay time.

In another aspect of the present invention, a general frame structure is provided that can be used in both TDMA and TDMA / FDMA systems. Appropriate frame structures using ranging capabilities may be constructed from timing elements, including preparatory measures for data transmission, preambles, guard periods, and the like. The frame structure can be made suitable for operation in various embodiments of a high tier or low tier environment by selecting an appropriate combination of general timing elements.

The dual mode base station architecture is provided with multiple frequency band operating capabilities. The base station has the advantage of a low IF digital correlator design.

Further modifications, applications, and details of the above-described embodiments are disclosed herein.

TECHNICAL FIELD The present invention relates to communications, and more particularly to air interfaces and protocols suitable for use in cellular communication environments.

1 is a diagram illustrating basic round trip timing from a base station perspective in a prior art TDD system.

2 is a graph showing the round trip protection period as a percentage of the actual round trip frame period in the prior art TDD system of FIG.

3A and 3B are diagrams of a cellular environment for communication.

4 is a timing pattern diagram in accordance with the existing GSM standard.

5A is a basic round trip timing diagram of a TDD / TDM / TDMA system from a base station perspective in accordance with one embodiment of the present invention.

5B is a timing diagram illustrating an initial communication connection between a base station 304 and a user station 302. FIG.

FIG. 5C is a timing diagram illustrating a variant of the TDD / TDM / TDMA system of FIG. 5A using an interleaved transmission format. FIG.

5D is a chart comparing the performance of the system of FIG. 5A without forward error correction and the performance of the system of FIG. 5A with forward error correction.

FIG. 6 is a graph showing the round trip protection period as a percentage of the actual round trip frame period in the embodiment of FIG. 5A.

7 illustrates an alternative timing protocol for reducing the total round trip protection period.

8A is a hardware block diagram of a base station in accordance with an embodiment of the present invention.

8B is a hardware block diagram of an alternative embodiment of a base station.

9 is a hardware block diagram of a user station in accordance with an embodiment of the present invention.

10A is a timing diagram in accordance with another embodiment of the present invention, and FIGS. 10B-10E are diagrams of a time frame structure expressed in terms of the timing sub-elements of FIG. 10A.

11A is a diagram of a timing sub-element in accordance with another embodiment of the present invention, and FIGS. 11B-11D are diagrams of a time frame structure expressed in terms of the timing sub-element of FIG. 10A.

12-12C are good message format tables for base station and user station transmissions.

13A-13B are diagrams illustrating the structure of connected preambles, and FIG. 13C is a chart comparing the performance of the preamble, and FIGS. 13D-E are charts comparing the preamble performance using matched and unmatched filters, respectively. .

14-17 are charts comparing various performance features of a high tire and low tire air interface including selected features of the embodiments described herein.

18 is a block diagram of a low IF digital correlator.

FIG. 19A is a block diagram of a dual mode base station operable at multiple frequencies with both spread spectrum and narrow communication, and FIG. 19B is a chart showing selected frequencies and other parameters for use in the dual mode base station of FIG. 19A.

One feature of the present invention is that it provides an efficient means for performing time division duplex communication and is suitable for large cell environments. Embodiments of the present invention have the advantage of spread spectrum communication techniques such as, for example, code division multiple access (CDMA) techniques in which communication signals are encoded using pseudo random number coding sequences, and the communication signals span different frequencies. It can be used in conjunction with multiplexed frequency division multiple access (FDMA) and in combination with CDMA, FDMA, or other combinations of communication technologies.

3A is a diagram of a cellular environment for a communication system having a base station and a user station.

In FIG. 3A, a communication system 301 for communication between a plurality of user stations 302 includes a plurality of cells 303, each having a base station 304, typically located at the center of the cell 303. Each station (both base station 304 and user station 302) generally includes a receiver and a transmitter. User station 302 and base station 304 may communicate using any other communication technique or time division duplex disclosed herein.

3B is a diagram of a cellular environment in which the present invention may operate. As shown in FIG. 3B, area 309 is divided into a plurality of cells 303. Each cell 303 is associated with an assigned frequency F1, F2, or F3 and an assigned spread spectrum code or code set C1 through C7. In order to minimize interference between adjacent cells 303, in the preferred embodiment, three different frequencies F1, F2, and F3 have any two adjacent cells 303 with the same assigned frequency F1, F2, or F3. It is allocated not to have.

To further reduce the possibility of intercell interference, different orthogonal spread spectrum codes or code sets C1 to C7 are assigned as shown in adjacent clusters 310. Although seven spread spectrum codes or code sets C1 to C7 that are convenient to form a 7-cell repeating pattern are shown in FIG. 3B, the number of spread spectrum codes or code sets varies depending on the particular application. For additional information regarding specific cellular communication environments, see US Patent Application No. 07 / 682,050, entitled Three Cell Wireless Communication System by Robert C. Dixon, and PCS Pocket Phone / Mocrocell Communication Over-Air Protocol, by Gary B. Anderson et al. US Patent Application No. 08 / 284,053 to the title. Each of these patent applications is incorporated herein by reference.

The use of spread spectrum for carrier modulation is not a requirement for practicing the present invention, but when used in the cellular environment of FIG. 3B, to assign different carrier frequencies F1, F2, and F3 to adjacent cells 303 It allows a very efficient frequency reuse factor with N = 3. Interference between cells 303 using the same carrier frequency F1, F2, or F3 results in propagation loss due to the distance separating the cells (any two cells 303 using the same frequency F1, F2, or F3 between each other). Smaller than two cells 303 in distance], and by spread spectrum processing gain of cells 303 using the same frequency F1, F2, or F3. Additional interference isolation is provided through CDMA code division. TDD or TDMA communication technology may be used in conjunction with the cellular technology of FIG. 3B.

In a preferred embodiment of the present invention using time division duplex, the same frequency F1, F2, or F3 is used for all user stations 302 communicating with a particular base station 304. Interference between the user stations 302 is avoided by allowing different user stations 302 to transmit when they are not at the same time or at the same time as the base station. Base station 304 is assigned a first portion of a time slot during base station 304's transmission to a particular user station. Each user station 302 is then assigned a second portion of the responding time slot. Thus, the base station 304 transmits to the second user station 302, waits for a response, receives a response from the first user station 302, and then transmits to the second user station 302. Do it.

As mentioned above with respect to FIG. 1, due to the mobility of the user station 302, a base station 304 over a public channel from a user station 302 or a transmission from a base station 304 over a public channel may be used. The propagation delay time of the transmission to) is unpredictable. Thus, the base station 304 generally cannot know in advance how long a propagation delay will take in communicating with a particular user station 302. To prepare for the worst case, conventional TDD systems provide a round trip protection period within each time slot, which is before communication with the first user station 302 initiates communication with the second user station 302. To ensure that it is done.

Typical round trip protection period is 6.7 microseconds per kilometer of cell radius. Thus, for a cell 303 of 3 kilometers radius, a round trip protection period of 20 microseconds is required. In conventional systems, a round trip protection period is applied to each time slot 103 regardless of how far user station 302 is from base station 304. Thus, the required round trip protection period results in time overhead in such conventional systems and limits the number of users.

As the cell size increases, the TDD protection period must increase against longer delay times. The relationship between the cell radius and the protection period can be set as follows.

TDD protection period = 2 × (cell radius) / (light speed)

FIG. 2 shows the round trip protection period for the conventional TDD system as shown in FIG. 1 in terms of the actual round trip distance frame period (i.e., the amount of time actually needed for the base station 105, propagation delay time 106, and user). It is a graph expressed as a percentage of the transmission 107. 4 microseconds were added for the transmission / reception switching time, while the TDD protection period is a fixed length determined by the cell radius, while the actual round trip time is the user station 302. As the cell radius increases, more time is wasted on overhead in the form of a guard period, rather than the actual transmission of information between the user station 302 and the base station 304, as the cell radius increases. The efficiency of conventional TDD systems, especially those with large cells, is degraded as a result of the round trip protection time.

5A illustrates the basic round trip time of a TDD / TDM / TDMA system from a base station perspective to reduce the overall round trip protection time in accordance with one or more aspects of the present invention.

In FIG. 5A, the time frame 501 is divided into a transmitter 502, an integrated guard time 503, and a receiver 504. The transmitter 502 includes a plurality of transmission time slots 510. The receiving unit 504 includes a plurality of receiving time slots 504.

In the transmitter 502, the base station 304 transmits to the user station 302 one for each transmission time slot 510 of the transmitter 502 of the time frame 501. During the unified protection time portion 503, the base station 304 waits for the last base station transmission from the last transmission time slot 510 to be received by the appropriate user station 302, and the first user station transmission is sent to the user station 302. Wait for it to arrive. At the receiver 504 of the time frame 501, the base station 304 receives one user station transmission for each received time slot 511 of the receiver 504 of the time frame 501.

A particular transmit time slot 510 and corresponding receive time slot 511 may be considered to collectively include dual time slots similar to the time slots 110, 111, and 112 shown in FIG. 1. Although there are eight time slots 510 and 511 shown in FIG. 5A, more than eight or less than eight time slots 510 and 511 may be used if needed for a particular application.

The base station 304 preferably sends a message to the user station 302 and receives a message from the user station 302 once in a dual communication manner once during each time frame 501. In one embodiment of the present invention, user station 302 receiving base station transmission from first transmission time slot 510 is a first user station transmitting response user station transmission in first receiving time slot 511, User station 302 receiving base station transmission from second transmission time slot 510 is a second user station transmitting a response user station transmission in second receiving time slot 511. In this manner, base station 304 transmits a series of consecutive base station transmissions, each of which is directed to an individual user station 302 and receives a series of consecutive base station transmissions in a matching return order.

The user station 302 may respond in the same order as the base station transmission, but otherwise the base station may include a command in the header or may instruct the specific user station 302 to respond at a different location.

The integrated protection time portion 503 of the time frame 501 is essentially a single integrated dwell time while the base station 304 is waiting for a response from the first user station 302. The integrated protection time section 503 needs to ensure that base station transmissions in the final transmission time slot 510 arrive at the desired user station 302, which may be located around the cell before the first user station 302 responds. have. If the first user station 302 can respond before expiration of the unified protection time portion 503, the transmission may interfere with the final base station transmission. Therefore, the integrated protection time portion 503 needs to be about the same length as the delay 106 shown in the third time slot 112 of FIG. 1, and as mentioned, the maximum round trip protection time of the system of FIG. Indicates. However, unlike the system of FIG. 1, in the embodiment of FIG. 5A only one maximum round trip protection time (ie, integrated guard time 503) is required.

It should be noted that there is some delay time for the base station 304 and the user station 302 as in the system of FIG. 1 to switch from transmit mode to receive mode, or from receive mode to transmit mode. These delays are nearly 2 microseconds for each switching operation. Unlike the conventional system of FIG. 1, the base station needs to switch modes in each time slot 103, and the base station 304 of the embodiment of FIG. 5A receives from a transmission mode in a given time frame 501. It may be necessary to switch to mode and vice versa. Unlike the system of FIG. 1, where the base station must wait for the user station to switch from the receive mode to the transmit mode in each time slot 103, the first user station 302 responding in the time frame 501 of the embodiment of FIG. 5A. ) Potentially adds a receive / transmit switching delay to the system.

In the embodiment of FIG. 5A, the timing structure is preferably organized so that messages between user station-base stations from user station 302 arriving at base station 304 during receiver 504 do not overlap. When each user station 302 starts reverse link transmission at a certain offset from the time of forward link data reception according to the time slot number, duplicate messages and final disturbances sometimes appear by the base station 304. To prevent such interference of user station transmission inputs, each user station 302 biases transmission start timing as a function of its bidirectional propagation time to the base station 304 as described below. Thus, the reverse link messages are not reached in sequence and arrive at the receiving portion 504 of the time frame 501 at the base station 304. A brief guard band 512 is provided between each pair of receive time slots 511 to allow timing error and channel ringing. This brief guard band 512 is considerably shorter than the maximum round trip protection time 106 as described for FIG. 1.

In order to bias the transmission start timing, in the preferred embodiment the base station 304 is equipped with means for determining the round trip propagation delay to each user station 302. Round trip timing (RTT) measurements are preferably accomplished as a cooperation between the base station 304 and the user station 302, and thus include a communication transaction between the base station 304 and the user station 302. RTT processing may be performed upon initial communication setup between the base station 304 and the user station 302, and then periodically as needed. The measured round trip time from the RTT treatment may also be the averaged transient time.

In the RTT process, the base station 304 transmits an RTT command message instructing the user station 302 to resend a short RTT reply message after a predetermined delay period ΔT after reception. The predetermined delay period ΔT may be transmitted as part of the RTT command message or preprogrammed as a system variable. The base station 304 measures the time for receiving the RTT reply message. The base station 304 then calculates a propagation delay to the user station 304 based on the time for transmitting the RTT command message, the predetermined delay period ΔT and the time for receiving the short RTT reply message.

Once the propagation delay to the user station 302 has been calculated, the base station 304 notifies the user station 302 of the propagation delay measured in the RTT process or provides a bias time message that provides a specific timing adjustment command. To transmit. User station 302 then timings the transmission based on the information contained in the bias time message. Once the timing is set in such a manner, the base station 304 may instruct the user station 302 periodically to maintain the allocated reverse link TDMA time slots by preceding or delaying the transmission timing. The mechanics of adjusting the timing in response to the timing adjustment command may be similar to the techniques conventionally used in the GSM system described generally outside the present specification. Timing adjustment command control may be performed according to the technique described, for example, in the GSM specification TS GSM 05.10, which has been described in its entirety herein but was used by reference. After the response from the user station 302 is received at the base station 304, the base station 304 adjusts the user station transmission time as often as each time frame 501 if necessary, thereby closing the timing of the user station 302. Loop control can also be maintained.

For precise timing measurement in the RTT process, communication between the user station 302 and the base station 304 is preferably performed using a direct sequence spread spectrum modulation form. Other formats may be used, but the RTT measurement is less precise, resulting in a wider allowance for the omitted guard band 512 for timing of errors in the user station 302 transmission.

FIG. 5B is a timing diagram illustrating an example of an initial communication link-up between a base station 304 and a user station 302 according to the system of FIG. 5A. To facilitate initial communication between the base station 304 and the user station 302, each base station transmission during the transmission time slot 510 may include a data link message indicating whether a particular slot pair 510, 511 is available. 551 may have a concise header 550 before. If slot pairs 510 and 511 are available, user station 302 that needs to establish communication with base station 304 may have a concise reply message 562 in receive time slot 511 of slot pairs 510 and 511. Answer The receiving time slot 511 should have a minimum duration of the total round trip protection time and the length of the acknowledgment message 562 so that the initial maximum distance between the base station 304 and the user station 302 in communication is uncertain.

The base station 304 compares the real time of the response message 562 with the expected time of reception to determine how far apart the user station 302 is. In the subsequent time frame 501, the base station 304 may instruct the user station 302 to precede or delay the timing required for the entire length of the information message to be sent to the user station 302 without interruption.

Now, the timing protocol shown in FIG. 5B will be described in detail. The user station 302, which needs to establish communication with the base station 304, listens to the header 550 sent from the base station 304 at the beginning of each transmission time slot 510. If the user station 302 detects a header 550 that includes a status message indicating that the corresponding time slots 510, 511 are not available or occupied, the user station 302 attempts to respond to an acknowledgment message. do. The header 550 may include a bit that defines the delay time ΔT and indicates to the user station 302 which responds a predetermined delay time that should be transmitted upon response. The delay time ΔT may be measured for various references, but is preferably measured relative to the start of the corresponding receive time slot 511. The user station 302 preferably includes means for tracking the relative position and timing of the time slots 510 and 511 (timers and / or counters, etc.) in order to respond correctly.

In one embodiment of FIG. 5B, the delay time ΔT represents the relative delay time measured from the start of the appropriate receive time slot 511. An exploded view of receive time slot 511 is shown in FIG. 5B. In an appropriate receive time slot 511, user station 302 is delayed for a delay time DELTA T before sending reply message 562. The delay time ΔT may be used by the user station 302 for error processing or another internal household task. As FIG. 5B is shown from a perspective view of a base station 304 waiting to receive an acknowledgment message 562, the base station 304 is configured to allow the user station 302 to respond to the acknowledgment message 362 until the actual reception time of the acknowledgment message 362. Find the propagation time from the time of transmission. By measuring the time difference between the end of delay time ΔT and the start of response message 562, base station 304 confirms propagation delay 561.

Therefore, the reply message 562 may provide the RTT reply message function described above, and the base station 304 measures the propagation delay 561 upon receiving the reply message 562 to set an appropriate timing for the user station 302. Check it.

Once the propagation delay 561 is determined, the base station 304 can instruct the user station 302 to precede or delay the timing by a desired amount. For example, in the exemplary system of FIG. 5B, the base station 304 may prioritize the timing by the same time as the propagation delay time 561 so that the user station 302 is essentially transmitted at the far end of the brief guard band 512. The user station 302 may be instructed. Therefore, if the user station 302 is within the maximum range, the timing advance command is set to zero (not including the delay time ΔT and not represented in the user station transmission). In contrast, if the user station 302 is very close to the base station, the timing advance command is set to approximate the total guard time provided (ie, the maximum propagation delay time). The timing advance command may be represented as the number of bits or chips so that the user station 302 responds by preceding or delaying the timing by the specified number of bits or chips. Otherwise, the timing advance instruction may be represented by a small amount of seconds (eg, 2 microseconds). As described, the user station 302 may advance or delay timing using techniques or other suitable means conventionally developed in the GSM system already developed and described above.

In one embodiment, the delay time ΔT is preferably set equal to the receive / transmit switching time of the user station 302. Therefore, the delay associated with the user station 302 switching from the receive mode to the transmit mode is not included in the RTT measurement. The delay time ΔT should also be chosen short enough so that there is no duplication between the reply message 562 of the specific user station 302 and the transmission between the user station-base station in another receiving time slot 511.

If two user stations 302 attempt to set up a communication transmission in the same receive time slot 511 using a short reply message 562, then the reply message 562 may indicate that each user station 302 has a base station 304. It may or may not overlap, depending on how far away it is). In some situations, simultaneous reply messages 562 may be jammed. If base station 304 receives two acknowledgment messages 562 in the same receiving time slot 511, the base station may select a user station 302 with a stronger signal for communication.

Alternatively, base station 304 may initiate a backoff procedure or otherwise resolve the contradiction when appropriate for a particular application. For example, the base station 304 may back off each user station 302 for various periods based on internal programming variables unique to each user station 302 (eg, a unique user identification number, etc.). Generates a backoff command. Alternatively, if base station 304 can identify between two acknowledgment messages 562, base station 304 relocates one or both user stations 302 to different slot pairs 510, 511. Command to

The system of FIGS. 5A-5B combines a TDD / TDM / TDMA message structure that adjusts reverse link transmission timing such that user-to-base station messages sent from user station 302 arrive at base station 304 without being sequentially duplicated. One feature is shown. The base station 304 using the TDM technique transmits a single long burst data including a plurality of base station-user station messages in a time frame 501 for each transmission time slot 510. Transmit during section 502. After the transmitter 502, the base station 304 is switched to the reception mode. Each user station 302 extracts the intended specific data from the long base station burst. Reverse link transmission is not initiated until all user stations 302 have a chance to receive their forward link data. Thereafter, the user station 302 responds one by one in the allocated reception time slot 511 at the same frequency used by the base station 304 with only the minimum guard band between each reception. In order to prevent interference between user station transmissions, base station 304 instructs user station 302 to advance or delay their transmission timing as needed.

FIG. 6 is a graph of total round trip time protection time (ie, sum of integrated protection 503 and brief protection band 512 and transmit / receive switching delay) as a percentage of frame time of the system of FIGS. 5A-5B. 4 microseconds is added to account for the transmit / receive switching delay, and assume that the reverse link TDMA time slots are separated by 2 microseconds to allow timing errors. A time frame 501 with an interval of 4 microseconds is selected in the example of FIG. The graph of FIG. 6 shows that relatively suitable overall requirements are possible even when the cell diameter reaches 25 miles. The graph of FIG. 6 also shows that as the number of time slots increases, more total time is allocated for user station timing errors per time frame 501, but the total remains never less than 10% for a cell of 25 miles in diameter. can not do.

7 is a diagram of a TDD / TDM / TDMA timing structure with alternative initial timing protocols for reducing total round trip protection time. As with FIGS. 5A-5B, the features of the TDM of FIG. 7 relate to base station transmission and the TDMA features relate to user station transmission.

The embodiment of FIG. 7 uses an integrated protection unit 503 (already shown in FIG. 5A) for initial setup of communication and RTT measurements. The scheme of FIG. 7 contrasts with the scheme described with respect to FIG. 5B, where each receive time slot 511 is preferably a maximum round trip protection time (+ acknowledgment message length) due to initial round trip timing uncertainty as mentioned. And the same section. In the system of FIG. 5B in which the time frame 501 includes many receive time slots 511 in a relatively short period, the initial round trip timing uncertainty may cover some receive time slots 511. In this case, an attempt to transmit an acknowledgment message 562 during the initial link-up by one user station 302 interferes with the data link transmission from another user station 302 so that the base station 304 during the receive time slot 511. Will interfere with or duplicate the message received.

To avoid such a situation, each receive time slot of the system of FIG. 5B should be at least the sum of the maximum round trip protection time and the interval of the response message 562. Therefore, the maximum round trip time sets the maximum upper limit on the number of time slots in the system of FIG. 5B.

The system of FIG. 7 solves this problem by using an indication of the time frame 501 in the initial setup of the communication. In the system of FIG. 7, the initial communication link-up (including RTT transmission) is to prevent the RTT reply message from providing the ability to handle more time slots (especially in a particular cell) that are more likely to interfere or interfere. During the downtime of the integrated protection 503 between the distal end of the transmitter 502 of the time frame 501 and if necessary comprising a first receiving time slot 511 of the receiver 504 of the time frame 501. Is performed. An integrated protection unit 503 is used in the system of FIG. 7 to assist in establishing an initial barrel link between the base station 304 and the new user station 302.

In the system of FIG. 7, the transmission time slot 510 may include a header similar to the header 550 shown in FIG. 5B. The header may indicate whether a particular time slot pair 510, 511 is free. If the time slot pairs 510 and 511 are free, then the user station 302 wishing to establish a communication responds with a message indicating the desired time slot of the communication. If the header is not used, the user station 302 responds to the normal request for access and the base station 304 uses the specific time slot pair 510, 511 for communication to the user station 302 in the next time frame 501. You can also command). The normal access request by user station 302 may include a user station identifier that causes base station 304 to specifically address the user station 302 requesting access.

The header 550 in the system of FIG. 7 may include a command indicating a delay time ΔT after the user station 302 requesting communication setup has responded. Alternatively, such delay time ΔT may be programmed as a system variable such that the user station 302 delays the response until the delay time ΔT elapses. After detecting the distal end of the base station transmission 502 and waiting for the delay time ΔT to elapse, the user station 302 sends an RTT reply message 701 or 702.

If the user station 302 is very close to the base station 304, the RTT reply message 701 will appear at the base station 304 immediately after the end of the base station transmission 502 and within the integrated protection unit 503.

When the user station 302 is in close proximity to the cell, the RTT reply message 702 is directed to the terminal of the integrated protection unit 503 or to the first of the receiving unit 504 of the time frame 501, depending on the particular system limitations and systems. Appears at base station 304 within receive time slot 511. The first receive time slot 511 usable in the established data link communication is the designated first receive time slot 511 after the maximum round trip propagation delay (including message length) of the response message from the user station 302 around the maximum cell. to be. Some guard time allowance may be added to ensure that an acknowledgment message from a farther deployed user station 302 does not interfere with the reverse data link transmission from the user station 302 in the established communication.

In embodiments where header 550 includes information about the availability of time slot pair 510, RTT reply message 701 or 702 may allow user station 302 to use any available time slot for communication. It may also include a time slot identifier indicating whether it is desired. User station 302 also determines time slot availability by monitoring user transmission 504 for base station 502 and / or for a period of time, so that user station 302 may use any available time slot pair 510, 511. May send an RTT reply message 701 or 702 that includes a time slot identifier indicating whether it is desired to use for communication. During the first transmission time slot 510 of the transmitter 502, the base station 304 authorizes the user station 302 to use the time slot pairs 510 and 511 requested for communication and for different time slot pairs for communication. Commands may be issued to instruct user station 302 to use 510 and 511 or to notify user station 302 that base station 304 is in use.

If the header is not used or the user station 302 does not have specific information about the availability of the time slot pairs 510 and 511, the user station 302 sends an RTT reply message 701 or 702 for access. Send as normal request. In response, during the first transmission time slot 510 of the transmitter 502, the base station 304 instructs the user station to use a particular time slot pair 510, 511 for communication or indicates that the base station 304 is busy. A command may be issued to notify the user station 302 that it is. A typical access request by user station 302 may include a user station identifier that causes base station 304 to specifically address the user station 302 requesting access.

In one embodiment of the system of FIG. 7, if all other time slot pairs 510, 511 are not in use when the first receive time slot 511 can be used for data link communication, a first receive of the receiver 504. Time slot 511 is only used for RTT reply message 701 or 702 to establish communication. In the latter case, if another time slot pair 510, 511 becomes available as a result of termination of communication with a different user station 302, the user station 302 occupying the first receiving time slot 511 is available. The first receive time slot 511 may be initiated for access by the new user station 302 searching to establish communication with the same base station 304 as it may be sent to the receive time slot 511.

In the above-described embodiment where the first receiving time slot 511 of the unified protection unit 503 and the receiving unit 504 is used to receive the RTT reply message 701 or 702, the unified protection time 503 and the first receiving The combined length of the time slots 511 should be at least the sum of the maximum round trip propagation time and the duration of the RTT reply message 701 or 702.

In a variant of the embodiment of FIG. 7, only the integrated protection unit 503 is used to receive the RTT reply message 701 on the initial communication link-up. In the present embodiment, the first receiving time slot 511 is not used for that purpose. In this variant, the length of the integrated protection unit 503 should be at least the sum of the maximum round trip propagation time and the interval of the RTT reply message 701.

After receiving the RTT reply message 701 or 702 at the base station 304, the response scheme of the base station 304 is in accordance with a particular system protocol. As mentioned, the base station 304 may transmit using the header 550 but may not be necessary, and the user station 302 may respond to the RTT reply message 701 or 702 with or without a specific time slot request. And the first receiving time slot 511 may or may not be used to receive the RTT reply message 701 or 702. Therefore, the response scheme of the base station 304 depends on the specific structure of the system, and the specific embodiments described herein are not meant to limit the possible base station / user station initial communication processing that falls within the scope of the present invention.

If the first receiving time slot 511 is in use along the unified protection time 503 to receive the RTT reply messages 701, 702, then the base station 304 may determine that the transmitter 502 immediately after the time frame 501. It may respond to the RTT reply message 701 or 702 with an initial communication response message in the first transmission time slot 510. Base station 304 may initially use a particular transmission time slot 510 (eg, a first transmission time slot 510) for assistance.

If the RTT reply message 701 or 702 identifies a particular time slot pair 510, 511 that the user station 302 wants to use for communication, the base station 304 transmits the transmission time slot specified in the next time frame 510. One or both of header 550 and data message portion 551 of 510 may respond to user station 302. When two user stations 302 simultaneously transmit an RTT reply message 701 or 702 requesting to initiate communication with a pair of time slots 510, 511, the base station 304 may send two user stations 302. Send a response in the header 550 of the designated transmission time slot 510, which selects one and instructs another user station 302 to use a different time slot pair 510, 511 or to back off for a period of time. At the same time, the frame 510 may transmit data messages in the data message portion 551 of the designated transmission time slot 510 intended by the selected user station 302.

If two user stations 302 attempt to access base station 304 at the same time (ie, in the same frame 501), base station 304 may select user station 302 with a stronger signal.

Alternatively, base station 304 may initiate a backoff procedure or otherwise resolve the collision when appropriate for a particular application. For example, base station 304 may allow each user station 302 to back off for a variable period based on internal programming variables (eg, unique user identification numbers) unique to each user station 302. A backoff command may be generated.

As another alternative, the base station 304 may instruct the user station to relocate to different time slot pairs 510, 511. If each of the acknowledgment messages 701, 702 contains a different time slot identifier (assuming that user station 302 has information on which time slot is open from base station header 55), then base station 304 ( For example, two user stations 302 provided with reply messages 701, 702 that are not modulated by mutual interference, which may occur if different user stations 302 are spaced the same distance from the base station 504. Communication can be started at the same time.

As in the embodiment of FIG. 5B, in the embodiment of FIG. 7, the RTT reply message 701 or 702 determines the timing appropriate for the user station 302 by measuring the propagation delay upon receipt of the reply message 701 or 702. May be used by the base station 304 for this purpose. The user station 302 searches to set the communication delay for the delay time DELTA T after receiving the base station transmission 502 and before transmitting the acknowledgment message 701 or 702. The base station 304 at the user station 302 either measures the round trip propagation delay from the end of the base transmission 502 to the actual reception time of the response message 701 or 702 or considers the delay time ΔT. The propagation delay to the base station 304 is determined.

Once the propagation delay time is determined, the base station 304 instructs the user station 302 to advance or delay its timing by a predetermined amount in relation to the appropriate time slot pairs 510 and 511 to be used for communication. . For example, base station 304 may instruct user station 302 to precede its timing by an amount of time, such as round trip propagation time, such that user station 302 necessarily transmits at the extreme of shortened guard 512. . The user station 302 may advance or delay its timing, for example, by any technique or technique conventionally developed and used in the GSM system described above.

In FIG. 7 the time delay ΔT is preferably set equal to the greater of the transmit / receive switching time of the base station 304 and the receive / transmit switching time of the user station 302. The reason is that even if the responding user station 302 is placed very close to the base station 304, it ensures that the delay of the user station 302 is not included in the RTT measurement when switching from the receive mode to the transmit mode, To allow 302 an appropriate processing time. Once the user station 302 wishing to establish communication has detected the termination of the base transmission 502, the user station 302 may have responded that the response message 562 is with forward link reception by another user station 302. As it is physically impossible to undertake an outgoing forward link message that causes interference, the response message 562 may begin immediately after the delay time DELTA T without fear of interference.

8A is a hardware block diagram of a base station 304 in accordance with an embodiment of the present invention. Base station 304 of FIG. 8A includes data interface 805, timing command unit 806, transmitter 807, antenna 808, receiver 809, mode control 810, TDD state control 811, and A propagation delay calculator 812 is provided.

Timing control for the system of FIG. 8A is performed by TDD state control 811. TDD state control 811 includes appropriate means such as a counter and clock circuit to maintain synchronous operation of the TDD system. The TDD state control 811 thereby comprises a time frame 501 and its component parts, each of which includes a transmit time slot 510, a receive time slot 511, a shortened guard 512, and a collective protector 503, respectively. Accurately time your cycle.

TDD state control 811 may often be synchronized with a system clock that may be located in a base station controller, cluster controller, or associated network, to enable global synchronization among base stations in a band or cluster.

Mode control 810 selects between the transmit mode and receive mode of operation. Mode control 810 reads the information from TDD state control 811 to determine the appropriate mode. As indicated by the status bits in the TDD state control 811, for example, at the end of the transmitter 502, the mode control 810 can switch modes from transmit mode to receive mode. As indicated by the status bits in the TDD state control 811, for example, at the end of the receiver 504, the mode control 810 can switch modes from the receive mode to the transmit mode.

During the transmission mode, data to be transmitted is supplied from the data bus 813 to the data interface 805. The data interface 805 supplies the data to be transmitted to the timing command unit 806. As described in detail herein, the timing command unit 806 may format the data to be transmitted to include the timing adjustment command 815 if necessary. The data output by the timing command unit 806 may be in the same format as the transmitter 502 shown in FIG. 5A, which causes the data destined for each user station 302 to be properly separated.

The output of the timing command unit 806 is supplied to the transmitter 807, which modulates the data for communication and transmits data destined for each user station 302 in the appropriate transmission time slot 510. The transmitter 807 obtains the necessary timing information directly from the mode control 810 or the TDD state control 811. The transmitter 807 may be equipped with a spread spectrum modulator as known in the art. Data is transmitted by the transmitter 807 from the antenna 808.

User station 302 receives the transmitted data, normalizes the responding user-to-base station message, and forwards the user-to-base station message in reverse order. The structure of the user station 302 in which transmission from the base station 304 and reception of normalization of the message in response is performed is shown in FIG. 9 and described below. The message from user station 302 appears at base station 304 in receive time slot 511.

After switching from transmit mode to receive mode, antenna 808 is used to receive data from user station 302. Although one antenna 808 is shown in Figure 8A, other antennas may be used for the transmit and receive functions, and multiple antennas may be used for the purpose of achieving the benefit of antenna diversity. Antenna 808 is coupled to receiver 809. Receiver 809 may have a demodulator or spread spectrum correlator or both. The demodulated data is supplied to the data interface 805 and thus the data bus 813. The demodulated data is also supplied to a propagation delay calculator 812 that calculates a propagation delay time for the RTT transaction.

In operation, the timing command unit 806 inserts a timing adjustment instruction, such as a time period T (which may or may not include the delay period ΔT used in the initial round trip transaction) into the transmission time slot 510, Instruct user station 302 to delay sending its response by an amount of time equal to the time period ΔT. The timing adjustment command may be placed at the designated location of the base station-to-user message sent during the appropriate transmission time slot 510. For example, the timing adjustment command may be placed in the header 550 or the data message unit 551 of the transmission time slot 510. At initial communication link-up, the timing adjustment command is preferably set to the receive / transmit switching delay time of the user station 302, and then adjusted based on the calculated delay time.

The user station 302 receiving the timing adjustment command thereby delays delivering its response by the amount of time specified. The response message sent by the user station 302 is received by the receiver 809 and supplied to the propagation delay calculator 812. Propagation delay calculator 812 obtains accurate timing information from TDD state control 811 and propagation delay calculator 812 accurately determines the air propagation delay of the response message sent from user station 302. In particular, the propagation delay is the amount of time equal to the actual reception time of the response message from the user station 302 and the time T past the start of the appropriate reception timing slot 511 (if such a delay is programmed in each user response). If so, it can be calculated as the time difference between the delay periods ΔT).

In the preferred embodiment, the propagation delay calculator 812 then calculates a new timing adjustment instruction 815 for the particular user station 302. The new timing adjustment command 815 preferably responds from any other user station 302, with the response message from the user station 302 starting at the end of the reduced guard 512 in the next time frame 501. It is chosen not to duplicate the message. For example, the new timing adjustment command 815 may be equal to the calculated round trip time for the particular user station 302.

The timing adjustment command 815 may be updated as often as necessary to maintain sufficient quality of communication between the base station 304 and all user stations 302. The propagation delay calculator 812 thus preferably stores the timing adjustment command 815 calculated for each independent user station 302. As the user station 302 moves closer to the base station 304, the timing adjustment command 815 increases, while the timing adjustment command 815 as the user station 302 moves away from the base station 304. Is reduced. As such, in a dynamic manner, the timing of the user station 302 is preceded or delayed, and ongoing communications between the base station 304 and the user station 302 may be responsive to user-to-received received from the user station 302. It will not be interrupted by duplicating base station messages.

8B is a hardware block diagram of an alternative embodiment of base station 304. FIG. 8B is similar to that of FIG. 8A except that a start counter command and a stop counter command are used as follows. At the start of the base transmission from the transmitter 807, a start counter command 830 is passed from the transmitter 807 to the TDD state control 811 for the target user station 302. When the receiver 809 receives a response from the target user station 302, the user station sends a stop counter command 831 to the TDD state control 811 for the target user station 302. The value stored in the counter for a particular user station 302 represents the round trip propagation delay time. Individual counters may be used for each user station 302 that the base station 304 contacts.

9 is a hardware block diagram of a user station 302 in accordance with an embodiment of the present invention. The user station 302 of FIG. 9 includes a data interface 905, a timing command interpreter 906, a transmitter 907, an antenna 908, a receiver 909, a mode control 910, and a TDD state control 911. It is provided.

Timing control for the system of FIG. 9 is performed by TDD state control 911. The TDD state control 911 has appropriate means such as a counter and clock circuit to maintain synchronous operation of the user station 302 in the TDD system. The TDD state control 911 thereby causes the duration of its components to include a time frame and each of a transmit time slot 510, a receive time slot 511, a short guard 512, and a collective protector 503. Accurately time the period.

The mode control 910 selects between a transmission mode and a reception mode of operation. Mode control 910 reads information from TDD state control 911 to determine the appropriate mode. For example, in response to a status bit in TDD state control 911, mode control 910 may switch to the receive mode during the appropriate transmission time slot 510 of time frame 501. In response to the status bit in the TDD state control 911, the mode control 910 may switch the mode to the transmit mode during the appropriate receive time slot 511. At other times, the mode control 910 may remain in receive mode to maintain a rest mode, to monitor activity of another nearby base station 304 or to monitor transmissions from the base station 304 for other purposes. Can be.

During the transmission mode, data to be transmitted is supplied from the data bus 913 to the data interface. The data interface 905 provides the data to be transmitted to the transmitter 907 which modulates the data for communication and transmits the data in the appropriate time slot 511. The transmitter 907 obtains the necessary timing information directly from the mode control 910 or the TDD state control 911. The transmitter 907 may be equipped with a spread spectrum modulator such as is known in the art but is not required. Data is transmitted by the transmitter 907 from the antenna 908.

Base station 304 receives the transmitted data, normalizes the responding base station-to-user message as needed, and forwards the base station-to-user message to the appropriate transmission time slot 510.

In the receive mode, antenna 908 is used to receive data from base station 304. Although only one antenna 908 is shown in the FIG. 9 embodiment, other antennas may be used for the transmit and receive functions or multiple antennas may be used to obtain antenna diversity. Antenna 908 is coupled to receiver 909. Receiver 909 may have a demodulator or spread spectrum correlator or both. The demodulated data is supplied to the data interface 905 and thus the data bus 913. The demodulated data is also supplied to a timing command interpreter 906 for applying the timing adjustment command received from the base station 304.

In operation, timing command interpreter 906 parses the data received from base station 304 to determine a timing adjustment command. Assuming that the timing adjustment command includes a time T equal to the calculated round trip propagation (RTT) time, the timing command interpreter 906 (such as near the beginning of the next time frame 501) to achieve an overall reordering of that timing. The clock and / or timer in the TDD state control 911 can be reset at a suitable moment. If the timing adjustment command is an instruction to advance the timing by the amount of time T, then the timing command interpreter 906 may reset the TDD state control 911 at a period of time T immediately after the elapse of the current time frame 501. .

As noted, the timing adjustment command may be represented by a number of bits or chips that the user station 302 must precede or delay its timing. The timing adjustment command can also be expressed in fractional timing units (ie, milliseconds).

Optionally, timing command interpreter 906 can maintain internal timing adjustment variables, utilizing a delta modulation technique. The internal timing adjustment variable is updated each time a timing adjustment command is received from the base station 304. If the timing adjustment command is an instruction that precedes the timing, then the timing adjustment variable is reduced by the amount T. If the timing adjustment command is an instruction to delay timing, then the timing adjustment variable is increased by the amount T. The timing adjustment variable may be added to the output of the TDD state control 511 to synchronize with base station timing. Optionally, timing adjustment variables may be provided directly to the transmitter 907 and the receiver 909 that change the timing of their operation.

The timing command interpreter 906 may include a primary tracking circuit that interprets the requested change in transmission timing from time period to time period and adjusts the timing of user station 302 transmission based on the same.

FIG. 5C is a timing diagram depicted from base station time, showing the deviation of the TDD / TDM / TDMA system of FIG. 5A using an interleaved symbol transmission format. FIG. In FIG. 5C, the time frame 570 is divided into a transmitter 571, a collective guard time 576, and a receiver 572 similar to FIG. 5A or 7. During transmitter 571, base station 304 transmits to multiple user stations 302 during multiple transmission time slots 574. In each transmission time slot 574, instead of sending a message destined for one user station 302, the base station 304 may sub-message 589 (or receive time for each of the user stations 302). If the slot is not occupied, an interleaved message 578 is sent, including sub-message 589 for general polling or other functions. The user station 302 thus receives a portion of its overall incident message from each of the transmit time slots 574 and carefully listens to the entire transmitter 571 for the full message during the time frame 570. listen over)

More specifically, as shown in FIG. 5C, each transmit time slot 574 may include a number of sub-messages 589, preferably each receive time slot 575 (and thus each potential user). One sub-message 589 for one sub-message 589 for station 302. For example, if there are sixteen transmit time slots 574 and sixteen receive time slots 575, each transmit time slot 574 is assigned to 589-1, 589-2,... 16 sub-messages 589, referred to in the order of 589-16. Each sub-message 589 preferably has the same number of symbols, ie 40 symbols. The first sub-message 589-1 is for the first user station 302, the second sub-message 589-2 is for the second user station 302, and so on. The last sub-message 589. -16). The user station 302 is responsible for the incoming messages from the appropriate sub-message 589 in the first transmission time slot 574, up to the last taming slot 574 where the user station 302 receives the last portion of the message. Some, the next portion of the incoming message, etc., from the appropriate sub-message 589 of the second transmission time slot.

In each transmission time slot 574, it is the preamble 577 that precedes the interleaved message 578. The preamble 577 assists in synchronizing the user station 302 and may have a spread spectrum code. Preamble 577 appears in each transmission time slot 574 and spreads throughout transmission 574 to cause user station 302 to rake receiver (ie, synchronize) and / or select diversity. Enable channel sounding operations useful for setting up the system. Since the user station 302 obtains its information across the entire transmitter 571, the communication path is less susceptible to sudden fading or interference that only affects the relatively brief period of the transmitter 571. Thus, if interference or fading corrupts the information in a particular time slot 574 (ie, the second transmission time slot 574), the user station 302 is still unaffected by such interference or fading. Will have five sub-messages 589.

By using forward error correction techniques, user station 302 may correct one or more sub-messages 589 received in error. Preferred forward error correction techniques generally use Reed-Solomon codes, which can be generated by algorithms known in the art. The number of errored sub-messages 589 that can be corrected is represented by the formula INT [(R-K0 / 2] where R = number of symbols passed to user station 302 during the burst period, K = traffic information. (I.e., the number of symbols used for non-error correction, and INT represents a function of rounding down the nearest information), thus R (N, K) specified in Reed-Solomon code. In the case of R = (40, 31), the faulty sub-message 589 up to INT [(40-31) / 2] = 4 can be corrected.

Although a particular symbolic interleaving scheme is shown in Figure 5C, other symbolic interleaving techniques, such as diagonal interleaving, may also be used.

The user station 302 responds via the reverse link in the same way as described in connection with FIG. 5A or 7. Thus, the user station 302 responds with user transmissions in the designated receive time slot 575 of the receiver 572. Receive time slot 575 has a preamble 575 and a user message 580. Receive time slots 575 are separated by shortened guard time 573, and the range can be used to instruct user station 302 to advance or delay its timing as previously described.

5D is a chart comparison performance of a particular TDD / TDM / TDMA system according to FIG. 5A without forward error correction, and a particular system according to FIG. 5C without forward error correction. 5D shows the frame erotic probability for signal-to-noise ratio (Eb / No) (dB). FIG. 5D shows separate views of 1, 2, and 4 different Lake Diversity channels L (ie, multiple paths that can be resolved). Solid lines in FIG. 5D represent the performance of the FIG. 5A system without forward error correction, while dashed lines represent the performance of the FIG. 5C system with Reed-Solomon forward error correction. 5D thus shows a substantial reduction in frame error probability through the FIG. 5A system using interleaved symbol transmission and forward error correction.

Another embodiment of a timing component associated with a time frame structure for performing communication between a base station and multiple user stations is shown in FIGS. 10A-10E. 10A is a timing diagram of a sub-element with a predetermined format for use in a time division duplex system. The three timing sub-elements shown in FIG. 10A can be used to construct a time division duplex frame structure such as the frame structure shown in FIGS. 10B-10E. Although the system configured according to FIGS. 10A-10E preferably uses spread spectrum for communication, no spread spectrum is necessary. However, the following description assumes the use of spread spectrum techniques. For this example, a chipping rate of 5 MHz is desirable.

10A shows a base timing sub-element 1001, a user datalink timing sub-element 1011, and a range timing sub-element 1021. For each of these sub-elements 1001, 1011 and 1021, as described in detail below, for the range timing sub-element 1021, from the time of the base station 304 where the initial range of the user station 302 is zero. The timing is shown.

More specifically, the ranging process is performed between the base station 304 and the user station M3, so that the user station M3 selects the preamble during the ranging preamble interval 1022 of the time slot TS4 '. The ranging message is transmitted during the user ranging message interval 1023 of TS4 '. The user station M3 delays the transmission of the preamble and ranging message for the amount of time DELTA T. The delay time ΔT may be communicated by the base station 304 as part of a normal polling message, or may be a preset system parameter. The base station 304 takes into account the delay from the user station M3 at the end point of the base station message interval 1003 in the fourth time slot TS4 '(i.e., the first possible reception of the preamble and ranging message) taking into account the delay time ΔT. The transmission delay from the user station M3 to the base station 304 is determined by measuring the round trip transmission delay up to the actual reception time of the preamble and ranging message.

The ranging guard band 1024 in the time slot TS4 'is preferably of sufficient length to allow ranging processing between the base station 304 and the user station M3. Thus, the length of the ranging guard band 1024 may be determined in part by the radius of the cell in which the base station 304 is located or in part by the maximum cell radius of the cellular system.

In response to receiving the ranging message from the user station M3 and determining the distance of the user station 302 and / or the transmission delay time therefor, the base station 304 in response to the user station M3 in the next time frame 1050. ), A timing adjustment command can be issued to instruct the user station M3 to advance or delay the timing by a specified amount. During the time frame 1050 immediately after communication with the user station M3 is made, the timing adjustment command may be set equal to the round trip transmission time determined by the base station 304 in the lasing process. Preferably, the timing adjustment command is received by the base station 304 immediately after the end of the transmit / receive switch interval 1004 from the user station M3 in the subsequent time frame 1050 to the base station 304 so that the base station ( 304 is selected not to interfere with the base station to user station messages sent in the base station message interval 1003, while providing an opportunity to switch from the transmit mode to the receive mode.

The base station 304 may periodically instruct the user station 302 to adjust its timing, for example, by issuing a continuous timing adjustment command frequently, e.g., every time frame. The base station 304 may monitor the distance of the user station 302 by measuring the reception time of the user station to base station message. Preferably, however, the base station 304 monitors the range of the user station 302 using the reception time of the control pulse preamble due to the known preamble timing and message structure and during the base station to user station message interval according to the timing adjustment command. Answer.

In addition to being used for ranging, the ranging message may include other information to assist in handshaking between the base station 304 and the user station M3. For example, the ranging message may include, as data, the user identifier of the user station M3 with which to communicate. The ranging message may also indicate the preferred spread spectrum code to be used by the base station 304 and the particular user station M3 in subsequent communications.

10E shows a subsequent time frame 1050 after the ranging process is completed at the third user station M3. In Fig. 10E, the processing between the user stations M1 and MN and the base station 304 occurring in the first time slot TS1 'is the same as in 10D. The processing between the user stations M1 and M2 and the base station 304 occurring in the second time slot TS2 is also the same as in FIG. 10D. However, during the second time slot TS2 ', instead of the control pulse preamble transmitted in the preamble interval 1016, the third user station M3 does not have a preamble interval 1016 of the second time slot TS2'. The control pulse preamble can be transmitted. In addition, the user station M3 receives the ranging message transmitted in the preceding time frame 1050 before the base station 304 transmits the control pulse preamble during the preamble interval 1016 of each preceding time slot TS2 '. You can also wait for confirmation.

Base station 304 may use the control pulse preamble for various purposes, including power control and other purposes, as described above. In the third time slot TS3 ′ of FIG. 10E, the base station 304 may respond by transmitting an acknowledgment signal to the user station M3 during the base station message interval. The acknowledgment signal may be transmitted using a spread spectrum code determined by the user identifier transmitted by the user station M3 as part of the ranging message. As part of the acknowledgment signal or else, the base station 304 preferably sends a timing adjustment command to instruct the user station M3 to advance or delay its timing by a specified amount.

Subsequent to time frame 1050, use with base station 304 in time slots TS3 ', TS4' (in each time frame 1050 in addition to receiving control pulse preamble in second time slot TS2 '). Communication between the stations M3 may be performed in an interleaved manner. In each preamble interval 1016 of the second time slot TS2 ', the user station M3 is responsible for the base station 304 taking a certain operation, e.g., performing power control, or synchronizing with the user station M3, Or transmit a control pulse preamble that allows measuring the distance of user station M3. The base station 304 then transmits a communication signal to the user station M3 during the first portion of the third time slot TS3 'and the user station M3 transmits the base station during the second half of the next time slot TS4'. Respond with a communication signal directed to 304. In each communication from the base station 304, the base station 304 may update the timing adjustment command for the user station M3.

When the user station 302 terminates communication in time slot 1051 or is connected to a new base station 304, base station 304 is free of time slot 1051 for communication during newly initiated time slot 1051. You can start sending a general purpose polling message that indicates it is good. Accordingly, new user stations 302 can communicate with the same base station 304.

In another embodiment of the present invention described with reference to Figures 11A-D, instead of a single frequency band, bands of two frequencies are used for communication.

11A is a diagram of timing subelements with a predetermined format used in an FDD / TDMA system. The three timing subelements shown in FIG. 11A can be used to construct an FDD / TDMA frame structure such as the frame structure shown in FIGS. 11B-D. It is preferred that systems configured according to FIGS. 11A-D use spread spectrum for communication, but no spread spectrum is required. However, the description below uses spread spectrum techniques. In the present embodiment, unless otherwise specified, the chipping rate of 2.8 MHz is preferred although the chipping rate selected is application dependent.

11A shows a base station timing subelement 1101, a user station data link timing subelement 1110, and a range timing subelement 1121. As shown in FIG. For each of these sub-elements 1101, 1110, 1121, as described in more detail below, timing is shown from a perspective view of the base station with the range of the user station 302 being zero.

Base station timing subelement 1101 is referred to as base station preamble interval 1102, base station message interval 1103, three preamble burst intervals 1104, 1105, and 1106 (these are collectively referred to as 123 preamble burst intervals 1109). ), The base station charging code interval 1107, and the transmit / receive switch interval 1108. The base station preamble interval 1102 may have a length of 56 chips. The base station message interval 1103 may have a length of 205 bits, or 1312 chips using 32 binary coding, as described above with reference to FIGS. 10A-E. Base station message interval 1103 includes a total of up to 41 5-bit data sequences for a total of 205 bits, so that transmissions within base station message interval 1103 are each selected from 32 spread spectrum code sets, for a total of 1312 chips. A series of up to 41 spread spectrum codes can be included.

Although the preferred system of the present invention of Figures 11A-E has been described using 32 binary spread spectrum coding techniques, other spread spectrum techniques including other M binary coding techniques (quad, hexadecimal, etc.) may also be used, depending on the particular system requirements. Can be.

The three preamble burst intervals 1104, 1105 and 1106 are each preferably 56 chips long, so the 123 preamble burst intervals 1109 are preferably 168 chips long. The transmit / receive switch interval 1108 is preferably selected with a length of time sufficient to enable switching of the base station 304 from transmit mode to receive mode, for example 32 chips or a length of 11.43 ms. The transmit / receive switch interval 1108 and the base station charging code interval 1107 collectively comprise 189 chips in length in the preferred embodiment.

Thus, the total length of the base station timing subelements 1101 is 1750 chips (2.8 MHz) consistent with the lengths of the user station data link timing subelements 1110 and the range timing subelements 1121 as described below. Is assumed to be the chipping rate. In the embodiment of Figs. 11A-D, maintaining synchronization in the dual frequency band system shown in Figs. 11A-D, where the base station 304 communicates in one frequency band and the user station 302 communicates in another frequency band. For this purpose, it is preferable to have a base station timing subelement 1101 having the same length as the user station timing subelements 1110 and 1121.

The user station data link timing subelements 1110 and the range timing subelements 1121 each generally provide for transmission by two or more user stations 302. As described below, the timing subelements 1110 and 1121 are used by the first user station 302 to transmit a data message or ranging message to a first portion of the timing subelement 1110 or 1121, And a transmission of the control pulse preamble at the second half of the timing subelements 1110 or 11210 by the second user station 302. As described below, the control pulse preamble is generally used by the base station 304 in a second manner. Perform certain functions (eg, power control) with respect to user station 302.

The user station data link timing subelement 1110 includes a data link preamble interval 1112, a user station message interval 1113, a guard band 1114, a transmit / receive switch interval 1115, a second preamble interval 1116, and an antenna. Adjustment interval 1117, second guard band 1118, and second transmit / receive switch interval 1119. The preamble intervals 1112 and 1116 may each be 56 chips long. The user station message interval 1113 may be 205 bits or 1312 chips long using the 32-bit spread spectrum coding technique described above. The length of guard bands 1114 and 1118 may be a period sufficient to allow appropriate switching between transmit / receive modes or between receive / transmit modes, respectively, as the case may be. Antenna coordination interval 1117 selects a particular antenna beam, permits minor coordination with respect to the angle of the directional antenna at base station 302, or selection of one or more antennas when base station 302 is equipped with one or more antennas. There may be a sufficient period of time to allow the transmission of data symbols to permit.

The range timing subelement 1121 includes the ranging preamble interval 1122, the user station ranging message interval 1123, the ranging guard band 1124, the transmit / receive switch interval 1125, the second preamble interval 1126, An antenna adjustment interval 1127, a second guard band 1128, and a second transmit / receive switch interval 1129. The preamble intervals 1122 and 1126 may each be 56 chips long. The user station ranging message interval 1123 may be 150 bits or 960 chips long using the 32-bit spread spectrum coding technique described above. The length of the ranging guardband 1124 is, for example, variable depending on the cell radius, but should be sufficient to allow reception of the ranging message without interference. The other guard band 1128 should also be long enough to allow the receipt of appropriate information without interference. The transmit / receive switch intervals 1125 and 1129 may optionally be periods sufficient to allow proper switching between transmit / receive modes or between receive / transmit modes, respectively. Antenna coordination interval 1127 selects a particular antenna beam, permits minor coordination with respect to the angle of the directional antenna at base station 302, or selection of one or more antennas when base station 302 is equipped with one or more antennas. There may be a sufficient period of time to allow the transmission of data symbols to permit.

The total length of each of the user station data link timing subelements 1110 and range timing subelements 1121 may be the same length as the 1750 chip or base station timing subelements 1101. These specific examples assume a chipping rate of 2.8 MHz.

FIG. 11B is a timing diagram for a constant or zero offset FDD / TDMA frame structure using the timing subelements shown in FIG. 11A. The frame structure of FIGS. 11B-E is shown from a perspective view of base station 304.

11B is a frame structure in a system using two frequency bands for communication in addition to the features of time division multiple access. The first frequency band 1170, referred to as the base station frequency band, is primarily used for communication from the base station 304 to the user stations 302. The second frequency band 1171, referred to as the user station frequency band, is mainly used for communication from the user stations 302 to the base station 304. The two frequency bands 1170 and 1171 are preferably separated by 80 MHz. The frequency separation of 80 MHz helps to minimize co-channel interference and allows a simpler structure of the filter in the receiver to remove potential interference signals from the reverse path communication signal.

In the frame structure of FIG. 11B, time frame 1140 includes a plurality of time slots 1141. For convenience, time slots are assigned sequentially, such as TS1, TS2, TS3, and the like. Each time slot 1141 includes a base station timing subelement 1101 on a base station frequency band 1170 and a user station data link timing subelement or range timing subelement 1121 on a user station frequency band 1171. Include. Time slots 1141 are shown from a perspective view of base station 304, such that base station timing subelements 1101 and user station timing subelements 1110 and 1121 are shown in line in FIG. 11B. Although the frame structure of FIG. 11B supports range timing subelements 1121 on user station frequency band 1171, communication from user station 302 to base station 304 in FIG. 11B is typically a user data link subrelease. It should be considered that this is done using the comments 1110.

In operation, the base station 304 continuously transmits to the user station 302 to which the base station 304 establishes communication as part of the base station timing subelement 1101 of each time slot 1141. More specifically, base station 304 transmits a preamble during preamble interval 1102 and a base station to user message during base station message interval 1103. After base station message interval 1103, base station 304 sends three short preamble bursts to another user station 302 within a 123 preamble burst interval 1109. In the example system of FIG. 11B, three preamble bursts within the 123 preamble burst interval 1109 are sent from the base station 304 to the user station 302 receiving the main data message after two time slots 1141.

Three short preamble bursts transmitted in the 123 preamble burst interval 1109 may be used for forward link diversity detection and forward link power control. Each of the three preamble bursts may be transmitted over another antenna to provide the receiving user station 302 with the opportunity to make diversity selections for the arriving forward link data message in the subsequent time slot 1141.

Base station charging code interval 1107 is followed by 123 preamble burst interval 1109, during which base station 304 transmits a charging code. The transmit / receive switch interval 1104 is followed by the known charging code interval 1107, during which the base station 304 can switch from transmit mode to receive mode. However, if the base station 304 is equipped with independent transmit and receive hardware, the base station does not need to change modes and instead can continue to transmit the charging code during the transmit and receive switch interval 1104.

The special communication exchange shown in the example of FIG. 11B is now described in more detail. In base station frequency band 1170 in a first time slot TS1, the base station transmits a base station to user station message to the first user station M1 within the base station message interval 1103. Base station 304 then transmits the 123 preamble burst to another user station M3 during the 123 preamble burst interval 1109. Simultaneously with base station transmission, the base station 304 takes the preamble from the end user station (MN) with which the base station 304 communicates in the user station frequency band 1171 during the data link preamble interval 1112, and the user station message interval 1113. Receive user station to base station messages. During the control pulse preamble interval 1116 of the first time slot TS1, in the user station frequency band 1171, the base station 304 is the user station M2 that the base station 304 is to transmit to the next time slot TS2. Receive control pulse preamble from.

The function of the control pulse preamble transmitted during the control pulse preamble interval 1116 is similar to that described above with respect to the control pulse preamble of FIGS. 10A-E (eg, power control, antenna adjustment, etc.). The antenna adjustment interval 1117 is followed by the preamble interval 1116 with the opportunity for the base station 304 to adjust the transmit antenna to face the second user station M2 based on the information obtained from the reception of the control pulse preamble if necessary. Another guard band 1118, which is responsible for the transmission time of the control pulse preamble to the base station 304, is followed by the antenna adjustment interval 1117. After the preamble interval, there is another transmit / receive switching interval 1119, which gives the base station 304 an opportunity to switch from the receive mode to the transmit mode and the second user station M2 provides an opportunity to switch from the transmit mode to the receive mode. do.

Using the base station frequency band 1170 in the next time slot TS2 after the first time slot TS1, the preamble is transmitted during the base station preamble interval 1102, and the base station to user station message is transmitted during the base station message interval 1103. It is sent to the user station M2. Accordingly, the base station 304 responds quickly to the control pulse preamble sent by the user station M2. However, assume that in the example time frame 1140 of FIG. 11B the base station 304 did not establish communication with any user station 302 in the base station frequency band 1170 during the fourth time slot TS4. Thus, within the 123 preamble burst interval 1109 following the base station message interval 1103, the base station 304 may not transmit a 123 preamble burst to the user station 302.

Simultaneously with the base station transmission in the second time slot TS2, the base station 304 is a data link preamble in the user station frequency band 1171 from the user station M1 with which the base station 304 communicates in the first time slot TS1. Receive a preamble during interval 1112 and a user station to base station message during user station message interval 1113. Similarly to the first time slot TS1, in the user station frequency band 1171 during the control pulse preamble interval 1116 of the second time slot TS2, the base station 304 causes the base station 304 to have the next time slot ( The control pulse preamble is received from the user station M3, which is the object to be transmitted to TS3).

In a third time slot TS3, the base station 304 uses the base station frequency band 1170 to transmit the preamble during the base station preamble interval 1102 and the base station to user station message during the base station message interval 1103. Send to M3. The 123 preamble burst interval 1109, where the base station 304 sends three short preamble bursts (i.e., 123 preamble bursts) to another user station M5, which intends to communicate after two time slots 1141, is the base station message interval ( 1103).

Simultaneously with base station transmission, the base station performs a preamble during the data link preamble interval 1112 in the user station frequency band 1171 from the user station M2 with which the base station 304 communicated in a preceding time slot TS2, and the user station message interval. Receive a user station to base station message during 1113. Since the base station 304 is not establishing communication with any user station 302 during the fourth time slot TS4 in the base station frequency band 1170, the base station 304 has a third time in the user station frequency band 1171. The control pulse preamble is not received during the control pulse preamble interval 1116 of the time slot TS3.

Similar exchanges are made to the fourth time slot TS4 and subsequent time slots 1141. Whether specific user station to base station messages, base station to user station messages, and preambles or control pulse preambles are transmitted depends on whether base station 304 is communicating with user station 302 requesting such an exchange at a particular time. Depends on whether or not.

Thus, in general, in order to support communication between the user station 302 and the base station 304 communicating during a single time slot 1141, each time frame 1140 between a particular user station 302 and the base station 304 is not present. Four messages are exchanged. Base station 304 first transmits a 123 preamble within 123 preamble interval 1109 of time slot 1141 to which base station 304 attempts to transmit to user station 302 earlier. In another frequency band in the next time slot 1141, the user station 302 responds by transmitting a control pulse preamble received at the base station 304 during the control pulse preamble interval 1116. In the next time slot 1141, after making a decision regarding power coordination and / or timing coordination, base station 304 transmits a base station to user station message during base station message interval 1103 in base station frequency band 1170. 304). In the next time slot 1141, after adjusting the power and / or timing, the user station 304 responds with a user station to base station message received at the base station 304 during the user station message interval 1113.

As noted above, in the exemplary time frame 1140 of FIG. 11B the base station 304 is not establishing communication with any user station 302 during the fourth time slot TS4 in the base station frequency band 1170. Is assumed. Base station 304 may indicate that a particular time slot 1141, such as time slot TS4, may be used for communication, for example, by sending a general purpose polling message during base station message interval 1103 of time slot TS4. .

If the user station 302 wants to establish communication with the base station 304 (as in the fourth time slot TS4), then general-purpose polling during the base station message interval 1103 of the fourth time slot TS4. In response to the base station 304 sending the message, the new user station 302 may send a universal polling response message during the user station message interval 1113 of the next time slot TS5 (not shown). When the new user station 302 responds with a universal polling response message, the base station 304 can determine the range of the user station 302 to determine the timing adjustment required for subsequent transmission by the user station 302. . The base station 304 may then issue periodic timing adjustment commands to maintain reception of user station-to-base station transmissions at the beginning of each user timing interval. Base station 304 may monitor the distance of user station 302 by monitoring the time of receiving a control pulse preamble or user station to base station message from user station 302.

For efficiency, it is desirable to keep guard times 1114 and 1118 to a minimum. The shorter the guard times 1114 and 1118 are, the more user stations 302 can be supported by the frame structure of FIG. 11B. Thus, guard times 1114 and 1118 are usually not long enough for complete ranging processing. In particular, the lasing process may cause disturbances between the transmission of the user station 302 attempting to establish communication and the control pulse preamble of the user station 302 already communicating with the base station 304 in the next time slot 1141. have. If the guard times are extended to allow ranging processing, the user station 302 can hardly be supported, especially in large cell environments. Other structures with improved efficiency in large cell environments with the flexibility of ranging processing are shown in FIGS. 11C and 11D and described in more detail below.

Appropriate timing is preferably set at initial communication establishment, and timing adjustment commands from base station 304 where transmissions from user stations such as first user station M1 are similar to the timing adjustment commands described herein. May be maintained in time alignment when viewed at the base station 304. Since user station 302 and base station 304 transmit on different frequency bands, interference between base station-to-user station messages and user-to-base station messages can be avoided, so each time slot 1141 needs to include a full round trip guard time. There is no.

The diagram of the frame structure of FIGS. 11A-B assumes that the user station 302 is at a distance of zero from the base station, and therefore the user station to base station message appears immediately after the preamble interval 1112 or 1122. However, if the user station 302 is not immediately adjacent to the base station 304, a portion of the guard time 1114 shown in FIG. 11A is responsible for the transmission of the preamble and user station to base station message to the base station 304. Used. Thus, if the user station 302 is in the vicinity of the cell, the user station to base station message should appear at the base station 304 at most after the same time as the duration of the guard time 1114. In order to ensure the guard times 1114 and 1118 are kept to a minimum, a timing adjustment command is preferably sent periodically from the base station 304 so that the user station preamble and the user station without interference with the transmission of the preceding user station 302. The base station message is kept as close as possible to the base station 304 as close as possible to the user station timing subelement 1110.

When ranging processing is supported in the environment of FIG. 11B, the portion of time slot 1141 on user station frequency band 1171 is a lane between the base station 304 and the new user station 302 as described above with respect to FIG. 11A. It may include a range timing sub-element 1121 in which the gong processing is performed. Thus, user station 302 transmits a preamble during ranging preamble interval 1122 of time slot 1141 and a ranging message during user station ranging message interval 1123 of time slot 1141. The user station 302 delays the transmission of the preamble and the lasing message during the time period ΔT. The delay time ΔT may be sent by the base station 304 as part of a universal polling message or may be a preprogrammed system parameter. The base station 304 measures the round trip transmission delay from the user station 302 to the actual reception time of the response preamble and ranging message at the end of the preceding time slot 1141 taking into account the delay time ΔT. Determines the transmission delay to the base station 304 at.

In the above-described embodiment supporting the ranging process, the ranging guard band 1124 preferably has a sufficient length so that ranging processing between the base station 304 and the user station 302 can be performed. Thus, the length of the ranging guard band 1124 may be determined in part by the radius of the cell 303 in which the base station 304 is located, or in part by the maximum cell radius of the cellular system.

In response to receiving the ranging message from the user station 302 and determining the distance of the user station 302 and its transmission delay time, the base station 304 returns to the user station 302 in the next time frame 1140. A timing adjustment command may be issued that instructs the user station 302 to advance or delay its timing by a specified amount. During the time frame 1140 immediately after communication with the user station 302 is established, the timing adjustment command may be set equal to the round trip transmission time determined by the base station 304 during the ranging process. Preferably, the timing adjustment command is selected such that in a subsequent time frame 1140 a user transmission from user station 302 to base station 304 is received by base station 304 immediately after the end of preceding time slot 1141.

In addition to being used for ranging, the ranging message may also include other information to assist in handshaking between the base station 304 and the user station. For example, the ranging message may include, as data, a user identifier for the user station 302 to establish communication with. The ranging message may also indicate a preferred spread spectrum code to be used by the base station 304 and the particular user station 302 in subsequent communications.

The potential interference between the ranging messages and the control pulse preambles can be minimized by using a specific spread spectrum code for only the ranging messages or only the control pulse preambles. However, code division multiplexing in this manner may not provide sufficient isolation between interfering signals or may require unacceptably long time slots.

In the next time slots 1140, after establishing communication with the user station M3 in the manner described above, the base station 304 and the user station M3 are interleaved over several time slots 1140. Communication can be performed. As part of each transmission from the base station 304, the base station 304 may update the timing adjustment command for the user station M3.

When user station 302 terminates communication within time slot 1141, or is connected to a new base station 304, base station 304 may attempt to communicate during time slot 1141 for newly initiated time slot 1141. It can begin sending a universal poll message indicating that it is free. Accordingly, the new user station 302 can establish communication with the same base station 304.

A simple way to adapt an FDD / TDMA system such as that shown in FIG. 11B to emulate a TDD system is to alternately black out time slots in each of the two frequency bands 1170, 1171. Therefore, during the time slot TS1, the base station 304 transmits from the frequency band 1170 to the user station M1, while no transmission is performed in the frequency band 1171. During the next time slot TS2, user station M1 responds in frequency band 1171, while no transmission occurs in frequency band 1170. The next two time slots TS3 and TS4 are used for dual communication between the base station 304 and the next user station M2 with the user station slot at TS3 and the base station slot at TS4 stopped. The described frame structure generally supports fewer user stations 302 than the frame structure shown in FIG. 11B due to the alternating stop of time slots in each frequency band 1170, 1171, but as shown in FIG. 10B. Allow the TDD interface to be emulated at the base station and user station with minimal modification (eg, by sending and receiving in different frequency bands). If both frequency bands 1170 and 1171 are selected identically, then the system is a true TDD, so only the proper selection of the frequency band and the appropriate selection of time slots for transmission on the forward reverse links (i.e. alternative selection) ) Allows the same hardware to perform FDD / TDMA or TDD operations.

11C is a timing diagram for an offset interleaved FDD / TDMA frame structure using the timing subelements shown in FIG. 11A, as shown from a perspective view of base station 304. As shown in FIG. As described below, the offset interleaved FDD / TDMA frame structure of FIG. 11C allows larger cells by allowing the user stations 302 to receive transmissions of the base station towards them prior to the response, and the user station 302 Can eliminate the need for expensive duplexers.

FIG. 11C illustrates the frame structure of a system using two frequency bands for communication in addition to a particular aspect of time division multiple access. The first frequency band 1172, also called the base station frequency band, is mainly used for communication from the base station 304 to the user station 302. The second frequency band 1173, also called the user station frequency band, is mainly used for communication from the user station 302 to the base station 304. Two frequency bands 1172 and 1173 are preferably installed at 80Mhz apart. By separating the 80 MHz frequency, co-channel interference can be minimized, and the configuration of a filter in the receiver can be facilitated in filtering out potentially coherent signals from reverse path communication.

In the frame structure of FIG. 11C, the time frame 1150 includes a plurality of time slots 1151. For convenience, the time slots are designated as sequential numbers to be OTS1, OTS2, OTS3, and the like. Each time slot 1151 has a base timing sub-element on base station frequency band 1170 and a user datalink timing sub-element 1110 or range timing sub-element on user frequency band 1171. 1121). Since the time slot 1151 is shown by a perspective view of the base station 304, the base station timing sub-element 1101 and the user timing sub-elements 1110 and 1121 in FIG. 11C have a predetermined offset time (1160). ) Will be shown staggered. The frame structure of FIG. 11C supports both the range timing sub-element 1121 and the user datalink timing sub-element 1110 on the user station frequency band 1171.

In operation, the base station 304 transmits to the user station 302 in which the base station 304 establishes communication in order as part of the base station timing sub-element of each time slot 1151. In this manner, the base station 304 transmits the preamble during the preamble period 1102 and the base station to user station message during the base station message period 1103. After the base station message period 1103, the base station 304 transmits three short preamble bursts within the 123-preamble burst period 1109 directed to another user station 302. In the example system of FIG. 11C, three preamble bursts during the 123-preamble burst period 1109 are directed to the user station 302 where the base station 304 sends out a main data message after two time slots 1151.

As in the case of the system of FIG. 11B, three short preamble bursts issued during the 123-preamble burst period 1109 may be used for forward link diversity detection and forward link power control purposes. Each of these three preamble bursts gives the user station 302 transmitted and received via the other antenna an opportunity to make diversity selection for upcoming forward link data messages during subsequent time slots 1151.

After 123-preamble burst period 1109 is base station fill code period 1107 through which base station 304 transmits a fill code. After base station code fill period 1107 is a transmit / receive switch period 1104 in which base station 304 may switch from transmit mode to receive mode. However, if base station 304 has separate transmit and receive hardware, there is no need to switch modes. Instead, the base station 304 may continue to transmit the fill code during the transmit / receive switch period 1104.

Hereinafter, the specific communication exchange shown as an example in FIG. 11C will be described in more detail. During the first time slot OTS1 on base station frequency band 1172, the base station transmits a base station to user message within base station message period 1103 directed to first user station M1. The base station 304 then transmits a 123-preamble burst during the 123-preamble burst period 1109 directed to another user station M3. Although offset from the base station's transmission by an offset time 1160, at the same time as the base station's transmission, the base station 304 draws the preamble during the datalink preamble period 1112 on the user station frequency band 1175, and the user message period ( During 1113, base station 304 receives a user station to base station message from an end user station (MN) in communication. During the control pulse preamble period 1116 of the first time slot OTS1 on the user station frequency band 1173, the base station 304 receives the control pulse preamble from the user station M2 that the base station 304 intends to transmit during the next time slot OTS2. Receive.

The functions of the control pulse preamble issued during the control pulse preamble period 1116 are similar to those described above in connection with the control pulse preambles (eg, power control, antenna adjustment, etc.) of FIGS. 10A-E and 11B. After preamble period 1116 is an antenna adjustment period 1117 where the base station 304 has the opportunity to adjust its transmit antenna if necessary. After the antenna adjustment period 1117, the control pulse preamble is transmitted to the base station 304 to direct its transmit antenna toward the second user station M2 based on the information obtained from the reception of the control pulse preamble. Guide band 1118. After the preamble, another transmit / receive switch that provides the base station with the opportunity to switch from the receive mode to the transmit mode if necessary, and gives the second user station M2 an opportunity to switch from the transmit mode to the receive mode. Period 1119.

Within the next time slot OTS2 after the first time slot OTS1, the base station 304 uses the base station frequency band 1172 to perform the preamble during the base station preamble period 1102, which is both directed to the second user station M2. And base station-to-user station messages during base station message period 1103. Accordingly, the base station 304 quickly responds to the control pulse preamble sent by the user station M2. However, in the example time frame 1150 of FIG. 11, it is assumed that no communication is established with any user station 302 during the fourth time slot OTS4 over the base station frequency band 1172. Thus, in the 123-preamble burst period 1109 involving the base station message period 1103 during the second time slot OTS2, the base station 304 cannot transmit the 123-preamble burst directed to the user station 302.

Simultaneously with the transmission of the base station in the second time slot OTS2 offset from the transmission of the base station by the offset time 1160, the base station 304 performs a preamble and a preamble during the datalink preamble period 1112 on the user station frequency band 1175. During the user message period 1113, a user to base station message is received from the user station M1 to which the base station 304 communicated in the first time slot OTS1. Similar to the first time slot OTS1, the base station 304 during the control pulse preamble period 1116 of the second time slot OTS2 on the user station frequency band 1173 causes the base station 304 to transmit during the next time slot OTS3. A control pulse preamble is received from M3.

During the third time slot OTS3, the base station 304 uses the base station frequency band 1172 to preamble during the base station preamble period 1102, which is both directed to the third user station M3, and the base station message period 1103. While transmitting a base station-to-user message. After the base station message period 1103, the base station 304 may have three short preamble bursts (ie, 123-preamble bursts) directed to another user station M5 to which the base station 304 will communicate after two slots 1151. ) Is a 123-preamble burst period.

Simultaneously with the transmission of the base station offset from the transmission of the base station by the offset time 1160, the base station 304 performs a preamble on the user station frequency band 1171 during the data link preamble period 1112 during the user station message period 1113. 304 receives a user station to base station message from user station M2 that communicated in a previous time slot OTS2. Since the base station 304 does not establish communication with any user station 302 during the fourth time slot OTS4 over the base station frequency band 1172, the base station 304 is controlled on the user station frequency band 1173. The control pulse preamble is not received during the control pulse preamble period 1116 of the three time slots OTS3.

Similar exchanges are also made during the fourth time slot OTS4 and during the next time slot 1151. Whether a particular user station to base station message, a base station to user station message, and a preamble or control pulse preamble is transmitted is whether the base station 304 is in communication with the user station 302 requesting the exchange at a particular time. By

Thus, in order to support communication between a user station 302 and a base station 304 that are generally communicating during a single time slot 1151, during each time frame 1151 between a particular user station 302 and the base station 302. Four messages are exchanged. The base station 304 first transmits a 123-preamble during the 123-preamble period 1109 of the time slot 1151 before the two time slots 1151 that the base station 304 is trying to transmit to the user station 302. The user station 302 transmits a control pulse preamble received by the base station 304 during the control pulse preamble period 1116 during the time slot 1151 after being delayed by an offset time 1160 on another frequency band 1175. do. After making a decision about power coordination and / or timing coordination during the next time slot 1151, base station 304 sends a base station to user station message to user station 302 during base station message period 1103 on base station frequency band 1172. Send. After adjusting its power and / or timing during the next time slot 1151, the user station 304 responds with a user station to base station message received at the base station 304 during the user message period 1113.

In the example time frame 1150 of FIG. 11C, it is assumed that the base station 304 is not establishing communication with any user station 302 during the fourth time slot OTS4 over the base station frequency band 1172. Base station 304 indicates that a particular time slot 1151, such as time slot OTS4, may communicate by sending a general polling message, for example, during base station message period 1103 of time slot OTS4. can do.

If the user station 302 wishes to establish communication with the base station 304 (as in the fourth time slot OTS4), transmit a general polling message during the base station message period 1103 of the fourth time slot OTS4. In response to the base station 304, the new user station 302 may send a generic polling response message during the user station message period 1113 of the next time slot OTS5. When the new user station 302 responds with a generic polling response message, the base station can determine the range of the user station 302 and accordingly determine the timing adjustment for subsequent transmissions needed by the user station 302.

In terms of efficiency, the guidance times 1114 and 1118 are preferably kept to a minimum. The smaller the guide times 1114 and 1118, the more the user station 302 can benefit from the frame structure of FIG. 11C.

Appropriate timing is preferably set after initial communication establishment, and transmission from a user station such as the first user station M1 is applied to a command of timing adjustment from the base station 304 similarly to the timing adjustment command disclosed herein. It can be maintained by the time adjustment known by the base station. Since the user station 302 and the base station 304 are transmitted on different frequency bands, there is no need to include a full round trip time during each time slot 1151, thereby preventing interference between the base station to user station messages and the user station to base station messages. Can be.

The form of the frame structure of Figure 11C (i.e., disassembled time slot 1151) assumes that user station 302 is at a distance corresponding to zero from base station 304. However, user station 302 is a base station (i.e. If not immediately adjacent to 304, a portion of the announcement time 1114 is consumed in the delivery of the preamble and user station to base station messages to the base station 304, as shown in Figure 11a. If 302 is around the cell, the user station to base station message will appear at base station 304 after the elapse of time period is approximately equal to the duration of the announcement time, announcement times 1114 and 1118 remain minimal. In order to ensure that the preamble of the user station and the user station to base station message reaching the base station 304 without interfering with the transmission of the previous user station 302, the timing sub-element 1110 of the user station is possible. Similarly, to maintain and it is preferable that the timing adjustment command is periodically transmitted from the base station 304.

First, when the user station 302 establishes communication with the base station 304 in the frame structure of Fig. 11C, a range-defining transaction is performed. The time slot 1151 on the user station frequency band 1171 where the ranging transaction is initiated preferably includes a range timing sub-element 1121 as described above in connection with FIG. 11A. User station 302 transmits a preamble during range preamble period 1122 of time slot 1151 and transmits a range message during range message period 1123 of user station in time slot 1151. User station 302 delays transmitting the preamble and range messages for the amount of time ΔT. This delay amount ΔT may be a system parameter communicated by the base station 304 or preprogrammed as part of a general polling message. The base station 304 measures the round trip propagation delay from the user station 302 to the actual reception time of the responsive preamble and range message at the end of the previous time slot 1151, taking into account the delay amount ΔT. Determines the propagation delay from the base station to the base station 304.

The range guide band 1124 must be of sufficient length to allow range transactions between the base station 304 and the user station 302. Thus, the length of the range guide band 1124 may be determined in part by the radius of the cell 303 in which the base station 304 is located, or in part by the maximum cell radius of the cellular system.

Base station 304 receives a range message from user station 302 to determine the distance of user station 302 and / or propagation delay time therefrom and to timing user station 302 during the next time frame 1150. An adjustment command is issued to advance or delay its timing by a specified amount. The timing command may be set equal to the round trip transfer time determined by the base station 304 during the range transaction during the time frame 1150 immediately after communication with the user station 302 is established. The timing adjustment command is selected such that transmission of the user station from the user station 302 to the base station 304 in a subsequent time frame 1150 is received by the base station 304 shortly after the end of the previous time slot 1151. desirable.

The range message may include other information that assists the base station 304 in handshaking with the user station 302 in addition to being used for the purpose of determining the range. For example, the range message may include as user data the user identifier for the user station 302 to establish communication with. The range message may indicate the desired spread spectrum code used by the base station 304 and the particular user station 302 in subsequent communications.

It may also be possible to minimize the potential interference between the range message and the control pulse preamble using spread spectrum codes specifically designated for the range message only or for the control pulse preamble only. However, in most cases user stations 302 are sufficiently separated by time-related transmissions using offset time 1160 between base station frequency band 1172 and time slot 1151 on user station frequency band 1171. It is expected that the system can be made to minimize the interference between them.

An advantage of the frame structure of FIGS. 11C-D using offset time 1160 is that a deplexer, i.e., a device capable of simultaneous transmission and reception of signals, is not required in the user station 302. On the other hand, in the fixed offset frame structure of FIG. 11B, the user station 302 during time slot 1141 prior to receiving the entire base station to user station message, which is to be sent during the previous time slot 1141, especially in large cell environments. ) Needs to transmit, so you may need a deplexer to support dense users. Since FIG. 11B is constructed from a perspective view of the base station, a time slot 1141 is connected to the base station 304, but the time is transmitted to the user station 302 so that information arrives at the connected base station 302 as shown in FIG. 11B. It is required to transmit the information of the user station before the user portion of the slot 1141. In large cell environments where the user station 302 is remote, the user station 302 may be required to send its information prior to receiving the entire base station to user station message. This may require a deflector because the user station needs the ability to transmit and receive information simultaneously. For protocols that require user station 302 to receive base station messages prior to response, the system of FIG. 11B is not suitable in large cell environments.

In the embodiment of FIGS. 11C-D, the time slot 1151 on user frequency band 1171 is offset from that on base station frequency band 1172 by an offset time 1160. The offset time 1160 allows the base station to user station's message to be delivered to the user station 302 prior to the transmission of the user station to base station message by the user station 302. As a result, the user station 302 does not require a deplex, which is a relatively expensive component. When the user station 302 is realized as a mobile handset, it is particularly advantageous to operate without deflex since it is important to keep the manufacturing cost of the handset as low as possible. Other hardware effects can be achieved because they do not require simultaneous transmission and reception, for example, user station 302 can use the same frequency synthesizer for both transmission and reception functions.

FIG. 11D shows a subsequent time frame 1150 after the range transaction is completed with the third user station M3. In FIG. 11D, the transactions between the user stations M1 and MN and the base station 304 generated in the first time slot OTS1 are the same as those in FIG. 11C. In addition, the transactions between the user stations M1 and MN and the base station 304 generated in the second time slot OTS2 are the same as those in FIG. 11C. However, since there is no control pulse preamble transmitted during the preamble period 1161 during the second time slot OTS2, the third user station M3 performs the control pulse preamble during the preamble period 1116 of the second time slot OTS2. I can send it. In contrast, the user station M3 transmits its range message sent in the previous time frame 1150 before the base station 304 transmits the control pulse preamble during the preamble period 1116 of each preceding time slot OTS2. It may wait until 304 is approved.

After establishing communication with the third user station M3 by the method described above in the next time frame 1150, communication between the base station 304 and the user station M3 can be made as shown in FIG. 11D. The base station 304 may update the timing adjustment command for the user station M3 as part of each transmission from the base station 304.

If user station 302 terminates communication in time slot 1151 or is handed off to a new base station 304, then base station 304 indicates that the newly established time slot indicates that time slot 1151 has been released from communication. During 1115, a generic polling message may begin to be sent. This allows the new user station 302 to establish communication with the same base station 304.

12A-C are tables showing preferred message formats for transmission of base stations and user stations. Tables 12b-1 to 12b-3 show the message formats for transmission used in handshaking or acquisition modes. Tables 12c-1 to 12c-4 show the message formats (symmetrical and asymmetrical) after capture in the traffic mode. It should be noted that the asymmetric message format is intended for use in TDD-enabled system variants, not for FDD-enabled systems. Tables 12a-1 through 12a-4 show the header format of each of the other message types in Tables 12b-1 through 12c-4.

For example, table 12a-1 illustrates a header format for base station polling transmission (general or special case) described above. The header format of Table 12a-1 includes 12 bits. The special header format contains 10 fields totaling 19 bits minus two spare bits. These fields are a 1-bit B / H field that identifies whether the transmission source is a base station or a user station, a 1-bit E field that can be used as an extension of this B / H field, and a 1 indicating whether the polling message is generic or special. G / S field of bits, 1 bit P / N field indicating whether transmission is a polling or traffic message, 1 bit SA field for checking and verifying, 3 bit PWR field for power control, 2 indicating slot availability CU field of bits, a 2-bit counter link quality field that indicates how well the sender is receiving the reverse sense link, a 3-bit timing adjustment command that provides commands to the user station to adjust timing if necessary, and errors A 4-bit header FCW (Frame Check Word) field for detection (similar to CRC).

The header format for base station traffic transmission is shown in Table 12a-2. The header format is the same as that in Table 12a-1, but if there are exceptions, there are two bits of additional B / W grant fields to allocate additional bandwidth to user station 302 through the use of time slot sets or asymmetric time slots. Is that there is. The header format of Table 12a-2 uses 12 bits.

Header formats for mobile or user polling transmissions are shown in Table 12a-3. This header format is similar to that of Table 12a-1 except that it does not contain a CU field or a timing command field. In addition, the header format of Table 12a-3 includes a 1-bit B / W request field for the request of additional bandwidth or time slot. The table 12a-3 header format includes six reserved bits.

Header formats for mobile or user traffic transmission are shown in Table 12a-4. The header format of Table 12a-4 is the same as that of Table 12a-3 except that the B / W Request field is specified in place of the B / W permission field.

Thus, the header format for the user station 302 and the base station 304 is selected to be the same length in the example embodiment described in connection with FIGS. 12A-C, whether polling or traffic mode, and whether the polling message is a general or special type.

Tables 12b-1 to 12b-3 show the message formats for transmission used in the handshaking or acquisition mode. Table 12b-1 shows the 205 bit message format for general polling transmission of the base station. The message format of Table 12b-1 includes a 21-bit header field that includes the fields shown in Table 12a-1, which are 32-bit fields for identifying the base station 304 transmitting the general polling message. Various networks, such as a base station ID field, a 16-bit service provider field that can be used to indicate a telephone network or other communication source, a 16-bit zone field that can be used to identify a paging cluster, and a 32-bit facility field. And a system identification field, a 6-bit slot number field indicating the slot number of the general polling transmission associated to contribute to the user station 302 synchronously, and a 16-bit frame FCW field for error correction and flawless transmission verification.

The 150 bit message format for mobile or user station response transmission is shown in Table 12b-3. The message format of Table 12b-3 includes a 21-bit header field that contains the fields shown in Table 12a-3, which are 40-bit bits that identify the user station 302 that responds to a general polling message. PID field, 16-bit service provider field, 16-bit service request field indicating which of the various services available from the base station 304 are being requested, 8-bit mobile capacity field, and 16-bit frame FCW field. . The mobile capacity field is a two sub-field, in 2-bit form or capacity sub-field indicating the capacity of the user station (e.g., a deplex that interleaves traffic slots), and the slot number of the general polling transmission of the base station. And a 6-bit home base station slot number field for echoing the slot number received from the field. The 150-bit user station polling response transmission is substantially shorter than a base station polling transmission or traffic message transmission considering the unspecified initial propagation delay time from the user station 302 wishing to establish range communication and establish communication.

The message format of 205 bits for the specific polling transmission of the base station is shown in Table 12b-2. The message format of Table 12b-2 includes a 21-bit header field that includes the fields shown in Table 12a-1, which include an 8-bit correlation ID field, an 8-bit result field, 40-bit PID field for echoing the identification number received from the user station 302, 8-bit mapped field representing the time slot number of the particular base station 304, slot is in use (potentially used by user station 302) 32-bit map field, 6-bit slot number field, and 16-bit frame FCW fields.

Tables 12c-1 to 12c-4 show the message formats (symmetrical and asymmetrical) after capture in the traffic mode. Tables 12a-1 and 12a-2 are base station traffic mode message formats, the message formats of table 12a-1 are used for symmetric frame structures, and the formats of table 12a-2 are used for asymmetric frame structures. Similarly, tables 12a-3 and 12a-4 are mobile or user station traffic mode message formats, the message formats of table 12a-3 are used for asymmetric frame structures, and the formats of table 12a-4 are used for asymmetric frame structures. .

In a symmetric frame structure, each traffic mode message is 205 bits long, and each traffic mode message is a D-channel with low data rate messaging capability of 8 bits in length depending on whether a 16-bit frame FCW field is used. Field (or data field) and a B-channel field (or bearer field) of 160 or 176 bits in length.

In an asymmetric frame structure used only for the TDD system variant, traffic mode messages from one source are generally very long different lengths than traffic mode messages from another source. An asymmetric frame structure can make the data bandwidth much higher in one direction of the communication link than the other direction of the communication link. Thus, one traffic mode message is 45 bits long while the other traffic mode message is 365 bits long. The total length of the forward and reverse link messages amounts to a total of 410 bits, as in the case of the symmetric frame structure. Each traffic mode message is a D-channel field (or data field) with low data rate messaging capability of 8 bits in length, depending on whether the sources have the same high transmission rate and whether 16-bit frame FCW fields are used. And a B-channel field (or bearer field) of length 0, 16, 320, or 336 bits.

Base station and user station messages are preferably sent using M-related encoding techniques. The base station and user station messages are preferably composed of a series of contiguous data symbols, where each data symbol corresponds to 5 bits. The spread spectrum code, or symbol code, is transmitted for each symbol. Thus, the transmitted symbol code represents all or part of the data field, or a plurality of data fields, or parts of more than one data field of a base station or user station message.

Since the processing load is generally increased in proportion to the length of the preamble requiring asynchronous processing, a cascading preamble code structure similar to that used for the MPRF mode of the APG-63 radar can be used for the various communication interfaces described herein. . For a general description of APG-radar, see Morris, Airborne pulsed Doppler Radar (Artech House 1988).

13A-B are diagrams illustrating the configuration of concatenated preambles. In FIG. 13A the length 112 preamble code is formed by taking the kronecker product between the Barker-4 (B4) code 1302 and the Minimum Peak Sidelobe-28 (MPS28) code 1301. In one sense, the final preamble can be thought of as an MPS28 code where each chip is substantially a B4 sequence. One advantage of the preamble structure is the 28 non-zero tap MPS28 as shown in FIG. 13B. [1, 0, 0, 0] can be achieved using a 4-tap B4 matched filter 1310 with matched filter 1311. In dealing with the complexity, the technique of Figs. 13A-B is equivalent to a 32-step match filter except that a high speed memory is required. Performance can be improved by implementing the first stage filter 1310 as a mismatched filter instead of a matched filter, thereby reducing side lobes in the filter response.

13D and 13E are graphs comparing filter responses for cascading preambles using matched and unmatched filters, respectively. Assume a length 140 preamble for the purposes of FIGS. 13D and 13E. This preamble contains the kronecker enemy between the Barker-5 (B5) code and the MPS28 code. FIG. 13D illustrates an MPS28 processed by a 5-tap B5 matched filter 1310 with a 28-tap MPS28 matched filter 1311. B5, a composite filter response for a length 140 preamble is shown. Four sidelobe spikes 1320 of about −14 db are apparent in the graph of FIG. 13D. FIG. 13E illustrates the composite filter response for the same preamble processed by the 17-tap B5 unmatched filter 1310 with the 28-tap MPS28 matched filter 1311 with the sidelobe spike 1320 removed in FIG. 13D. will be.

As another processing mechanism, m of the n detectors can be used for detection alarm purposes, while the full length preamble is used for detection confirmation and channel sensing / equalization purposes. The codeset can be generated with a preamble using another MPS28 code showing low cross-correlation characteristics. The potential limitation with this approach is that there are only two MPS28 codewords. Thus, to generate an n = 7 code reuse pattern, a near MPS28 codeword may be included such that a potentially possible preamble showing the desired cross-correlation is expanded. The two MPS28 codewords have a potential peak sidelobe level of 22.9db, while the near MPS28 codewords have a potential peak sidelobe level of -19.4dB.

The preamble processing using control pulse preamble (eg, in preamble period 1016) and 123-preamble message transmission described above with reference to FIGS. 10A-11D will be discussed in more detail. The control pulse preamble and 123-preamble transmissions generally have a fixed timing with respect to the initial preamble transmission (eg, in the preamble period 1002 or 1102) preceding each main user station and base station transmission, in particular Two full length preamble transmissions may be used to aid in synchronization on the reverse link associated with each main user or base station transmission. The preamble length has a dual effect in that it processes both the control pulse preamble or the 123-preamble and the preambles that precede the main user or base station transmission.

14-17 are charts comparing various performance aspects of selected high tier and low tier air interfaces embodying the specified features of the embodiments disclosed herein. With the high tires described above, it is accepted that the system coverage is wide and thereby the capacity is reduced. Conversely, furnace tires are applied to telecommunications services with local high capacity and / or special needs. In one way, users are assigned to the lowest possible tire to conserve capacity with high tires.

In general, high tires are covered by relatively large cells that provide umbrella coverage and continuity. Here the user has a high measurement mobility (eg a high speed vehicle). High tire operation may also be characterized by high transmit power at the base station, high gain receive antennas, and high elevation antenna placement. Factors such as delay spread (which results from multiple propagation delays due to reflections) and horizontal phase center separation applied to multipath and antenna diversity can be significant. For example, the complexity and aperture size due to antenna increase can be important against the use of multiple diversity antennas in high tire applications. Receiver sensitivity can also be an important limiting factor. Receiver sensitivity can also be an important limiting factor. Small coherence bandwidths allow spread spectrum waveforms to be supported in high tier applications.

Low tier applications are generally characterized by smaller cells with coverage limited by the number of physical obstacles and radiation centers rather than receiver sensitivity. Small delay spreads allow for high symbol rates and support antenna diversity techniques to overcome multipath fading. Spread spectrum or narrowband signals may be used, and narrowband signals may be advantageous to achieve high capacity spot coverage and dynamic channel allocation. Dynamic channel allocation algorithms are supported to allow for relatively small reuse patterns by providing quick response to changing traffic requirements and utilizing physical obstacles. Low layer applications may include, for example, wireless local loops, spot coverage for holes in high coverage, localized high capacity, and wireless Centrex.

While certain general characteristics of high and low layer applications have been described above, these items as applied herein are not intended to limit the applicability of the principles of the present invention as set forth in the various embodiments. The classification as high or low is merely to facilitate the description of the exemplary embodiments described herein and to provide useful milestones in system design. High or low name names do not necessarily exclude each other, nor necessarily all possible communication systems.

High and low layer names may apply to operations in the licensed or unlicensed frequency band. In the unlicensed isochronous band (1910-1920 MHz), FCC rules essentially require TDD or TDMA / FDD hybrid because of the narrow available frequency range with a maximum signal bandwidth of 1.25 MHz. Listen before talk capability is generally required to detect and avoid transmission of other users before transmission. Applications in the isochronous band are typically low layer variable and include wireless PBXs, smart badges (eg, positioning devices and passive RF radiating devices), home radios, and compressed video distribution. Due to FCC requirements, dynamic channel allocation and low layer structure are desirable. Also, the power limit generally excludes large cells.

In the Industrial Scientific Medical (ISM) band (2400-2483.5 MHz), applications are similar to the unlicensed isochronous band, except that federal rules are somewhat less restrictive. Spread-spectrum techniques are typically preferred to minimize transmit power where a processing gain of at least 10 dB is required (eg, up to 1 watt). Because of the small frequency range of the ISM band, TDD or TDMA / FDD hybrid structures are preferred.

14 is a summary table comparing various air interfaces, generally classified by high and low floor names. The first column of FIG. 14 identifies the air interface type. The air interface type is chip rate, tier, and frame structure-TDD (single frequency band by time division), as described above with reference to FIGS. 10A-10E and 11A-11D, or It is identified by FDD / TDMA (multiple frequency bands by time division). Thus, for example, the identifier 5.00HT that appears in the first row of the first column of the table of FIG. 14 identifies that the air interface has a chip rate of 5.00 megachips (Mcp), is high-layer, and has a TDD structure. Similarly, the identifier 0.64LF appearing in the sixth row of the first column identifies the air interface as having a chip rate of 0.64 Mcp, low layer, and having an FDD / TDMA structure. A total of 16 different air interfaces (10 high and 6 low) are summarized in FIG. 14.

The second column of the table of FIG. 14 identifies the duplex method, also indicated above, indicated by the last initial of the air interface type. The third column of the table of FIG. 14 identifies the number of time slots for each particular air interface type. In certain embodiments, the range of time slots is from 8 to 32. The fourth column of the table of FIG. 14 identifies the chip rate (in MHz) for each particular air interface type. The fifth column of the table of FIG. 14 identifies the number of channels in each allocation, which is an approximation of the number of RF channels that can be supported in a particular bandwidth allocation and may vary with the selected modulation technique and chip rate. The sixth column of FIG. 14 shows the sensitivity (in dBm) measured at the antenna post. The seventh and eighth columns of the FIG. 14 table represent the number of base stations required in different propagation environments, with 100% as the reference setting for the 5.00HT air interface. Propagation environments considered in the FIG. 14 table include R ² (open area), R ⁴ (shown), and R ⁷ (low antennae show), as listed.

The air interface types of FIG. 14 are also classified into four general categories, including high, low, unlicensed isochronous, and ISM air interface types. High-rise operation takes antenna diversity (L _ant ) with two antennas, two resolvable multiple multipaths (L _rake ), and 30 MHz bandwidth allocation. The number of resolvable multipaths is generally a function of receiver performance, delay spread and antenna placement. Low layer operation takes antenna diversity using three antennas, a single resolvable communication path, and a 30 MHz bandwidth allocation. Unlicensed isochronous operation takes antenna diversity with three antennas, a single resolvable communication path, and a 1.25 MHz channel bandwidth. ISM operation takes antenna diversity using three antennas, a single resolvable communication path, and an 83.5 MHz bandwidth allocation.

FIG. 15 compares the digital range limits (in miles) for the air interfaces described in FIG. 14. The digital range depends, in part, on the number of time slots employed and whether ranging (ie timing adjustment control) is used. The multiple columns under the ranging heading used indicate whether timing control is implemented in the system and correspond in the same order to the multiple columns under the time slot heading indicating the number of time slots used. Multiple columns under the digital range heading correspond in the same order to the columns under the ranging and time slot headings used. Thus, for example, for a 5.00HT air interface, three possible embodiments are shown. The first embodiment uses 32 time slots and ranging (timing adjustment) to have a digital range of 8.47 miles. The second embodiment uses 32 time slots and no ranging, resulting in a digital range of 1.91 miles. The third embodiment uses 25 time slots and no ranging, resulting in a digital range of 10.06 miles.

From the example system parameters shown in the FIG. 15 table, reduce the number of time slots used, increase the chip rate, use multiple frequency bands (ie, use FDD and TDD techniques), It can be observed that the digital range can be increased by using ranging (timing adjustment).

FIG. 16 is a table describing the impact on base station-user initial handshaking negotiation and time slot aggregation of various air interface structures. The parameters considered in FIG. 16 include whether the base station 304 operates in ranging or non-ranging mode, whether the user station 302 has a duplexer, and whether the forward link antenna probe signal is employed. And whether or not interleaved traffic streams are supported. The number of base station time slots that must occur between each communication is shown under the heading Number of base station slots prohibited. The number is the initial acquisition transactions appearing under the GP / SP negotiation (GP indicates a generic polling message, and SP indicates a specific polling message as described earlier in this document) subheading, and the traffic mode that appears under the same mobile station traffic slot heading. It is different for transactions. The latter number determines the maximum set of slots that appear in the last column (as a percentage of the total time frame).

From the table of FIG. 16, it can be seen that to support ranging transactions, the system needs to consider the delay in the initial acquisition transactions. In addition, the ability to support ranging transactions can also affect slot aggregation possibilities. This effect can be mitigated or eliminated by supplying a duplexer to the user station 302 so that the user station 302 can transmit and receive signals simultaneously.

Tables A-1 through A-28 present exemplary high and low air interface specifications in more detail. In particular, specifications are provided for air interfaces labeled 5.00 HT, 2.80 HT, 1.60 HT, 1.40 HT, 0.64 HT, 0.56 HT, and 0.35 HT in various configurations.

13C is a table comparing preamble detection performance in high and low layer environments for a number of different air interfaces described above. Longer preambles may be desired (especially in higher-level applications) for asynchronous code separation. Shorter preambles may be sufficient for selected non-diffusion low and unlicensed isochronous environments (especially when larger average N reuse patterns are employed).

The FIG. 13C table tabulates the preamble detection performance in Rayleigh fading, taking the use of three antennas and employing antenna diversity techniques and the strongest of the three antenna signals being selected for communication. For preamble detection, it is desirable to have at least 99.9% detectability to ensure reliable communication and to prevent the preamble from becoming a link performance limiting factor. Antenna probe detection does not need to be so reliable because antenna probe detection is used only in diversity processing, and thus failure to detect antenna probe signal results in only a power increase command on the forward link.

With respect to each air interface type listed in the FIG. 13C table, an exemplary preamble codeword is provided in its second column, and its fourth main column (three antennas in three antenna diversity). An exemplary antenna probe codeword length is provided for each of the probe signals. Codeword lengths are provided in units of chips. The third and fourth main columns of the FIG. 13C table compare the detection performance for the 99.9% detection threshold and the 90% detection threshold, respectively, for the absence of sidelobes and the case of the -7 dB peak sidelobe. As the preamble codeword length decreases, relative cross-correlation power levels (ie, power difference between peak autocorrelation power level and cross-correlation power level) increase. Thus, the FIG. 13C table shows that raising the detection threshold to reject cross-correlated sidelobes from other transmitters also results in degradation of preamble detection performance. Higher preamble detection thresholds may require higher signal-to-noise ratios for the system.

The foregoing has described a flexible, highly adaptable air interface system applied to TDD and FDD / TDMA operations employing spread spectrum or narrowband signal technology or both. Basic timing elements for ranging transactions and traffic mode exchange, including preparation for the control pulse preamble, are used to define the appropriate frame structure. As described with reference to FIGS. 10A and 11A, the basic timing elements are slightly different for TDD and FDD / TDMA frame structures. As mentioned above, the basic timing elements may be used in a fixed format or an interleaved format, and may be used in a zero offset format or an offset format. Frame structures are suitable for use in high or low layer applications, and a single base station or user station may support one or more frame structures and one or more modes (e.g., spread spectrum or narrow band, or low or high layer). .

There are advantages to both TDD and FDD / TDMA air interface structures. The TDD structure more easily supports asymmetric data rates between the forward and reverse links by shifting the ratio of timelines assigned to each link. The TDD structure allows antenna diversity at base station 304 to be achieved for both forward and reverse links because the propagation paths are symmetrical for multipath fading (not necessarily an interfering signal). The TDD architecture also allows for simpler phased array antennas in high gain base station installations since separate forward and reverse link composite structures are not needed. In addition, TDD systems can better share frequencies with existing fixed microwave (OFS) users because fewer frequency bands are needed.

The FDD / TDMA structure can reduce adjacent channel interference caused by other base station or mobile station transmissions. FDD / TDMA systems generally have 3 dB better sensitivity than similar TDD systems, thus potentially requiring fewer base stations and lower deployment costs. In the FDD / TDMA structure, since half symbol rate is used as compared with TDD, sensitivity to inter-signal interference due to multiple paths can be reduced. In addition, mobile devices in FDD / TDMA systems use less power and have lower manufacturing costs because the bandwidth is divided, the D / A and A / D conversion rates are divided, and the RF related signal processing elements operate at half speed. Holding FDD / TDMA systems require less frequency separation between adjacent high and low layer operations and allow base stations to operate without global synchronization (especially in the case of low layer modes). In an FDD / TDMA system, the digital range can also be increased because the timelines are doubled as shown.

18 is a block diagram of a particular low pass IF digital correlator used in a receiver operating in connection with the air interface structures disclosed herein. However, various different correlators may be suitable for use in the various embodiments disclosed herein. In the FIG. 18 correlator, the received signal 1810 is supplied to an analog to digital (A / D) converter 1811. The A / D converter 1811 preferably performs one or two bit A / D conversion and operates at approximately four times the code rate or more. Thus, if the code rate is 1.023 MHz to 10.23 MHz, the sample rate of the A / D converter 1811 will range from 4 to 50 MHz.

The A / D converter 1811 outputs a digitized signal 1812, which is connected to two multipliers 1815 and 1816. Carrier Numerical Control Oscillator (NCO) block 1812 and vector mapping block 1820 work together to provide frequencies suitable for demodulation and downconversion to low-pass IF frequencies. The vector mapping block 1820 outputs a sine signal 1813 and a cosine signal 1814 at the selected conversion frequency. The sine signal 1813 is connected to a multiplier 1815 and the cosine signal 1814 is connected to a multiplier 1816 to generate an I IF signal 1830 and a Q IF signal 1831. I IF signal 1830 is connected to I multiplier 1842 and Q IF signal 1831 is connected to Q multiplier 1843.

Code NCO block 1840 and code mapping block 1840 work together to provide a selected spread spectrum code 1846. The selected spread spectrum code 1846 is coupled to both I multiplier 1842 and Q multiplier 1843. The output of I multiplier 1842 is connected to I summer 1844, which counts the number of matches between the I IF signal 1030 and the selected spread spectrum code 1846. The output of the Q multiplier 1843 is connected to a Q summer 1845, which counts the number of matches between the Q IF signal 1031 and the selected spread spectrum code 1846. I summer 1844 outputs I correlation signal 1850, and Q summer 1845 outputs Q correlation signal 1851.

A zero IF digital correlator may be used in place of the low IF digital correlator. The zero IF digital correlator performs separation of I and Q before A / D conversion, thus requiring the use of two A / D converters instead of one. A / D converters for a zero IF correlator may operate at a code rate instead of four times the code rate as the A / D converter 1811 does.

19A is a block diagram of an exemplary dual mode base station that is operable over multiple frequencies and has both spread spectrum and narrowband communication capabilities. The base station block diagram of FIG. 19A includes a frequency plan architecture for use with the low pass IF digital transceiver ASIC 1920. The base station may employ an FDD technique in which user stations 302 transmit at a low frequency duplex frequency and base station 304 transmit at a high frequency duplex frequency. The base station of FIG. 19A is preferably, for example, Kopta, New Universal All Digital CPM Modulator, IEEE Trans. A direct synthesis digital CPM modulator such as described in COM (April 1987) is used.

The dual mode base station of FIG. 19A preferably includes an antenna 1901 operable in the 2 GHz frequency range. An antenna 1901 is connected to the duplexer 1910, which allows the base station to transmit and receive signals simultaneously via the antenna 1901. Transmit and receive signals are converted to appropriate frequencies generated by multiplying or dividing the master clock frequency output from the master oscillator 1921. The master oscillator 1921 generates a master frequency (e.g., 22.4 MHz), which is provided to the clock divider circuit 1922 that divides the master frequency by a predetermined factor, e.g., 28. The master oscillator 1921 is also connected to another clock divider circuit 1926, which divides the master frequency into a programmable parameter M that is determined by the physical layer on which the base station operates. If necessary, the output of the clock divider circuit 1926 is further divided by another clock divider 1927 by dividing by the programmable parameter M2 to support the second mode of operation through the other physical layer.

The signals to be transmitted are provided by an AISC 1920 to a digital to analog (D / A) converter 1933, which is coupled to a signal from the clock division circuit 1926. It is clocked by. The output of the D / A converter 1933 is connected to a low pass filter 1934 that smoothes the signal envelope. Low pass filter 1934 is connected to multiplier 1936. The output from clock divider circuit 1922 is connected to frequency multiplier circuit 1935, which multiplies its input by a conversion factor such as 462. The frequency multiplier circuit 1935 is connected to a multiplier 1936, which multiplies its inputs to generate an IF transmission signal 1941. The IF transmit signal 1941 is connected to a spread spectrum band pass filter 1937 and a narrow band pass filter 1938. The spread spectrum band pass filter 1937 is a wideband filter, while the narrow band pass filter 1938 operates over a relatively narrow band. Band pass filters 1937 and 1938 specifically filter out CPM modulator spurs from the transmitter. The multiplexer 1939 selects between the output from the spread spectrum band pass filter 1937 and the output from the narrow band pass filter 1938, depending on the mode of the base station.

Multiplexer 1939 is connected to multiplier 1931. The clock divider circuit 1922 is connected to another clock divider circuit 1923, which divides its input by a factor of four, for example. The output of clock divider circuit 1923 is connected to frequency multiplier circuit 1930, which multiplies its input by a factor of (N + 400), where N is further described herein. However, it defines the frequency of the receive channel. A frequency multiplier circuit 1930 is connected to a multiplier 1931, which multiplies its inputs to generate an output signal 1942. Output signal 1942 is connected to diplexer 1910, which allows output signal 1942 to be transmitted through antenna 1901.

Signals received via antenna 1901 are passed through diplexer 1910 and provided to multiplier 1951. Clock divider circuit 1923 is connected to frequency multiplier circuit 1950, which multiplies its input by a coefficient of N, for example. A frequency multiplier circuit 1950 is connected to a multiplier 1951, which combines its inputs to generate a first IF signal 1944. The first IF signal 1944 is connected to a spread spectrum band pass filter and a narrow band pass filter 1953. The spread spectrum band pass filter 1952 is a wide band filter, while the narrow band pass filter 1953 operates over a relatively narrow band. Band pass filters 1952 and 1953 remove image noise and are anti-aliasing filters. Multiplexer 1954 selects between the output from spread spectrum band pass filter 1952 and the output from narrow band pass filter 1953.

Multiplexer 1954 is connected to multiplier 1960. The output from frequency multiplier circuit 1935 is also connected to multiplier 1960, which outputs the final IF signal 1946. The final IF signal 1946 is connected to the low pass filter 1961 and then to the A / D converter 1962. A / D converter 1962 is clocked at a rate determined by clock divider circuit 1926. The output of the A / D converter is provided to the ASIC 1920 for correlation and further processing. In particular, the received signal may be processed by the low-pass IF correlator shown in FIG. 18 and described above, in which case the A / D converter 1961 may be the same as the A / D converter 1811.

Typically, because of cost and equipment constraints, only one narrowband and one spread spectrum mode will be supported, but as many additional modes as needed by a single base station can be supported by providing similar additional hardware.

19B is a table showing selected frequencies and other parameters used in the dual mode base station of FIG. 19A. The table of FIG. 19B is divided according to spread spectrum and narrowband modes. The first three columns relate to different transmission rates using spread spectrum techniques, and the latter four columns relate to different transmission rates using narrowband techniques. The frequencies in each column are given in megahertz. The master oscillator frequency is designated f0 in FIG. 19B. M and M2 are programmable division ratios of clock division circuits 1926, 1927. The sample rate in FIG. 19B is applied to the A / D converter 1962 and the D / A converter 1933. The Fs / (IB + Fch) value represents the sampling rate. The final IF frequency and the second IF frequency are the center frequencies of the band pass filters. To the bottom of FIG. 19B are sample first L0 and N numbers for three different input frequencies, 1850 MHz, 1850.2 MHz, and 1930 MHz.

The frequencies and other parameters appearing in the table of FIG. 19B can be selected using a microprocessor or other software controller, where they are system timing information or as needed to adjust the time to switch the selected frequencies and other parameters as needed. You can query the clocks.

The user station 302 may not require the diplexer 1910 in air interface structures where the user station 302 does not need to transmit and receive simultaneously, the dual mode of FIGS. 19A-19B. It can be designed in a format similar to a base station. In addition, because the user station 302 transmits and receives on a frequency band opposite to the base station 304, the frequency multiplication circuits 1930 and 1950 can be exchanged.

Alternative embodiments

While preferred embodiments have been disclosed herein, many variations are possible that fall within the spirit and scope of the invention, and such variations may be read by those of ordinary skill in the art, reading the specification, drawings, and claims. Will be obvious.

For example, although some embodiments have been described generally with respect to spread spectrum communication, the present invention is not limited to spread spectrum communication techniques. In some narrowband applications, since code synchronization is not a problem (although synchronization in a TDD or TDMA structure is still required), no preamble will be needed.

In addition, although the control pulse preamble described with reference to FIGS. 10A-10E and 11A-11D facilitates operation in some circumstances, these embodiments may be implemented without the control pulse preamble. Various functions (eg, power control, antenna selection, etc.) performed by the control pulse preamble may be achieved or may not be required by analyzing other parts of the user transmission.

In alternative embodiments, one or more system control channels are used to facilitate other transactions with user stations 302 operating within a paging or effective area. In this embodiment, the control channel or channels are traffic information, system identification and ownership information, open time slot information, antenna scan and gain parameters at neighboring base stations to aid in handoff determination, and base station load state ( Provides base station or system information including base station loading status). The control channel or channels also specify user station operating parameters (e.g., timer counts, or variable thresholds for power control, channel switching, etc.), and incoming call alerting (e.g., Paging), provide timeframe or other synchronization, and allocate system resources (eg, time slots).

In the case of heavy traffic (ie, when a substantial portion of the time slots are in use), it may be advantageous to provide a fixed time slot to process paging transactions to minimize user station latency. In addition, the fixed paging time slot may eliminate the need to periodically send a general polling message from the base station in several time slots when it is open, thus polling messages and forward link traffic transmissions from the base station 304. Eliminate possible interference between the livers. The system information is preferably broadcast at maximum power or near power through a fixed paging time slot, allowing the user stations 302 in various ranges to hear and respond to the information.

This alternative embodiment may be further modified by supplying select diversity antennas to the user stations 302 and eliminating the user transmitting control pulse preamble. Rather than performing a reverse link transmission using a control pulse preamble followed by another forward link transmission, two preambles may be transmitted on the forward link. A comparison of such a structure with the embodiments described above is shown in FIG. 17. In FIG. 17, the air interface type is identified in the first column as before, with the trailing D representing the user station 302 having a select diversity antenna, and the trailing P having no diversity select antenna and having a control pulse. A user station 302 employing a preamble (or PCP) is shown. As shown in the FIG. 17 table, in an alternative embodiment employing a diversity antenna, the digital range may be improved or the number of time slots may be increased. These benefits arise because of the removal of the pulse control preamble, increasing the available time in each time frame that can be dedicated to extending the serviceable range or increasing the number of available time slots.

In another alternative embodiment, user transmission is performed before base station transmission. In this embodiment, the control pulse preamble may not be needed because the base station 304 obtains information about the mobile station power and channel quality by analyzing the user transmission. However, in such an embodiment, there is a long delay in the base station 304 issuing the coordination command to the user station 302 until the user station actually performs the coordination command in the next time frame, resulting in a control loop. To increase latency. Whether control loop latency adversely affects performance depends on system requirements.

In addition to the above modifications, the inventions disclosed herein may be invented and used in whole or in part in connection with the inventions disclosed in the following patents or co-pending applications, and as such, each of these patents and applications It is incorporated by reference as if fully set forth in the specification.

US Patent 5,016,255, entitled Asymmetric Spread Spectrum Correlator, issued under the names of inventors Robert C. Dixon and Jeffrey S. Vanderpool;

US Patent No. 5,022,047, entitled Spread Spectrum Correlator, issued under the names of inventors Robert C. Dixon and Jeffrey S. Vanderpool;

United States Patent No. 5,285,469, entitled Spread Spectrum Wireless Telephone System, issued by the inventor Jeffrey S. Vanderpool;

US Patent No. 5,291,516 entitled Dual Mode Transmitter and Receiver under the names Robert C. Dixon and Jeffrey S. Vanderpool;

US Patent No. 5,402,413, entitled Three Cell Wireless Communication System, entitled Robert C. Dixon;

US Patent Application Serial No. 08 / 161,187, entitled Method and Apparatus for Establishing Spread Spectrum Communication, filed December 3, 1993 in the name of inventor Robert C. Dixon;

US Patent Application Serial No. 08 / 146,491, entitled Despreading / Demodulating Direct Sequence Spread Spectrum Signals, filed November 1, 1993 in the names of inventors Robert A. Gold and Robert C. Dixon;

US Patent Application Serial No. 08 / 293,671, entitled Multi-Mode, Multi-Band Spread Spectrum Communication System, filed August 18, 1994, in the name of inventors Robert C. Dixon, Jeffrey S. Vanderpool, Douglas G. Smith;

US Patent Application Serial No. 08, filed August 1, 1994, in the name of inventors Gary B. Anderson, Ryan N. Jenson, Bryan K. Petch, Peter O. Peterson, and PCS Pocket Phone / Microcell Communication Over-Air Protocol. / 293,671;

US patent application Ser. No. 08 / 304,091, filed September 1, 1994, in the name of inventors Randy Durrant and Mark Burbach, entitled Coherent and Noncoherent CPM Correlation Method and Apparatus;

US Patent Application Serial No. 08 / 334,587, entitled Antenna Diversity Techniques, filed November 3, 1994, in the name of inventor Logan Scott; And

Spread Spectrum Correlation Using SAW Device, filed February 3, 1995, in the name of inventor Logan Scott; U.S. Patent Application Serial No. 08 / 383,518 to Lyon Lyon Inc. No. 201/081;

Also, variations in the transmitter 502 of the time frame 501 may be employed. For example, systems employing error correction on the forward link (ie, base station transmission) may interleave data destined for different user stations 302 over the entire burst of transmitter 502.

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Such variations and modifications and other variations and modifications to the communication techniques described herein will be apparent to those of ordinary skill in the art and are included within the scope and spirit of the present invention and within the scope of the appended claims. do.

Claims (186)

In the time division duplex communication method between a base station and a user station through a single frequency band, Transmitting a user message from a user station to a base station over a designated frequency band, Receiving the user message at the base station, Calculating, at the base station, a distance of the user station relative to the base station based on a time at which the base station receives the user message; and Using the base station message from the base station through the designated frequency band, the base station message comprising a timing adjustment instruction that causes the timing of a subsequent message from the user station to the base station over the designated frequency band to be advanced or retarded. Steps to send to your own country Time division duplex communication method comprising a. The method of claim 1, wherein at least one of the user message and the base station message is transmitted using a spread spectrum technique. 2. The time division duplex communication method according to claim 1, wherein the user station maintains a timing variable, and the timing adjustment command changes the timing variable to advance or delay the timing. 2. The time division duplex communication method according to claim 1, wherein the user station maintains a timing variable relative to a fixed reference, and wherein the timing adjustment command changes the timing variable to advance or delay the timing. The method of claim 1, wherein calculating the distance of the user station relative to the base station comprises calculating a propagation delay of the base station message reaching the user station and a propagation delay of the user message reaching the base station. Time division duplex communication method comprising a. 2. The time division method of claim 1, further comprising adjusting relative timing of subsequent messages from the user station by periodically transmitting a subsequent timing adjustment command from the base station to the user station over the designated frequency. Duplex communication method. The method of claim 1, wherein the user message is transmitted in response to a general polling message sent by the base station when attempting to establish communication with the base station. 2. The method of claim 1 wherein the user station is in communication setup with the base station and the user message includes a control pulse preamble. 9. The method of claim 8, wherein said control pulse preamble comprises a plurality of concatenated codes. 10. The method of claim 9, wherein the control pulse preamble comprises a kronecker product of a minimum peak sidelobe code and a Barker code. 2. The method of claim 1, wherein the user station is in communication setup with the base station and the user message comprises a traffic mode user-to-base message. A time division duplex communication method between a base station and a plurality of user stations over a single frequency band, wherein the base station sequentially communicates with the user stations in a communication setup state with the base station during a time frame, wherein the time frames have a plurality of identical durations. In the time division duplex communication method divided into time slots of Transmitting a first base station-user message from the base station to a user station over a designated frequency band during a designated time slot in a first time frame, Receiving a first user-base station message at the base station over the designated frequency band from the user station during the designated time slot in the first time frame; Transmitting from the base station to the user station over the designated frequency band a second base station-user message comprising a timing adjustment instruction during the designated time slot in a second time frame subsequent to the first time frame; and Receiving a second user-base station message advanced or delayed in response to the timing adjustment command from the user station during the designated time slot in the second time frame at the base station through the designated frequency band; Time division duplex communication method comprising a. 13. The method of claim 12, wherein after receiving the first user-base station message and before transmitting any subsequent base station-user message from the base station, the control pulse preamble is received from the second user station over the designated frequency band. And receiving at the base station. 15. The method of claim 13, wherein a third base station-user message from the base station to the third base station-user message includes a timing adjustment instruction over the designated frequency band during a second time slot immediately following the first time slot in the first time frame. Transmitting to the user station, and Receiving, at the base station via the designated frequency band, a third user-base station message advanced or delayed in response to the timing adjustment command from the second user station during the second time slot. Time division duplex communication method comprising a further. 15. The method of claim 14, wherein the control pulse preamble comprises a spread spectrum code. 15. The method of claim 14, wherein the control pulse preamble comprises a plurality of concatenated codes. 13. The method of claim 12, wherein at least one of the first user-base station message, the second user-base station message, the first base station-user message, and the second base station-user message is transmitted using a spread spectrum technique. Time division duplex communication method characterized in that. 13. The method of claim 12, wherein the user station maintains a timing variable, and wherein the timing adjustment command changes the timing variable to advance or delay the timing of the second user-base station message. . 13. The method of claim 12, wherein the user station maintains a timing variable relative to a fixed reference and the timing adjustment command changes the timing variable to advance or delay the timing of the second user-base station message. Time division duplex communication method. 13. The method of claim 12, further comprising calculating the distance of the user station relative to the base station. 21. The method of claim 20, wherein calculating the distance of the user station relative to the base station comprises propagating delay of the first base station-user message reaching the user station and the first user-base station message reaching the base station. Calculating a propagation delay of the time division duplex communication method. 21. The method of claim 20, further comprising receiving a control pulse preamble at the base station over the designated frequency band from the user station prior to transmitting the second user-base station message, wherein the user station is relative to the base station. The step of calculating a distance of the time division duplex comprises calculating a propagation delay of the first base station-user message reaching the user station and a propagation delay of the control pulse preamble arriving at the base station. Communication method. A system for performing time division duplex communication between a base station and multiple user stations over a single frequency band, Multiple time frames, and Multiple time slots in each of the time frames Including, Each of the time slots, A base station message interval in which a base station message can be transmitted by a base station through a predetermined frequency band to a user station in communication setting with the base station, and A user message interval in which a user message can be transmitted to the base station through the predetermined frequency band by a user station in a communication setup state with the base station. Including; And the base station periodically transmits a timing adjustment command to the user station in a communication setting state with the base station during the base station message period. 24. The system of claim 23 wherein at least one of the base station message and the user message is transmitted using spread spectrum techniques. 24. The time division duplex communication execution system according to claim 23, wherein said user station maintains a timing variable, and said timing adjustment command changes said timing variable to advance or delay the timing of said user station. 24. The time division duplex communication according to claim 23, wherein the user station maintains a timing variable relative to a fixed reference, and the timing adjustment command changes the timing variable to advance or delay the timing of the user station. Running system. 24. The time division duplex communication execution system according to claim 23, wherein the timing adjustment command is based on a distance calculation of the user station relative to the base station. 28. The system of claim 27, wherein the distance calculation includes calculation of a propagation delay of the base station message arriving at the user station and a propagation delay of the user message arriving at the base station. 28. The system of claim 27 wherein the user station is in communication setup with the base station and the user message comprises a traffic mode user-base station message. A system for executing time division duplex communication between a base station and a plurality of user stations over a single frequency band, wherein the base station sequentially communicates with the user stations in a communication setup with the base station. Multiple time frames with the same duration, and Multiple time slots in each of the time frames Including, Each of the time slots, During the time slot, a base station-user message may be sent by a base station to a user station in communication setup with the base station, or a general polling message indicating the availability of the time slot may be sent. Base station message interval in the portion, and Subsequent to the base station message interval in the time slot, a user-base station message may be sent to the base station by the user station in communication setup with the base station, or to a user station searching for communication setup with the base station. A user part in which a response message is transmitted to the base station, wherein the user part has the same frequency band as the base station message interval Including; And the base station periodically transmits a timing adjustment command to the user station in a communication setting state with the base station during the base station message period. 31. The system of claim 30, wherein the user portion comprises a preamble section in which a control pulse preamble can be transmitted by a second user station in communication setup with the base station. 32. The method of claim 31 wherein the second user station is in communication setup with the base station in a time slot immediately following the time slot in which the second user station transmitted the control pulse preamble. . A time division duplex communication method between a base station and a user station over a single frequency band, the base station sequentially communicating with the user stations in a communication setup state with the base station during a time frame, the time frame being a plurality of identical durations. In the time division duplex communication setup method divided into time slots, Transmitting a general polling message on a designated frequency band during a first base station interval of an available time slot in a first time frame, Receiving a response message from a user station over the designated frequency band during a user interval of the available time slot, Calculating, at the base station, a distance of the user station relative to the base station based on a time at which the base station receives the user message; and The base station message including a timing adjustment instruction that causes a timing of a subsequent message from the user station to the base station through the designated frequency band to be advanced or delayed during the second base station interval of the available time slot in a second time frame. Transmitting from the base station to the user station through a frequency band Time division duplex communication setting method comprising a. 34. The method of claim 33, wherein the base station and the user station communicate over the designated frequency band in the available time slots of subsequent time frames. 35. The method of claim 34, wherein the base station transmits a base station-user message to the user station in each of the subsequent time frames, and the user station transmits a user-base station message to the base station in each of the subsequent time frames. Time division duplex communication setting method. 36. The method of claim 35, wherein the base station-user message periodically includes new timing adjustment instructions. 36. The method of claim 35, wherein the user station transmits a control pulse preamble to the base station through the designated frequency band prior to each base station-user message. 38. The method of claim 37 wherein the control pulse preamble comprises a plurality of concatenated codes. 38. The method of claim 37, wherein the control pulse preamble comprises a Clinker product of a minimum peak sidelobe code and a Barker code. 34. The method of claim 33, wherein at least one of the general polling message, the response message, and the base station message is transmitted using a spread spectrum technique. 34. The method of claim 33, wherein the user station maintains a timing variable, and wherein the timing adjustment command changes the timing variable to advance or delay the timing. 34. The method of claim 33, wherein the user station maintains a timing variable relative to a fixed reference, and wherein the timing adjustment command changes the timing variable to advance or delay the timing. 34. The method of claim 33, wherein calculating the distance of the user station relative to the base station comprises calculating a propagation delay of the general polling message reaching the user station and a propagation delay of the response message reaching the base station. Time division duplex communication setting method comprising a. A time division duplex communication system in which a base station communicates with a plurality of user stations through a single frequency band, the time division duplex communication system comprising a plurality of periodic time frames, each time frame being divided into a plurality of base station time slots and corresponding user time slots. In a time-division duplex communication system, Transmitting a first user message from a user station to a base station over a frequency band in a user time slot, Receiving at the user station a base station message comprising a timing adjustment instruction from the base station over the constant frequency band; and Sending, from the user station to the base station, a second user message advanced or delayed at a relative timing relating to the start of the timing time slot in response to the timing adjustment command, over the constant frequency band in a user time slot; Time division duplex communication system comprising a. In the time division duplex communication frame structure between a base station and multiple user stations over a single frequency band, Multiple time frames, and Multiple time slots for each time frame Including, wherein each of the time slots, A base station transmission interval in which a base station can transmit a base station-user message to one of a plurality of user stations through a designated frequency band, and one of the user stations transmits a user-base station message through the designated frequency band to the base station; A user transmission section that can be sent to, And a first forward link transmission and a first reverse link transmission between the base station and the first user station are separated by an intervening forward or reverse link communication with a second user station. 46. The method of claim 45, wherein the forward link transmission and the first reverse link transmission separate the amount of time sufficient to propagate the first forward link transmission to a forward link destination and to propagate the first reverse link transmission to a reverse link destination. Time-division duplex communication frame structure, characterized in that. 47. The time division duplex communication frame structure of claim 46, wherein the forward link destination is the first user station and the reverse link destination is the base station. 48. The method of claim 47, further comprising a preamble interval preceding the first forward link transmission, wherein a control pulse preamble is received by the base station from the first user station. Time division duplex communication frame structure, characterized in that. 47. The time division duplex communication frame structure of claim 46, wherein the forward link destination is the base station and the reverse link destination is the first user station. 46. The time division duplex communication frame structure of claim 45, wherein the base station-user message periodically includes timing adjustment instructions for adjusting the relative timing of the user-base station message. In the time division duplex communication frame structure between a base station and multiple user stations over a single frequency band, Multiple time frames, and Multiple time slots for each time frame Including, wherein each of the time slots, A base station transmission interval in which a base station can transmit a base station-user message to one of a plurality of user stations through a designated frequency band, and one of the user stations transmits a user-base station message through the designated frequency band to the base station; A user transmission section that can be sent to, The duplex communication between the base station and the first user station is performed in the designated base station section and the designated user section, wherein the designated base station section and the designated user section are separated by at least one intervening base station section or user section. Rex communication frame structure. 53. The method of claim 51 wherein the base station segment and the designated user segment comprise a duplex pair, wherein time separation between the base station segment and the designated user segment is sufficient to propagate a first message over the forward link of the duplex pair. And sufficient to propagate a second message on the forward link of said duplex pair. 52. The time division duplex communication frame structure of claim 51, wherein the base station-user message periodically includes timing adjustment instructions for adjusting the relative timing of the user-base station message. A time division duplex communication method between a base station and a plurality of user stations over a single frequency band, wherein the base station communicates with the user stations in a communication setup state with the base station during a time frame, the time frame being a plurality of times having the same duration. In the time division duplex communication method divided into slots, Transmitting the first base station message from the base station to the first user station over the designated frequency band in the first time period of the time frame, Receiving the base station message at the first user station, Transmitting a first user message from a second user station to the base station over the designated frequency band, Receiving the first user message at the base station in a second time period of the time frame, Transmitting a second base station message from the base station through the designated frequency band in a third time period of the time frame; Transmitting a second user message from the first user station to the base station over the designated frequency band, and Receiving the second user message at the base station in a fourth time period of the time frame Time division duplex communication method comprising a. 55. The method of claim 54, wherein the time between transmitting the first base station message and receiving the second user message is sufficient to propagate the first base station message from the base station to the first user station. Time division duplex communication method, characterized in that it is sufficient to propagate a second user message from the first user station to the base station. 55. The method of claim 54, wherein at least one of the first user message, the second user message, the first base station message, and the second base station message is transmitted using a spread spectrum technique. . 55. The method of claim 54, further comprising: calculating, at the base station, a distance of the user station relative to the base station based on the time at which the base station receives the second user message; Using the first base station message from the base station through the designated frequency band, wherein the third base station message comprises a timing adjustment instruction that causes a timing adjustment instruction to advance or delay a subsequent message from the first user station to the base station over the designated frequency band. Steps to send to your own country Time division duplex communication method further comprising. 55. The method of claim 54, further comprising transmitting a control pulse preamble from the first user station to the base station over the designated frequency band prior to transmitting the first base station message to the first user station. Time division duplex communication method characterized in that. A time division duplex communication method between a base station and a plurality of user stations over a single frequency band during a time frame, wherein the time frame is divided into a plurality of time slots having the same duration. Transmitting a first base station-user message from the base station to the first user station during the first time slot; Receiving at the base station a first user-base station message from a second user station during the first time slot; Receiving, at the base station, a control pulse preamble from a third user station following the first user-base station message; Transmitting a second base station-user message from the base station to the third user station during a second time slot, and Receiving a second user-base station message from the first user station at the base station during the second time slot. Time division duplex communication method comprising a. 60. The method of claim 59, further comprising, after the second user-base station message, receiving a second control pulse preamble at the base station from a fourth user station. 60. The method of claim 59, further comprising calculating, at the base station, a distance of the third user station relative to the base station based on a time at which the base station receives the control pulse preamble. Message is characterized in that a subsequent message from the third user station to the base station is advanced or delayed in an associated timing. 60. The method of claim 59, further comprising: calculating, at the base station, a distance of the first user station relative to the base station based on a time at which the base station receives the second user-base station message; Transmitting a third base station-user message from the base station to the first user station in a subsequent time frame, the third base station-user message comprising a timing adjustment instruction for advancing or delaying the timing of a subsequent message from the first user station to the base station; Time division duplex communication method further comprising. In an interleaved time division duplex communication method between a base station and multiple user stations through a single frequency band, Receiving at the base station a control pulse preamble from a first user station over a designated frequency band, Transmitting a first base station-user message from the base station to the first user station over the designated frequency band, and Sufficient duration for receiving a first user-base station message from the second user station at the base station, sending a second base station-user message from the base station, and receiving a second control pulse preamble from the third user station at the base station After a time interval of, receiving a second user-base station message from the first user station at the base station over the designated frequency band Interleaved time division duplex communication method comprising a. 66. The method of claim 63 wherein the first base station-user message includes a timing adjustment command. 21. The interleaved time division duplex communication method according to claim 20, wherein in response to the timing adjustment command, a subsequent message transmitted from the first user station is advanced or delayed by an amount of time determined by the timing adjustment command. 64. The method of claim 63 wherein at least one of the first base station-user message and the second user-base station message is coded using spread spectrum techniques. In an interleaved time division duplex frame structure in which a base station communicates with multiple user stations through a single frequency band, Multiple time frames, and Multiple time slots in each of the time frames Including, Each of the time slots, A base station message interval in which a base station-user message can be transmitted by a base station over a predetermined frequency band to a first user station in communication setup with the base station, and A user message interval in which a user-base station message can be received at the base station via the predetermined frequency band from a second user station in communication setup with the base station, and A control pulse preamble may be received over the predetermined frequency band from a third user station in communication setup with the base station, and the base station may respond to the third base station in a subsequent time slot. Interleaved time division duplex frame structure comprising a. 68. The interleaved time division duplex frame structure according to claim 67, wherein the base station-user message includes a timing adjustment command. 69. The interleaved time division duplex frame structure according to claim 68, wherein, in response to the timing adjustment command, a subsequent message transmitted from the first user station is advanced or delayed by an amount of time determined by the timing adjustment command. 68. The interleaved time division duplex frame structure of claim 67, wherein at least one of the base station-user message and the user-base station message is coded using spread spectrum techniques. A system for performing time division duplex communication between a base station and multiple user stations over a single frequency band, Multiple time frames with the same duration, and Multiple time slots in each of the time frames Including, Each of the time slots, A base station-user message may be sent by the base station to the first user station during the time slot in communication setup with the base station, or a general polling message indicating the availability of the time slot may be sent by the base station. Base station interval, A user-base station message can be received at the base station from a second user station in communication setup with the base station, or a response message can be received at the base station from a third user station searching for communication setup with the base station. User segments, and A control pulse preamble may be received from a fourth user station in communication setup with the base station, and the base station may respond to the fourth base station in a subsequent time slot. Time division duplex communication execution system comprising a. 72. The system of claim 71 wherein the base station segment occupies an initial portion of a time slot and the user segment occupies a second portion of the time slot. 72. The system of claim 71 wherein the base station-user message includes timing adjustment instructions directed to the first user station. 74. The time division duplex communication execution system according to claim 73, wherein, in response to the timing adjustment command, a subsequent message sent from the first user station is advanced or delayed by an amount of time determined by the timing adjustment command. 72. The system of claim 71 wherein at least one of the base station-user message and the user-base station message is coded using spread spectrum techniques. 72. The system of claim 71 wherein in response to receiving the response message from the third user at the base station, the base station sends a timing adjustment command to the third user station. A time division duplex communication system between a base station and a plurality of user stations over a single frequency band, wherein the base station communicates with the user stations in communication setup with the base station during a time frame, the time frame being a plurality of times having the same duration. In a time division duplex communication system divided into slots, Receiving, at a first user station, a first base station message from a base station to the first user station over a designated frequency band in a first time period of a time frame, Waiting for the base station to receive a first user message from the second user station to the base station over the designated frequency band in a second time period of the time frame; Waiting for the base station to transmit a second base station message from the base station over the designated frequency band in a third time period of the time frame, and Transmitting from the first user station to the base station through the designated frequency band in a fourth time period of the time frame Time division duplex communication method comprising a. In a communication method between a base station and multiple user stations, Transmitting, from the base station to the user station, a plurality of base station-user messages corresponding to different base station time slots over a designated frequency band during the initial portion of the time frame, Receiving, at the base station, a plurality of user-base station messages from the user stations corresponding to different user time slots over the designated frequency band during the latter part of the time frame, Transmitting from the base station to at least one of the user stations a timing adjustment command over the designated frequency band during a subsequent time frame. Including, At least one subsequent user-base station message from the user station is advanced or delayed by an amount of time determined by the timing adjustment command. 79. The method of claim 78, wherein at least one of the base station-user message and the user-base station message is transmitted using a spread spectrum technique. 79. The method of claim 78, further comprising: transmitting from the base station a signal identifying an available user time slot, Receiving a response message over the designated frequency band from a user station searching for a communication setup with the base station during the available user time slot, Transmitting a second timing adjustment command from the base station to the user station searching for a communication setting with the base station through the designated frequency band; Include more, At least one subsequent user-base station message from the user station searching for a communication setting with the base station is advanced or delayed by an amount of time determined by the second timing adjustment command. . 81. The method of claim 80, wherein said response message is sent from said user station searching for communication settings with said base station in said available user time slot after a predetermined delay period. 81. The method of claim 80, wherein the response message is transmitted using spread spectrum techniques. 81. The method of claim 80 wherein the length of the response message is such that it is fully received by the base station prior to commencement of a second time slot immediately following the available user time slot. 79. The method of claim 78, wherein each user time slot is separated by a short guard band from a subsequent user time slot. 85. The method of claim 84, wherein the short guard band has a duration less than a full round trip propagation delay associated with a radius of a cell in which the base station is located. In a communication system using time division multiplexing, in a communication setting method between a base station and a user station, User stations that have already been established to communicate with the base station a plurality of base station-user messages, each corresponding to a different base station time slot, during the initial portion of the time slot including at least one of the plurality of base station time slots used for communication. Transmitting through a designated frequency band as Transmitting a response message over the designated frequency band from a user station searching for a communication setup with the base station during a user time slot paired with the available base station time slot in the user portion of the time frame; Receiving the response message at the base station, Calculating a propagation delay at the base station based on the relative time of receiving the response message, and deriving a timing adjustment command accordingly; Transmitting a timing adjustment command from the base station to the user station over the designated frequency band during a subsequent time frame, and In response to the timing adjustment command, advancing or delaying the relative timing of a subsequent user-base station message from the user station to the base station by the timing adjustment command. Communication setting method between the base station and the user station comprising a. 87. The method of claim 86, wherein the response message is sent from the user station in the user time slot after a predetermined delay period. 87. The method of claim 86, wherein one or more of the base station-user message and the user-base station message are transmitted using spread spectrum techniques. 87. The method of claim 86, wherein the response message is transmitted using spread spectrum techniques. 87. The method of claim 86 wherein the length of the response message is such that it is fully received by the base station prior to the commencement of the immediately following user time slot. A plurality of time frames of equal duration, each including a base station transmitter, a user guard, and a common guard located between the base station guard and the user guard, A plurality of base station time slots in the base station transmitter, wherein the base station can transmit a base station-user message to any one of a plurality of user stations during each base station time slot, and The corresponding one of the user stations during each user time slot is a plurality of user time slots separated by short guard bands at the user transmitter, capable of transmitting a user-base station message to the base station. Including, And the base station commands the relative timing of each user-base station message as a forward or delay time key in response to a propagation delay time calculated to at least one of the user stations. 92. The communication system according to claim 91, wherein a new user station searching for communication setup with the base station sends a response message to the base station during the joint protection. 93. The method of claim 92, wherein the base station calculates a new user station propagation delay for the new user station based on the time of receiving the response message, and receives a timing adjustment command during an available base station time slot of the base station time slots. A communication system characterized by transmitting to a new user station. 93. The communication system of claim 92, wherein the length of the response message is such that it is completely received by the base station before the common protection unit ends. 92. The communication system of claim 91, wherein a new user station searching for communication setup with the base station sends a response message to the base station during an available user time slot of one of the user time slots. 95. The method of claim 95, wherein the base station calculates a new user station propagation delay for the new user station based on the time of receiving the response message, wherein the base station timeslots correspond to the one available user time slot. And transmitting a timing adjustment command to the new user station during one base station time slot. 95. The communications system of claim 95, wherein the length of the response message is such that it is fully received by the base station prior to the commencement of the immediately following user time slot. 97. The communication system of claim 95, wherein the available user time slot is a first user time slot. 92. The communication system of claim 91, wherein one or more of the base station-user message and the user-base station message are transmitted using spread spectrum techniques. 92. The communication system of claim 91, wherein the shortened guard band has a duration less than a full round trip propagation delay related to the radius of the cell in which the base station is located. A method of performing time division multiplexed communication between a base station and multiple user stations over a single frequency band, Transmitting, over a designated frequency band, a base station burst comprising a plurality of time periods corresponding to base station time slots during a base station portion of the time frame—a base station-user message or a general polling message is transmitted in each of the base station time slots, The base station-user message is already sent in base station time slots for establishing communication with user stations, and the general polling message is sent in base station time slots used for communication; During the user portion of the time frame, a user-base station message already used for establishing communication with the base station and a response message that a new user station attempts to establish communication with the base station in user time slots over the designated frequency band. Receiving, and Periodically transmitting a timing adjustment command from the base station to at least one of the user stations over the designated frequency band, wherein a subsequent user-base station message from the user station is advanced by the amount of time determined by the timing adjustment command. Or delayed Time division multiplex communication execution method comprising a. 26. The time division method of claim 25, further comprising transmitting an initial timing adjustment command from the base station to at least one of the user stations attempting to establish communication with the base station through the designated frequency band. How to run multiplex communication. 102. The method of claim 101 wherein the base station time slots are interleaved. 102. The method of claim 101 wherein the base station time slots are noninterleaved. In a time division multiplex communication system between a base station and multiple user stations over a single frequency band, Multiple timeframes with the same duration, A base station transmitter in each of the time frames, In the base station transmitter, a base station-user message may be sent by a base station to a user station in communication setup with the base station, or a general polling message indicating availability of the time slot may be sent by the base station. Multiple base station time slots, A user transmitter in each of the time frames, distinct from the base station transmitter, and Each user time slot corresponds to any one of the base station time slots, and a user-base station message can be sent to the base station by the user station in communication setup with the base station, or a communication setup with the base station is established. A response message may be transmitted to the base station by the searching user station, and a plurality of user time slots in the user transmission unit having the same frequency band as the base station message interval. Including; And the base station periodically transmits a timing adjustment command to the user station in communication setting with the base station during the base station time slot. 107. The time division of claim 105, wherein the base station transmits an initial timing adjustment signal to at least one of the user stations attempting to establish communication with the base station in response to receiving a response message from the user station. Multiplexed Communication System. 107. The time division multiplex communication system of claim 105, wherein the base station time slots are interleaved. 107. The time division multiplexed communication system of claim 105, wherein the base station time slots are noninterleaved. In a communication method between a base station and multiple user stations, Transmitting a base station burst comprising a plurality of base station-user messages from a base station to user stations over a designated frequency band during the base station portion of the time frame, Receiving, at the base station, a plurality of user-base station messages from the user stations over the designated frequency band during the user portion of the time frame, each corresponding to a different user time slot; Transmitting a timing adjustment command from the base station to at least one of the user stations during a subsequent time frame, wherein a subsequent user-base station message from the user station is determined by the timing adjustment command. Advanced or delayed by Communication method between a base station and a plurality of user stations comprising a. 109. The method of claim 109, wherein the base station-user message is interleaved. 117. The apparatus of claim 110, wherein the base station burst comprises a plurality of blocks, each of the blocks comprising a plurality of sub-messages, each of the base station-user messages being at least one of the sub-messages from the plurality of blocks. Communication method between a base station and a plurality of user stations comprising a. 117. The method of claim 111, wherein each base station-user message includes exactly one sub-message from each of the blocks. 118. The method of claim 111, wherein at least one of the base station-users in each of the blocks is preceded by a preamble. 116. The method of claim 113, wherein all of the sub-messages in each of the blocks are preceded by a preamble. 116. The method of claim 113, wherein the preamble comprises a spread spectrum code. 118. The method of claim 110, wherein the user stations use forward error correction. 118. The method of claim 116, wherein the forward error correction comprises a Reed-Solomon coding technique. In a time division multiplex communication system between a base station and multiple user stations over a single frequency band, Multiple timeframes with the same duration, A base station transmitter in each of the time frames, including a plurality of transmission time slots, A plurality of sub-messages in each of the transmission time slots, wherein one or more sub-messages from the plurality of transmission time slots are transmitted by the base station to the same user station in communication setup with the base station; and A user transmitter in each of the time frames, including a plurality of user time slots for receiving user-base station messages from user stations in communication setup with the base station; Including; And the base station periodically transmits a timing adjustment command to the user station in a communication setting state with the base station during the base station transmission unit. 118. The time division multiplex communication system according to claim 118, wherein the user station receiving the timing adjustment command advances or delays the timing by an amount determined by the timing adjustment command. 118. The time division multiplex communication system of claim 118, wherein exactly one sub message from each of said transmission time slots is transmitted to a same user station. 118. The time division multiplex communication system of claim 118, wherein at least one of the sub-messages in each of the transmission time slots is preceded by a preamble. 121. The time division multiplex communication system of claim 121, wherein a preamble is preceded by all the sub-messages in each of the transmission time slots. 121. The time division multiplexed communication system of claim 121, wherein the preamble comprises a spread spectrum code. 121. The time division multiplexed communication system of claim 121, wherein the user stations use forward error correction. 121. The time division multiplexed communication system of claim 121, wherein said forward error correction comprises a Reed-Solomon coding technique. 121. The time division multiplex communication system of claim 121, wherein the user station searching for communication settings with the base station transmits a shortened message in an available user time slot of the user time slots. 126. The time division multiplex communication system according to claim 126, wherein the base station transmits an initial timing adjustment command to the user station searching for a communication setting in response to receiving the shortened message. 118. The time division multiplexed communication system of claim 118, wherein the user time slots are separated by a short guard band. In the duplex communication method between a base station and a user station through a plurality of frequency bands, Transmitting a control pulse preamble over a first frequency band from a user station, Receiving the control pulse preamble at a base station during a first preamble period; Transmitting a base station-user message from the base station to the user station over a second frequency band during a base station message interval; Receiving the base station-user message at the user station; Transmitting a user-base station message from the user station on the first frequency band, and Receiving the user-base station message at the base station during a user message interval Duplex communication method comprising a. 129. The method of claim 129, further comprising transmitting a plurality of preamble bursts through the second frequency band from the base station to the user station before transmitting the control pulse preamble. 133. The method of claim 130, wherein the number of preamble bursts is three. 131. The method of claim 130, wherein the number of preamble bursts is equal to the number of antennas used in the base station, The method, Measuring at the user station the relative received signal quality of the preamble burst; Transmitting the indication of the relative received signal quality from the user station as part of the user-base station message, and Selecting at the base station one or more of the antennas for subsequent messages to the user station in response to the relative received signal quality Duplex communication method further comprising. 129. The method of claim 129 wherein the base station-user message includes a timing adjustment command sent to the user station. 137. The duplex communication method according to claim 133, in response to the timing adjustment command, a subsequent message transmitted from the user station is advanced or delayed by an amount of time determined by the timing adjustment command. 129. The method of claim 129 wherein at least one of the base station-user message and the user-base station message is coded using spread spectrum techniques. 129. The method of claim 129 wherein the base station can be transmitted in spread spectrum or narrowband mode. 129. The method of claim 129 wherein the control pulse preamble comprises a spread spectrum code. 129. The method of claim 129 wherein the control pulse preamble comprises a plurality of concatenated codes. 138. The method of claim 138, wherein the control pulse preamble comprises a Clinker product of a minimum peak sidelobe code and a Barker code. In the communication method between a base station and a plurality of user stations over a plurality of frequency bands, Transmitting a first base station-user message from the base station to the first user station over the base station transmission frequency band during the first time slot; Receiving the first base station-user message at the first user station; Transmitting a control pulse preamble from a second user station to the base station over a user transmission frequency band, Receiving the control pulse preamble at the base station during the first time slot, Transmitting a second base station-user message from the base station to the second user station over the base station transmission frequency band during a second time slot; Receiving the second base station-user message at the second user station; Transmitting a user-base station message from the first user station to the base station via the user transmission frequency band; and Receiving the user-base station message at the base station during the second time slot Communication method comprising a. 141. The method of claim 140, further comprising: transmitting a second user-base station message from the second user station to the base station over the user transmission frequency band; Receiving the second user-base station message at the base station during the third time slot Communication method characterized in that it further comprises. 145. The method of claim 141, further comprising: transmitting a second control pulse preamble from a third user station to the base station via the user transmission frequency band, Receiving the second control pulse preamble at the base station during the second time slot; Transmitting a third base station-user message from the base station to the third user station over the base station transmission frequency band during the third time slot; Receiving the third base station-user message at the third user station; Transmitting a third user-base station message from the third user station to the base station over the user transmission frequency band, and Receiving the third user-base station message at the base station during the fourth time slot Communication method comprising a. 141. The method of claim 140, wherein the second base station-user message includes a timing adjustment command. 143. The communication method according to claim 143, wherein in response to the timing adjustment command, a subsequent message sent from the second user station to the base station is advanced or delayed by an amount of time determined by the timing adjustment command. 141. The method of claim 140, wherein at least one of the first base station-user message, the second base station-user message, and the user-base station message is coded using spread spectrum techniques. 141. The method of claim 140, further comprising transmitting a plurality of preamble bursts through the base station transmission frequency band from the base station to the first user station before transmitting the control pulse preamble. 141. The method of claim 140, wherein the second time slot immediately follows the first time slot. 144. The method of claim 140, wherein the relative starting reference point for each time slot that includes the first time slot and the second time slot is offset in time with respect to the user transmission frequency band with respect to the base station transmission frequency band. Communication method. 148. The apparatus of claim 148, wherein the offset is a duration sufficient for the first base station-user message to propagate from the base station to the first user station, and the user-base station message to propagate from the first user station to the base station. The communication method characterized by the above-mentioned. 141. The method of claim 140, wherein the base station can be transmitted in spread spectrum or narrowband mode. In the communication frame structure between a base station and a plurality of user stations over a plurality of frequency bands, Multiple time frames with the same duration, and Multiple time slots in each of the time frames Including, Each of the time slots, A base station-user message may be sent by a base station over a first frequency band during the time slot to a first user station in a communication setup with the base station, or a general polling message indicating the availability of the time slot is received. A base station section that can be transmitted through one frequency band, A user-base station message may be received at the base station via a second frequency band from a second user station in communication setup with the base station, or a response message may be received from a third user station searching for communication setup with the base station. A user interval that can be received at the base station through the second frequency band, and A control pulse preamble may be received over the second frequency band from a fourth user station in communication setup with the base station, and the base station may respond to the fourth base station in a subsequent time slot. Communication frame structure comprising a. 151. The communication frame structure of claim 151, wherein said base station-user message includes a timing adjustment instruction sent to said first user station. 151. The communication frame structure of claim 151, wherein at least one of the base station-user message and the user-base station message is coded using spread spectrum techniques. 151. The communication frame structure according to claim 151, wherein the base station transmits a timing adjustment command to the third user station in response to receiving the response message from the third user station at the base station. 151. The communication frame structure of claim 151, wherein the user interval is offset from the base station interval by a predetermined amount of time less than the duration of all time slots. 151. The communication frame structure of claim 151, wherein the user interval and the base station interval substantially overlap. 151. The communication frame structure of claim 151, wherein said base station can be transmitted in spread spectrum or narrowband mode. In the interleaved broadcast interface frame structure for performing time division multiplex communication between a base station and a plurality of user stations over a plurality of frequency bands, During each time frame, according to a predetermined protocol, a plurality of time frames in which a base station can be transmitted on a first designated frequency band, and user stations can be transmitted on a second designated frequency band, and A plurality of time slots in each of the time frames, each having a base station section corresponding to the first designated frequency band and a user station section corresponding to the second designated frequency band. Including; The base station unit may be a base station message interval for transmitting a first base station-user message to the first base station in response to receiving the first control pulse preamble in a time slot immediately preceding the base station and the base station at least one preamble burst And a base station preamble interval capable of transmitting to a second user station, wherein the second user station may respond to the at least one preamble burst in a subsequent time slot, The user station unit may send a user message base station in response to receiving a second base station-user message in a time slot immediately preceded by a third user station and a fourth user station transmits a control pulse preamble to the base station. A control pulse preamble interval that can be transmitted, wherein the base station is capable of responding to the control pulse preamble in the subsequent time slot. Interleaved broadcast interface frame structure, characterized in that. 158. The interleaved broadcast interface frame structure as claimed in claim 158, wherein the user station is offset from the base station by a predetermined amount of time less than the duration of all time slots. 158. The interleaved broadcast interface frame structure as recited in claim 158, wherein the base station-user message includes a timing adjustment instruction transmitted to the first user station. 158. The interleaved broadcast interface frame structure of claim 158, wherein at least one of the base station-user message and the user-base station message is coded using spread spectrum techniques. 158. The interleaved broadcast interface frame structure according to claim 158, wherein the base station can be transmitted in spread spectrum or narrow band mode. 158. The interleaved broadcast interface frame structure as recited in claim 158, wherein the control pulse preambles are concatenated. In an interleaved frequency division duplex frame structure for communication between a base station and a plurality of user stations, Multiple time frames, and Each of the time slots comprises a base station portion and a user station portion, the duplex pair consisting of a first base station portion in a first time slot and a first user station in a second time slot subsequent to the first time slot Multiple time slots in each frame Including; A base station transmits a base station-user message on the first designated frequency band during the first base station portion, the base station receives a user-base station message on the second designated frequency band from the user station during the first user station portion, During each time slot, the user station section is offset from the base station section by a predetermined amount of time. An interleaved frequency division duplex frame structure, characterized in that. 175. The system of claim 164, wherein the predetermined amount of time is passed from the first user station such that the base station-user message propagates from the base station to the first user station, and the user-base station message is received at the first user station part. Interleaved frequency division duplex frame structure, characterized in that it is of sufficient duration to propagate to the base station. 164. The interleaved frequency division duplex frame structure according to claim 164, wherein the base station-user message includes a timing adjustment instruction transmitted to the user station. 175. The interleaved frequency division duplex frame structure of claim 164, wherein at least one of the base station-user message and the user-base station message is coded using spread spectrum techniques. 175. The interleaved frequency division duplex frame structure according to claim 164, wherein the base station can be transmitted in spread spectrum or narrow band mode. 164. The method of claim 164, further comprising a preamble interval in each time slot for receiving a control pulse preamble on the second designated frequency band from a user station in communication setup before the base station replaces traffic messages. An interleaved frequency division duplex frame structure. 171. The apparatus of claim 169, wherein the base station transmits a plurality of preambles to the user station in a communication setup state over the first designated frequency band before receiving the control pulse preamble, one for each preamble burst period. The interleaved frequency division duplex frame structure, characterized in that it further comprises a plurality of preamble burst intervals. 172. The interleaved frequency division duplex frame structure of claim 170, wherein the number of the preamble burst intervals is three. 172. The method of claim 170, wherein the number of the preamble burst intervals is equal to the number of antennas used in the base station, and the user station measures the relative received signal quality of the preamble burst to display an indication of the relative received signal quality. An interleaved frequency division duplex frame structure, characterized in that it is transmitted to the base station as part of a base station message. 172. The interleaved frequency division duplex frame structure of claim 172, wherein the base station selects one or more of the antennas for subsequent messages to the user station in response to the relative received signal quality. In the duplex communication frame structure between a base station and a plurality of user stations over a plurality of frequency bands, Multiple time frames, and Multiple time slots for each time frame Including; Each of the time slots includes a base station transmission interval and a base station for transmitting a base station-user message to a first user station among a plurality of user stations in a communication setup state with the base station through a first designated frequency band. A user transmission interval capable of receiving a base station message from a second user station of the user stations via a second designated frequency band, The start of the user transmission interval in each time slot is offset by a predetermined amount of time relative to the start of the base station transmission interval. A duplex communication frame structure, characterized in that. 176. The method of claim 174, wherein the base station-user message to the first user station comprises a duplex pair of forward link transmissions, and reverse link transmissions from the first user station to the base station immediately follow the forward link transmissions. A duplex communication frame structure, which is generated in a time slot. 175. The method of claim 175, wherein the forward link transmission and the reverse link transmission are such that the forward link transmission is propagated to the first user station without simultaneous reception and transmission by the first user station, and the reverse link transmission is performed by the base station. A duplex communication frame structure, characterized in that separated by a sufficient amount of time to propagate. 175. The method of claim 175, further comprising a preamble interval preceding the first forward link transmission, wherein a control pulse preamble is received by the base station from the first user station over the second designated frequency band. Duplex communication frame structure. 175. The duplex communication frame structure of claim 175, wherein said base station-user message includes timing adjustment instructions for adjusting the relative timing of said reverse link transmissions. In the communication method between a base station and a plurality of user stations over a plurality of frequency bands, Transmitting a first base station-user message from a base station to a first user station over a base station transmission frequency band during a first time period, Receiving the first base station-user message at the first user station; Transmitting a control pulse preamble from a second user station to the base station over a user transmission frequency band, Receiving the control pulse preamble at the base station during a second time period, Transmitting a second base station-user message from the base station to the second user station over the base station transmission frequency band during a third time period; Receiving the second base station-user message at the second user station; Transmitting a user-base station message from the first user station to the base station via the user transmission frequency band; and Receiving the user-base station message at the base station during a fourth time period Communication method comprising a. 179. The method of claim 179, wherein the first time period and the second time period comprise a first time slot, and the third time period and the fourth time period comprise a second time slot. 182. The method of claim 180, wherein the second time slot immediately follows the first time slot. 182. The method of claim 180, wherein the third time period and the fourth time period overlap at least partially. 179. The method of claim 179, further comprising: transmitting a second user-base station message from the second user station to the base station via the user transmission frequency; Receiving the second user-base station message at the base station during a fifth time period Communication method characterized in that it further comprises. 179. The method of claim 179, wherein the second base station-user message includes a timing adjustment command. 185. The communication method according to claim 184, wherein a subsequent message transmitted from the second user station to the base station according to the timing adjustment command is advanced or delayed by an amount of time determined by the timing adjustment command. In the duplex communication method between a base station and a user station through a plurality of frequency bands, Transmitting the control pulse preamble from the user station to the base station over the first frequency band, Receiving a base station-user message from the base station at the user station over a second frequency band, and Transmitting a user-base station message from the user station to the base station over the first frequency band Duplex communication method comprising a.