KR20010071268A - Signal decoding with or without second synchronization word in a mobile communication system - Google Patents

Abstract

The time division multiple access (TDMA) wireless communication system 100 provides signal decoding by the mobile station 130 with or without the second synchronization word 214. During subsequent time slots 202, 204, 206 including a current time slot 202 and a subsequent time slot 204, the wireless communication system includes at least one base station 102, 104 to transmit a radio signal. do. The wireless signal includes an indication indicating whether transmission of subsequent time slots is guaranteed. According to the invention, the system further comprises at least one mobile station to receive a radio signal.

Description

SIGNAL DECODING WITH OR WITHOUT SECOND SYNCHRONIZATION WORD IN A MOBILE COMMUNICATION SYSTEM}

In a time division multiple access (TDMA) wireless communication system, to transmit a radio signal, each transmitter of the system is assigned or assigned to a time slot. During this time slot, all other transmitters are stopped so that the designated receiver can reliably receive the radio signal. If the wireless communication system is a two-way mobile system such as a cellular radiotelephone, the radio carrier frequency of the first frequency band is divided into time slots and communicated from different mobile stations of the plurality of mobile stations to the base station to communicate from the base station to the multiple mobile stations. For this purpose, the radio carrier frequency of the second frequency band is divided into time slots. The base station communicates with a mobile station in a fixed area near the base station. The other adjacent base station communicates with mobile stations in the adjacent area.

During some time slots, the base station transmits control and timing information. For example, this information includes identification information of the mobile station for assigning the incoming call to the paging channel and synchronization or timing information on the synchronization or sync channel. The mobile station of the system receives the synchronization channel to synchronize the timing of the synchronization channel and the base station timing using the information of the synchronization channel. In general, each time slot also includes a known data pattern, allowing the mobile station to easily estimate the channel phase and amplitude used to decode the symbols sent to the slot.

It is known to improve the reception and decoding of symbols using the synchronization word at the beginning of the current time slot and the synchronization word at the end of the current slot and the beginning of the next slot. Due to fade or other interference in the channel, the current or first synchronization word cannot be reliably received. By storing the received signal sample comprising the second synchronization word, the stored signal sample can be decoded using either the first coded word or the second coded word, or both. This technique is described in US Pat. No. 5,353,250 to Dent et al. On August 2, 1994 and US Pat. No. 5,841,816 to 24 November 1998. Both of these patents are jointly assigned with this patent application and are incorporated herein by reference. For optimal performance, some mobile stations are currently used to receive second synchronization words.

In some mobile wireless systems, when no time slot is assigned, it is arranged to suspend or change the transmission of information including the synchronization word. If no time slot is assigned, no mobile station currently uses this time slot. The current time slot degrades the operation of a mobile station in which the phase, amplitude, or direction of transmission by the base station is present, which can change the subsequent time slot associated with the current time slot without using the present invention. However, it is desirable to avoid transmitting information by base stations in unassigned time slots, thereby reducing interference to peripheral area receivers. Eliminating other information and synchronization word transmissions during unassigned time slots reduces or eliminates cross-channel interference that improves all performance of the wireless system. This improvement risks performance degradation because the mobile station lacks the ability to use the second codeword.

For a mobile station that trusts reception of a second coded word for improved communication, if an unassigned time slot comes after the time slot assigned to the mobile station, the removal of the synchronization word or the timing, phase, or phase in the unassigned time slot. Characteristic changes, such as the direction of transmission, cause problems. The mobile station may not be able to successfully decode the channel or may spend inappropriate time looking for a second codeword. Thus, a need exists for a method and apparatus for removing transmission of some slots by a base station of a mobile wireless communication system without degrading the remaining slot performance.

The present invention relates generally to signal transmission / reception in mobile wireless communication systems. In particular, the present invention relates to signal decoding in a mobile wireless communication system provided for stopping transmission from a base station of a system for a selected time period.

1 is a block diagram of a wireless communication system;

2 is a diagram illustrating a communication format in the wireless mobile communication system of FIG. 1;

3 is a flow chart illustrating a method for operating a base station in the wireless communication system of FIG.

4 is a flow chart illustrating a method for operating a mobile station of a first form of the wireless communication system of FIG. And

5 is a flow chart illustrating a method for operating a mobile station of a second type of the wireless communication system of FIG.

Referring to the drawings, FIG. 1 illustrates a wireless communication system 100 that includes at least one base station 102, 104 and at least one mobile station 130. As shown in FIG. The wireless communication system 100 may be a two-way wireless communication system such as a cellular wireless telephone system, a personal digital communication system (PCS), a frequency common communication system, or the like. In the illustrated embodiment, the wireless communication system 100 is a cellular radiotelephone system that operates in accordance with provisional agreement IS-136 issued by the Telecommunications Industry Association / Electronic Industry Association (TIA / EIA).

In FIG. 1, the system 100 is shown with two base stations 102 and 104. In general, all base stations are made in a similar fashion, and the base station structure and operation are described in conjunction with the base station 102. The base stations of the system including base stations 102 and 104 are all connected together to form a network. The network is controlled by a mobile switching center (MSC) 106. The MSC 106 is connected to each of the base stations 102 and 104 by landline, telephone link or wireless link. The MSC 106 controls overall network operation, provides access to a public switched telephone network (PSTN), and controls the interaction of base stations, such as wireless communication handover between two base stations and the system 100. Provide a single mobile station.

Base station 102 is a typical example of base station structure and operation. Base station 102 includes a controller 110, a transmitter 112, a receiver 114, a memory 116, a clock 118, and an antenna 120. Controller 110 controls the overall operation of base station 102. Each base station communicates bidirectionally with one or more mobile stations in a fixed area near the base station. The area may be divided into sectors provided by the antenna or antenna unit 120.

Transmitter 112 uses antenna 120 to transmit a radio signal to a mobile station, such as mobile station 130, in a fixed area around base station 102. The transmitter 112 may include functions such as encoding, interleaving, and modulation. Receiver 114 converts the signal into digital data for use in base station 102 with a wireless signal received at antenna 120. The receiver may include functions such as filtering, demodulation and decoding. In order to operate the controller 110 and use other circuitry in the mobile station 102, the memory 116 stores data and instructions.

Clock 118 provides a time base for operating base station 102. In general, device operation in the system 100, including the base station, MSC 106, and mobile station, must be fully synchronized. Clock 118 is used to receive a synchronization signal from MSC 106 and then provide the synchronization signal to a mobile station, such as mobile station 130.

Those skilled in the art will appreciate that the base stations 102, 104 may include other functions and other circuits. These functions include a management call initiation function to the mobile station and a handover function for communicating with the mobile station from one base station to another.

Mobile station 130 is a typical example of a mobile station capable of operating in wireless communication system 100. The mobile station can be a radio capable of bidirectional communication with a remote base station, such as a cellular telephone, a PCS telephone, or a two-way radio. In the illustrated embodiment, the mobile station 130 is a cellular telephone capable of operating in accordance with IS-136. The mobile station 130 of the illustrated embodiment includes an antenna 132, a reception path 134, a transmission path 136, a controller 138, a memory 140, a user interference 142, a battery 144, a clock 146. And a speech synthesis device 148.

The receiving path 134 receives the radio signal detected by the antenna 132 and generates digital data for use in the mobile station 130. The reception path 134 includes an analog front end 150, a demodulator 152 and a decoder 154. Analog front end 150 includes a suitable filter and low noise amplifier for detecting and filtering wireless signals received at antenna 132. The analog front end 150 uses a circuit, such as a mixer, coupled with the speech synthesis device 148 to shift the frequency where the wireless signal is transmitted simultaneously at a lower frequency for easier processing at the mobile station 130. It may include more. The demodulator 152 processes the received sample signal by using a synchronization word or a known symbol pattern to determine the multipath propagation channel estimate, and then uses the channel estimate to generate soft-decision and cross-symbol interference that is supplemented by multipath. The signal sample for processing is processed. The soft-decision is then fed from the demodulator 152 to a decoder 154 that operates the error correction code to generate error-correction information to the controller 138.

The transmission path 136 converts the digital data generated by the controller 138 into a radio signal for transmission using the antenna 132. The transmission path 136 includes an encoder 160, a modulator 162 and a transmitter 164. Encoder 160 encodes the digital data provided by controller 138 into a format required for communication in the system 100 including interleaving. Encoded data is provided to a modulator 162, which uses the encoded data to modulate the carrier signal provided by the speech synthesis device 148. A modulated carrier is provided to the transmitter 164, which provides functions such as power amplification and filtering. Thereafter, an amplified carrier is applied to the antenna 132 for transmission to remote base stations such as base stations 102 and 104.

The controller 138 controls all the functions of the mobile station 130. Preferably, controller 138 is implemented as a microcontroller, digital signal processor or microprocessor or a combination thereof and operates in response to data and instructions stored in memory 140. User interface 142 allows control of a user's mobile station and typically includes a keypad, microphone, speaker, and indicator. Battery 144 provides power for operation at mobile station 130. The clock 146 provides timing to the circuitry of the mobile station 130. In particular, the clock 146 provides a timing signal where the controller 138 is used so that the mobile station 130 including the controller 138 can be synchronized with the rest of the communication system 100.

In the illustrated embodiment, the wireless communication system 100 is a time division multiple access (TDMA) wireless communication system. When the transmitter of the system 100 operates in the system 100, each mobile transmitter of the system 100 allocates or allocates a time slot for transmitting a radio signal. During this time slot, all other mobile transmitters using the same frequency in the same cell are stopped so that the designated receiver can reliably receive radio signals on the channel. Of course, at a single cell or at a different frequency, different mobile transmitters can freely use the same time slot.

One example of a TDMA wireless communication system is a cellular telephone system in accordance with interim standard IS-136. IS-136 typically defines a communication frame with six time slots assigned in pairs to form a full-rate channel. Therefore, the full-rate channel is actually a three-slot TDMA system. By combining slots on the uplink frequency and slots on the downlink frequency, two channels can be created for bidirectional communication between the base station and a particular mobile station.

2 illustrates a communication format in the wireless communication system of FIG. 2 is a portion of a communication frame 200 that includes three time slots, namely a first time slot 202, a second time slot 204, and a third time slot 206. Time slots 202, 204, and 206 are all sent to the base station of system 100 of FIG.

Each time slot includes a synchronization word. Therefore, the first time slot 202 includes the synchronization word 212, the second time slot 204 contains the synchronization word 214, and the third time slot 206 contains the synchronization word 216, respectively. . At a predetermined location near the beginning of each time slot, the sync word or sync word consists of a predetermined data pattern. To synchronize the timing and decode the transmission time slot, the receiving mobile station uses a synchronization word.

To receive to a single mobile station near the base station, each time slot and its associated synchronization word is assigned to the transmitting base station. However, in the current IS-136 system, all three time slots are always designated so that the designated mobile station can receive not only subsequent time slots but also other time slots, such as previously designated time slots. In IS-136, indicating transmission format time-inverse symmetry, the mobile station can demodulate the first sync word transmission information or the second sync word reception information. However, in more complex systems, in the absence of data to be transmitted, time slots may be omitted, reducing the interface to unspecified receivers, but deleting the second synchronization word at the designated receivers.

It is known that receiving and decoding symbols at the mobile station has been improved using the synchronization word of the current time slot and the subsequent synchronization word of the time slot. Such methods are described in US Pat. No. 5,335,250, issued August 2, 1994 to Dent et al., And US Pat. No. 5,841,816, issued 24 November 1998. In general, all such patents have been jointly assigned with this patent application and are incorporated herein by reference. Here, the decoding method or other suitable decoding method of such a reference is called a first decoding algorithm or technique. According to the embodiment disclosed herein, if the base station cannot guarantee the transmission of the synchronization word in the next time slot, the mobile station uses a second decoding algorithm or technique.

In accordance with the decoding and demodulation technique described in the reference, the mobile station receives an assigned or allocated time slot of a TDMA frame period. Using the first decoding algorithm, the mobile station is configured to know the known symbol transmitted near the beginning of the assigned time slot, called the first synchronization word, and near the beginning of the subsequent time slot, referred to herein as the second synchronization word. Decode the received signal for the transmitted, known symbol. The alternative method described above is that the base station transmits a predetermined first data symbol and an unknown data symbol. The synchronization word or other known data pattern forms a predetermined first data symbol. The specific data designated for a particular mobile station is an unknown data symbol. Unknown data symbols can encode voice data, control data, and the like. In some systems, the base station transmits a predetermined second data symbol, such as a second synchronization word, in a subsequent time slot.

In some systems, a known symbol at the beginning of a subsequent time slot, such as a second synchronization word, cannot be guaranteed to have been transmitted by the base station. For example, cross-channel interference can be reduced for receivers in the peripheral region. If a subsequent time slot is not assigned to the base station's mobile station, the base station can suspend transmission for an unassigned time slot containing a synchronization word, thereby reducing co-channel interference. As an alternative, the base station may use a directional antenna that simultaneously transmits time slots to one particular sector of the area provided by the base station. This sector is distinct from the sector with the mobile station currently assigned to the time slot. Therefore, because of the beam direction change, the second time slot cannot be received in interference with the preceding slot data.

Due to this possibility, the base station cannot guarantee the transmission of a predetermined second data symbol, such as a synchronization word of a subsequent time slot. In addition, even if the symbol is transmitted, if the base station completely changes the timing or phase or amplitude of a subsequent time slot for some specific reason, the second predetermined data symbol cannot be used. Since the mobile station uses the synchronization word to synchronize its timing and receive it to the base station, any change in these variables can destroy the synchronization, requiring the base station to resynchronize the mobile station.

Although, at the beginning of the next time slot, when a known symbol such as a synchronization word is not guaranteed to be transmitted by the base station, or when timing, phase, amplitude or directional continuity associated with the transmission of the current time slot is not guaranteed, The base station according to the invention provides a signal to the mobile station indicating that the synchronization word is unreliable. In the alternative described above, the base station transmits an indication when the transmission of the predetermined second data symbol is not guaranteed.

The mobile station decodes the signal transmitted from the base station using at least the predetermined first data symbol. If the signal sent by the base station indicates that the transmission of the predetermined second data symbol or second synchronization word is reliable, then the mobile station uses the predetermined first data symbol or the predetermined second data signal, or both. Decode the time slot received at the base station according to the integrated description of the "first" algorithm. Appropriate algorithms or other similar ones of the incorporated references may be used.

When the mobile station receives an indication that the predetermined second data symbol or second synchronization word is unreliable, the mobile station decodes the received signal in the selected time slot using the second decoding algorithm. The second decoding algorithm only requires known symbols sent in the selected time slot. It is disclosed in the above reference that, if the indication that the second synchronization word is unreliable, a change occurs by permanently setting the second synchronization word characteristic to the lowest characteristic value, the second decoding algorithm is one such variation. Another suitable decoding algorithm can be used to generate one guaranteed synchronization word.

Therefore, when an indication is sent, the mobile station decodes an unknown data symbol using the predetermined first data symbol, and when the indication is not transmitted, the unknown uses the predetermined first data symbol and the second data symbol. Decode the data symbols. The indication may be any of the appropriate data or signals contained in the control signal information sent by the base station to the mobile station. In one embodiment, an indication is sent while the call is being established or handed over. When bi-directional communication is initiated between the mobile station and the base station, a call setup occurs. Call initiation occurs when the mobile station indicates that the user is about to make a call outside, or when the base station signals to make an internal call on the paging channel. When the mobile station moves from the coverage area of the first base station to the coverage area of the second base station, a handover occurs. While all these occurrences occur, sufficient control information is exchanged between the mobile station and the base station.

In one embodiment, the base station sends the indication simultaneously to all mobile stations that are in the cover area or sectors of the cover area. By using a digital control channel or broadcast control channel (BCCH), also known as DCC, this can be achieved. The indication informs the mobile station that the base station uses an operating mode that cannot guarantee the availability of the second synchronization word. In response, all base stations in the sector or coverage area then use a second decoding algorithm.

In another embodiment, the mobile station provides an indication to the base station, which requires the second synchronization word to the base station to optimally decode time slot information from the base station. This is suitable for compatibility with mobile stations having the above requirements. According to this embodiment, the mobile station sends an indication, which indicates that the mobile station requires the transmission of a predetermined second data symbol. In response to the indication, even when there is no data transmitted in subsequent slots, the trusted base station according to the present invention transmits a predetermined second data symbol. The base station does not suspend transmission of the second synchronization word and does not change the transmission phase or amplification or any other necessary characteristic, but if there is no data to be transmitted, the transmission of data according to the second word may be omitted.

The indication for the mobile station may comprise a predetermined data pattern or an operation mode indication for the mobile station. The indication may be sent with control information provided by the mobile station to the base station.

Alternatively, an indication may be included in the reference information sent by the mobile station to the base station. For example, each mobile station may have a protocol version number sent to the base station when initiating communication between two mobile stations. The protocol version number cites a revision of the standard, such as IS-136, used by the mobile station. In response to the protocol version number or other similar indication, the base station may determine whether the mobile station expects the second coded word or operates reliably without the transmission of the second synchronization word. In addition, one of these two modes of operation can be set as a fault, with a non-default state selected according to the base station's appropriate decision. In addition, in another embodiment, the base station may determine the mode of operation by using an identifier such as the electronic serial number (ESN) of the mobile station transmitted by the mobile station during call setup. By comparing the values stored in the mobile station's ESN and the base station's memory or the mobile station's ESN and elsewhere on the communication network, the base station can retrieve the characteristics of the mobile station from a subscriber database including the operating modes provided to the mobile station. Therefore, after the base station determines the transmission requirement for the mobile station, it transmits a second predetermined data symbol in response to the transmission requirement for the mobile station.

3 is a flow chart illustrating a method for operating a base station in the wireless communication system 100 of FIG. The method begins at step 302. In step 304, the base station determines if the mobile station requires a second synchronization word. This includes a method of receiving signal information from a mobile station including an implied indication that the mobile station requires a second synchronization word, or receiving an identifier or other information from the mobile station and comparing the identifier with stored data to request transmission of the mobile station. It depends on the appropriate method, such as how to decide the matter. In the embodiment shown in Figure 1, the controller 110 of the base station 102 forms a means for determining the type of particular mobile station that is in wireless communication with the base station. For this purpose, controller 110 may operate with memory 116 or with other data processing devices in the system, such as MSC 106.

If the base station determines that the mobile station requires a second synchronization word, in step 306 the base station transmits a first time slot that includes the first synchronization word. Then, in step 308, the base station transmits at least a second synchronization word. In this method, in order to correctly demodulate and decode an unknown data symbol transmitted in a first time slot, the base station may determine a predetermined first data symbol (first synchronization word) and a predetermined second data symbol (second synchronization word). Provide both to the mobile station. In the embodiment of Figure 1, when a particular mobile station is of first type, the transmitter 112 alone or in coordination with the controller 110, during the current time slot and at least a portion of the next time slot, for transmitting a radio signal to the particular base station. Form means for responding to the form of a particular mobile station.

If the base station determines in step 304 that the mobile station does not require a second synchronization word, the base station transmits a first time slot and a first synchronization word in step 312. With respect to the embodiment of Fig. 1, when the specific mobile station is of the second type, the transmitter 112 alone, in order to transmit the adapted radio signal to another type of mobile station, in order to transmit the radio signal to the specific mobile station during the current time slot, Or jointly with the controller 110 to form a means for responding to a particular mobile station type. Next, at step 314, the base station determines that a second time slot (i.e., the time slot following the first time slot) has been allocated. If the base station is in two-way wireless communication with a second mobile station using a second time slot of the same radio channel, a second time slot is assigned. If the base station is not in communication with any mobile station during the time slot, or if the mobile stations assigned to the time slot are in different directions, transmission may be suspended or changed during the second or subsequent time slots. If a second time slot is allocated, the base station transmits a second time slot and a second synchronization word in step 316, requiring the mobile station to allocate a second time slot.

If the base station determines in step 314 that a second time slot has not been assigned, the base station determines in step 318 if a change in radio transmission is required. For example, if a second time slot is assigned to mobile stations located in different sectors of the area provided by the base station, the change is necessary. If no change is needed, then control proceeds to step 316, where a second time slot and a second synchronization word are sent. However, if a change is needed, the base station makes the change required for transmission in step 320 and transmits the next time slot in step 322. This method ends at step 310.

4 is a flow chart illustrating a method of operating a mobile station of the first type of the wireless communication system of FIG. The first type of mobile station requires or expects the base station to transmit a second synchronization word. This method begins at step 402.

In step 404, the mobile station repeats looking for control transmissions from the base station BS. If no suitable transmission is found, the mobile station continues to look. The mobile station may attempt to initiate a call by initiating a two-way wireless communication with the base station, or hand over the communication to locate a location from the first base station to the second base station.

In the context of FIG. 1, receive path 314 forms a means for receiving and decoding a signal at a remote base station. Analog front end 150, demodulator 152 and decoder 154 are adapted to do this. Alternatively, the design and implementation of such circuits, including both hardware and software as well as embodiments, are more clearly described in the references. The new indication signal provided by the present invention indicates whether the support station transmission is in the first format or the second format. The first type of transmission includes a symbol, such as a synchronization word, of a subsequent time slot that the mobile station 130 can use to decode the base station transmission. The second form of base station transmission does not certainly include the second synchronization word. To decode a communication signal received from base stations 102 and 104 in the allocation time slot of the TDMA frame period, decoder 154 coupled with controller 138 forms a means for responding to the indication. To perform this function, decoder 154 and controller 138 may be appropriately implemented by combining hardware or software.

In one embodiment, once the base station is found, for optimal performance, the mobile station informs the base station of what is needed for the second synchronization word in step 406. In other embodiments, no particular implementation of step 406 occurs. Rather, other routines or software that control the operation of the mobile station may perform the next step depending on the mode of operation of the mobile station.

If the mobile station requires a second synchronization word, it may send an indication at step 408. As described above, the indication may be data or other information included in a signal such as a control signal. For example, the control signal may be a device serial number (ESN) and a mobile station identification number (MIN) that are uniquely associated with the mobile station. The indication indicates the mobile station type to the base station and then determines whether the mobile station should transmit a predetermined second data symbol of a subsequent time slot to the assigned time slot. Alternatively, the indication may be a specific class mask or protocol version number, which is sent to the base station and used by the base station to determine if the mobile station requires transmission of a second synchronization word. In addition, the mobile station transmits identification information, such as an identification word just like a device serial number, and then the base station is used to determine the transmission requirements of the mobile station.

The mobile station receives in step 408 a first time slot and at least a second sync word transmitted by the base station. The mobile station demodulates the first time slot with the aid of the second sync word in step 410. More generally, using the decoding technique or other appropriate techniques in the aforementioned integrated reference, the mobile station demodulates and decodes the first time slot. The mobile station determines in step 412 whether more time slots are coming or if a call is received. If the call continues, control returns to step 408 again. If the call arrives, then the method ends at step 416.

5 is a flowchart illustrating a method for operating a second type of mobile station of the wireless communication system of FIG. The second type of mobile station does not require or expect the base station to send the second synchronization word. However, in one embodiment, if a second sync word is available, the second type of mobile station uses the second sync word to optimize the performance of the mobile station. The method begins at step 502. Step 504 processes as in step 404 jointly with the mobile station of the first type as described above. In step 506, the mobile station sends an indication that the second sync word can be omitted.

If the mobile station does not require a second synchronization word, the second type of mobile station may receive an indication from the base station as to whether the second synchronization word is available or not at step 508. In step 510, the mobile station receives a first time slot containing up to a second sync word. In step 512, the mobile station checks whether the second sync word is available or useful. If the mobile station indicates that the second synchronous word is available or useful, the mobile station goes to step 514 and uses a first demodulation algorithm using the first and / or second synchronous word. If the mobile station indicates that the second sync word is available or not useful, the mobile station goes to step 516 and uses a second algorithm to demodulate the first time slot using only the first sync word. Then, in step 518, the soft-decision on whether to demodulate using the first algorithm in step 514, or the demodulation using the second algorithm in step 516, from the subsequent first slot. Interleaved and decoded.

If the call continues at step 520, the flow returns to step 510 to receive the next first slot. Optionally, if an indication is provided per unit slot that the second sync word is useful, control returns to step 508 again. However, if the call arrives, the method ends at step 522.

From the foregoing, it can be seen that the disclosed embodiments provide a method and apparatus for removing or modulating transmission of some synchronization words by a base station in a mobile wireless communication system. The base station instructs the mobile station in the area provided by the base station that subsequent transmission of the synchronization word is unreliable by being suspended or changed. In an alternative embodiment, the mobile station may transmit to the base station that a second synchronization word is needed, in which case the base station continues to transmit the second synchronization word for use of the mobile station.

This embodiment allows for improved base station depolymerization using a more extended directional antenna adapted to a given receiver location that can transmit multiple time slots in a TDMA frame period in different directions. Alternatively, it is possible to use attachable power control in this embodiment where the transmit power level of the time slot may increase or decrease with the distance of the designated receiver. Both of these changes affect the characteristics of the second synchronization word. Using the embodiment described above, the extended base station can be adapted to send the second synchronization word with the signal circuit back to the previous time slot, which is suitable for returning to the mobile station receiver that trusts the second synchronization word. .

Certain embodiments of the invention have been shown and described, and variations are possible. For example, it has been shown that a synchronization word transmitted in each time slot to demodulate or decode a transmission from a base station is used by the mobile station, and any predetermined data or symbols contained within the time slot may be used by the mobile station. Can be. Therefore, claims are included to cover all such variations and modifications, in accordance with the spirit and scope of the invention.

Claims (25)

A method of operating a wireless communication system comprising at least one base station and a mobile station, the method comprising: At the base station, transmitting a predetermined first data symbol and an unknown data symbol; Selectively transmitting, at the base station, a second predetermined data symbol; At the base station, when the transmission of the predetermined second data symbol is not guaranteed, sending one indication; A method of operating a wireless communication system, comprising at least one base station and at least one mobile station, comprising, at the mobile station, decoding the transmission from the base station using at least a predetermined first data symbol. The method of claim 1, wherein decoding the transmission comprises: Decoding the unknown data symbol using only the first predetermined data symbol when the indication is transmitted; And At least one base station and at least one mobile station comprising decoding an unknown data symbol using at least one of a first predetermined data symbol and a second predetermined data symbol when the indication is not transmitted. Wireless communication system operating method comprising a. 10. The method of claim 1, wherein the first predetermined data symbol comprises a synchronization word for a current time slot. 2. The method of claim 1, wherein the second predetermined data symbol comprises a synchronization word for a subsequent time slot. The method of claim 1, wherein sending the indication is: And at least one base station and at least one mobile station, when the base station suspends synchronization word transmissions during subsequent time slots. 2. The method of claim 1, wherein sending the indication comprises; At least one comprising transmitting an indication when the base station cannot guarantee transmission of the predetermined second data symbol by any of reliable timing, reliable phase, reliable amplitude and reliable directional continuity. And a base station and at least one mobile station. The method of claim 1, At the mobile station, sending an indication indicating that the mobile station expects to transmit a predetermined second data symbol; And at the base station, in response to the indication, reliably transmitting a predetermined second data symbol, comprising at least one base station and at least one mobile station. 8. The method of claim 7, wherein the indication comprises a predetermined data pattern. 8. The method of claim 7, wherein the indication includes an operating mode indication for a mobile station. 8. The method of claim 7, wherein the indication comprises an identifier for a mobile station, the next step being: Determining, at the base station, transmission requirements for the mobile station in response to the identification word; In response to a transmission requirement for the mobile station, transmitting at least one predetermined second data symbol. 12. The method of claim 10, wherein said transmission requirement is retrieved from a subscriber database. A mobile station capable of operating in a wireless communication system, the mobile station being configured to receive signals from remote base station transmissions of the first and second forms, the mobile station comprising: Means for receiving and decoding a signal from the remote base station indicating whether the base station transmission is in the first or second form; And When the indication indicates base station transmission of the first type, due to the symbol transmitted from the base station in the subsequent time slot, the communication signal received from the base station in the allocated time slot of the time division multiple access (TDMA) frame period is decoded and Means for responding to the signal, in order to decode the communication signal in the time slot without the aid of a symbol transmitted in a subsequent unassigned time slot, when the indication indicates a base station transmission of the second type. A mobile station configured to receive signals from remote base station transmissions of the first type and the second type. A mobile station capable of operating in a wireless communication system, the mobile station being configured to receive signals from remote base station transmissions of the first and second forms, wherein the transmissions are assigned to a plurality of consecutive time slots, A receiver which receives the transmission and in response generates data including an indication having a first value when the transmission is in the first form and having a second value when the transmission is in the second form; Combined with the receiver, configured to decode data using data from the current time slot when the indication has a first value, and extract data from the current time slot and subsequent time slots when the indication has a second value. And a circuit configured to decode the data using the mobile station. The method of claim 13, A transmitter for transmitting a signal to a remote base station; And And for communicating with a remote base station, circuitry configured to format data comprising an indication instructing the base station whether the mobile station accepts a first type of transmission. A mobile station operating in a wireless communication system comprising one or more base stations transmitting during consecutive time slots. A decoder configured to confirm, when transmitting from one or more base stations, an indication as to whether to rely on a time slot subsequent to receiving; And And a demodulator for demodulating transmission during the current time slot from one or more base stations in accordance with one of the first and second algorithms in connection with the indication. 16. The mobile station of claim 15, wherein the decoder is configured to identify an indication in data received from one or more base stations. 17. The mobile station of claim 16, wherein during the initiation of bidirectional communication between the mobile station and one or more base stations, the decoder is configured to identify an indication in data received from the one or more base stations. 16. The mobile station of claim 15, wherein the decoder is configured to identify an indication of a subsequent time slot. 19. The mobile station of claim 18, wherein the decoder is configured to measure signal characteristics for transmissions from one or more base stations during subsequent time slots and to identify an indication by comparing the signal characteristics with a predetermined threshold. A base station operating in a wireless communication system and configured to transmit a signal to one or more mobile stations of a first type or a second type in a predetermined area, 17. A wireless communication with a base station, comprising: means for determining a type of a particular mobile station; And (a) when the particular mobile station is in the first form, to transmit radio signals to the particular mobile station during the current time slot and during at least a portion of the subsequent time slots, and (b) when the particular mobile station is in the second form, To transmit a radio signal to a specific mobile station during a time slot, and to transmit an adapted radio signal to another mobile station, A base station comprising means for responding to a particular mobile station type. 21. The base station of claim 20, wherein the means for determining comprises circuitry configured to determine the type of a particular mobile station based on a transmission from the mobile station. 21. The method of claim 20, wherein the means for transmitting comprises: changing a power level of a transmission in a subsequent time slot, a phase change in a subsequent time slot, a timing change in a transmission in a subsequent time slot, a change in direction in a subsequent time slot, and a transmission. And adapts the wireless signal in accordance with one of the demodulation change of and a burst format change of transmission in a subsequent time slot. At least one base station transmitting a wireless signal during the consecutive time slots including the current time slot and the subsequent time slots, the wireless signal comprising an indication indicating whether transmission of subsequent time slots is guaranteed; A time division multiple access (TDMA) wireless communication system comprising at least one mobile station for receiving a wireless signal in accordance with the indication. 24. The apparatus of claim 23, wherein when the indication indicates that transmission of a subsequent time slot is guaranteed, the at least one mobile station includes circuitry to decode the wireless signal using information in the current time slot and information in the subsequent time slot. Time Division Multiple Access (TDMA) wireless communication system, characterized in that. 24. The method of claim 23, wherein the mobile station may be in one of a form that requires guaranteed transmission of subsequent time slots and a form that does not require guaranteed transmission of subsequent time slots, wherein at least one base station is assigned to a particular mobile station. 12. A time division multiple access (TDMA) wireless communication system comprising circuitry for receiving a signal from a particular mobile station of at least one mobile station capable of indicating a form.