JP2003527785A - Non-stationary sectorized antenna - Google Patents

Abstract

(57) [Summary] A subscriber station that is stationary or moves at a low speed is not disadvantageous with respect to receivable services. A base station to which a cell boundary moves is described. By moving cell boundaries, stationary or slow moving subscriber stations are not penalized for receivable services. In a first exemplary embodiment, the sectorized antenna structure is in motion, either by rotating the antenna structure or by periodically varying the angle of the antenna structure. In a second embodiment, two separate antenna structures having different coverage area portions are provided, and communication is provided alternately from each of the two antenna structures. A further advantage is that the localization of the subscriber station's position can be improved by employing the additional information available using the above-mentioned motion or multi-shaped sectors.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to wireless communication. In particular, the present invention uses a non-stationary wireless antenna. A new and improved method and apparatus for transmitting wireless communication signals.

[0002]

[Prior art]

FIG. 1 shows a conventional three-sectored radio base station 100 with transmit antennas 108A, 108B and 108C functioning as geo-sectors 106A, 106B and 106C, respectively. The subscriber station 102 has an antenna 108.
It is located near the center of the effective area of B. Subscriber station 104 is in sector 10
It is located near the boundary between 6B and 106C. The antenna beam pattern from the current antenna is for the subscriber station 1 because the signal strength decreases near the sector edges and the interference between the two sectors is maximum at the border.
02 is advantageously located with respect to subscriber station 104 in being serviced by either antenna 108B or antenna 108C.

One method of compensating for sufficient service to subscriber station 104 is by subscriber station 1
04 is in a softer handoff with sectors 108C and 108B. A more flexible handoff process is the process of placing a subscriber station in simultaneous communication with multiple sectors of a base station. A more flexible handoff is "method and apparatus for performing handoff between sectors of a common base station".
Are described in detail in US Pat. No. 5,625,876. This patent is assigned to the assignee of the present invention and incorporated herein by reference. More flexible handoffs are a specific form of more flexible handoffs. Flexible handoff refers to redundant communication to multiple base stations and is described in US Pat. No. 5,101,501 entitled “Method and System for Providing Flexible Handoff in Wireless Communication Systems”. Described. This patent is assigned to the assignee of the present invention and incorporated herein by reference.

Flexible and more flexible handoffs have become less common as the demand for greater capacity of the system, combined with the desire to provide a greater variety of services to customers, such as high speed wireless digital data. Becomes less desirable. Flexible handoff requires that the same information be transmitted redundantly, which reduces system capacity. This condition is exacerbated in the transmission of high speed data, which requires significant resources to transmit each version of high speed data.

Two methods have been introduced to address the effects of flexible handoff while maintaining the goal of maximizing system throughput. The first method is to selectively assign available rate combinations to a subscriber station according to the location of the subscriber station and whether the subscriber station is in a flexible or more flexible handoff. . For example, subscriber station 102 is allowed to communicate at a higher rate than subscriber station 104, because it requires less resources to communicate with subscriber station 102 than it does to subscriber station 104. An example of this form of rate allocation is described in US patent application Ser. No. 08 / 835,632 filed Apr. 8, 1997, entitled “Method and Apparatus for Reverse Link Data Rate Scheduling”. This application is assigned to the assignee of the present invention and incorporated herein by reference.

Another method is to prevent flexible handoffs and force the selection of transmitters to communicate with a given subscriber station. Such a system is described in US patent application Ser. No. 08 / 963,386 ('386 application) filed Nov. 3, 1997 under the title "Method and apparatus for packet data transmission at higher rates". To be done.
This application is assigned to the assignee of the present invention and incorporated herein by reference.
In the '386 application, a subscriber station measures the strength of signals from neighboring base stations and sectors of the base station as well as a message indicating the identity of the base station transmitting the strongest signal received by the subscriber station. , A rate indication indicating the rate for the selected communication according to the strength of the strongest signal received by the subscriber station.

[0007]

[Problems to be Solved by the Invention]

The disadvantage of these methods is that in the case of stationary or slow moving subscriber stations, the disadvantage, even if not permanent, is long-term, which is located near the cell boundary and It is unfair for users who are slow or move slowly.

[0008]

[Means for Solving the Problems]

The present invention provides a new and improved method for transmitting data in a wireless communication system that does not penalize stationary or slow moving subscriber stations due to their proximity to cell boundaries. Regarding the device. The present invention describes a base station with moving cell boundaries. By moving the cell boundaries, stationary or slow moving subscriber stations are not penalized for receivable service.

In the first exemplary embodiment, the sectorized antenna structure is placed in motion either by rotating the antenna structure or by periodically varying the angle of the antenna structure. In the second embodiment, two separate antenna structures with different coverage area portions are provided, and communication is provided alternately from each of the two antenna structures.

A further advantage of the present invention is that the localization of the position of the subscriber station may be improved by adopting the additional information available using the above-mentioned movement or multi-shaped sectors. That is.

[0011]

DETAILED DESCRIPTION OF THE INVENTION

The features, objects, and advantages of the present invention will become more apparent from the following detailed description when referring to the drawings. Like reference numerals refer to corresponding parts throughout the drawings.

FIG. 2 is a block diagram illustrating the operations performed by the present invention. Block 20
At 0, a signal for transmission is generated. In the exemplary embodiment, the generated signal is a code division multiple access communication signal. Generating code division multiple access communication signals is described in "Systems and Methods for Generating Signal Waveforms in Mobile Phone Systems".
Are described in detail in US Pat. No. 5,103,459. This patent is assigned to the assignee of the present invention and incorporated herein by reference.

In an exemplary embodiment of the invention, the waveforms generated are for high speed wireless data, as described in aforementioned US patent application Ser. No. 08 / 963,386. The present invention is applicable to other forms of code division multiple access, such as the Telecommunications Industry Association (Telecomm
It is also applicable to the standards of the Unications Industry Association (IS-95 family) and the proposed third generation standards, such as those described in WCDMA and cdma2000. However, the invention is equally applicable to other modulation formats, such as GSM or TDMA, where slow moving or stationary subscribers are disadvantaged by their position within the base station coverage area. .

At block 202, the waveform is provided to the non-stationary antenna. In the exemplary embodiment, the antenna is a sectorized antenna.
The sector boundaries are made movable to eliminate geographical penalties for slow moving and stationary subscriber stations. In the preferred embodiment of the present invention, the sectors are moved at a rate slower than the rate of the data rate request feedback loop and power control of the communication system. However, the movement of sector boundaries is swift for the duration of service for subscriber stations.

At block 204, the signal is transmitted from the non-stationary antenna. In the first embodiment, the sectorized antenna structure is rotated by coupling the antenna structure to a motorized platform or by using multiple phased array antenna structures. . This rotation can be oscillatory or continuous over a constrained angle of rotation.
In the second embodiment, the non-stationary antenna takes shape by providing multiple sets of sectorized antenna combinations and switching the transmission of signals between the sectorized antenna combinations.

At block 206, the signal transmitted through the non-stationary antenna is received by a subscriber station within the coverage area of the base station. This signal is demodulated and provided to the subscriber station user.

At block 208, the signal strength of the signal received from the transmitting base station is measured at the subscriber station.

At block 210, the subscriber station transmits its communication signal to the base station. The communication signal comprises, in the exemplary embodiment, a message indicating the measured signal strength.

At block 212, the signal transmitted by the subscriber station is received at the non-stationary antenna structure.

A further advantage of the present invention is that in the transmission of forward link signals, location localization can benefit from a non-stationary antenna structure. In the first exemplary embodiment of sweeping the forward link signal, the signal strength is the leading edge of the sweep antenna coverage beam because the sector sweeps in a predictable manner towards the subscriber station. Indicates that the subscriber station is near. The reported change in signal strength is used to estimate the location of the subscriber station.

Alternatively, the location localization is performed by alternation (al) from multiple sets of fixed antenna combinations.
ternating) Forward link signal transmission can be benefited. The signal strength reported by the subscriber station varies based on the antenna structure from which the forward link signal was transmitted. These changes in the reported signal strength are used to estimate the location of the subscriber station. In an exemplary embodiment, the control processor can employ trigonometric techniques for two separate sectorizations, and in each of these sectorizations, the The difference in the reported energies can be noted as the subscriber station is determined to be in close proximity.

Under certain conditions, it may be desirable for the antenna used for transmission of the forward link signal to be mobile, while the antenna for reception remains fixed. Conversely, under certain conditions it may be desirable for the antenna used for reception of the reverse link signal to be mobile, while the antenna for transmission remains fixed. One possible reason for placing the moving beam structure on one link and not the other is that a more flexible handoff may be supported on one link and not the other. Is. These and other modifications will be readily apparent to those skilled in the art without departing from the scope of the invention.

FIG. 3 is a simplified block diagram illustrating a first embodiment of a transmission system for a sectorized base station 320. Data to be transmitted are three streams 31
8A, 3l8B and 3l8C. Data 3l8A, 3l8B and 3l
Each 8C stream has a corresponding waveform generator 300A, 300B and 30.
Processed for transmission by 0C. The processed stream of data is then provided to the corresponding antennas 3l4A, 3l4B and 3l4C of antenna structure 312. In the first exemplary embodiment, the antenna structure 312 is
The antennas 300A, 300B and 300C are operably coupled to a rotator mechanism 316 that changes the angle at which the transmissions are directed. In an alternative embodiment,
The effect of motion provided by mechanical means can take the form of the use of phased array antennas, or beam reflectors, or other means without departing from the scope of the invention.

In an exemplary embodiment, rotator 316 comprises a motor that fully rotates antenna structure 312 about its axis at a substantially constant angular velocity. In an alternative embodiment, the rotator 316 may cause the antenna structure 312 to move in a limited angular combination such that the movement of the antenna structure 312 turns in a clockwise followed by an alternating angular combination in a counterclockwise manner. The angle of structure 312 is changed.

In the exemplary embodiment, a subscriber station in communication with base station 320 indicates the sector of the base station from which the subscriber station is receiving the strongest signal, and A message is sent to base station 320 requesting that data be transmitted for it based on strength. In the preferred embodiment, the base station 32 depends on the latency of the rate request feedback loop.
In the transmission time by 0, the angular motion is performed at a rate selected to be slow enough so that the rate request information is still applicable. The mobile station measures this received signal, generates its rate request message and sends this message.
The base station receives the message, processes the data for transmission at the rate determined according to the message, and transmits the data. Importantly, when transmitting data by the base station, the angle has not changed by more than an acceptable threshold from the position at which the subscriber station measured the signal strength on which the request was based. . This situation is equally applicable to other related feedback loops in other systems such as power control feedback loops.

A representative block diagram of waveform generator 300 is shown within waveform generator 300A. Data for transmission is provided to frame formatter 302.
In the exemplary embodiment, frame formatter 302 generates a combination of cyclic redundancy check bits and attaches these bits, along with trailing bits and overhead message bits, to the information for transmission. This information is provided to encoder 304. The encoder 304 can be any form of forward error correction coder, such as a convolutional encoder, a turbo encoder, or the like. The encoded symbols are provided to interleaver 306, which permutes these symbols to provide more time diversity within the transmitted data.

This data is then provided to modulator 308. In an exemplary embodiment,
Modulator 308 is a high data rate CDMA modulator, as described in the '386 application. The present invention has the additional advantage in a system not prepared for more flexible handoff on the forward link, but with the proposed third generation CDM.
It is also useful in systems that provide more flexible handoff on the forward link, such as A systems and IS-95 based CDMA systems.

In the exemplary embodiment, each signal is different for each sector of base station 320, such that each signal is spread by each sector of base station 320 such that the signals transmitted through antennas 31 4 A, 3 14 B and 3 14 C are spread using different PN sequences, respectively. Use to spread. The modulated signal is provided to transmitter 310, where antenna structure 3
As it is transmitted through 12, it is filtered, upconverted and amplified.

FIG. 4 shows another embodiment of the present invention. In a second embodiment, the physical movement of the transmitting antenna is replaced by switching between two or more fixed antenna structures pointing in different directions. Data for transmission is waveform generator 400A, 4
00B and 400C, which process signals as described for waveform generator 300A.

The processed signal is provided to switch 402. First, switch 402 directs the processed signal to first antenna structure 404A, where the signals processed by waveform generators 400A, 400B, and 400C are transmitted to antenna 406A.
, 406B and 406C, respectively. After a predetermined time interval, switch 402 directs the processed signal to antenna structure 404B, where the signals processed by waveform generators 400A, 400B and 400C are transmitted to antenna 4
08A, 408B and 408C respectively. One of ordinary skill in the art will appreciate that any number of fixed antenna structures can be employed without departing from the scope of the present invention.

FIG. 5 shows alternating sectorization of the cell coverage area using two fixed antenna structures. The first sectorization pattern is the solid lines 502A, 502B and 50.
2C, which is provided by antennas 408A, 408B and 408C. A second sectorized pattern is shown by dashed lines 500A, 500B and 500C, which is provided by antennas 406A, 406B and 406C.

In an exemplary embodiment of the invention, the switching is performed by a guard time, where the base station 410 is based on the rate request information being based on measurements of signals transmitted from different antenna structures. Decide that. In an alternative embodiment, the switch 402 operates at a rate beyond the system's feedback loop so that the subscriber station measures the strength of the received signal and sends the message. The base station switches to another antenna structure and returns to the initial state prior to transmission to the subscriber station. In this aspect, the rate request information is still relevant to the antenna structure over which the data is transmitted. Many ways of synchronizing the selection of transmission rate with measurement feedback will be readily apparent to those skilled in the art without departing from the scope of the invention.

FIG. 6 is a simplified block diagram of the subscriber station 616 of the present invention. The signal is received by the antenna 600 and is transmitted through the duplexer 602 to the receiver (RC
VR) 604. The receiver 604 down-converts, amplifies, and filters this received signal, as well as demodulates the received signal into a demodulator 606 and a searcher 608.
To provide.

In the exemplary embodiment, demodulator 606 demodulates the received signal according to a CDMA demodulator structure, and in particular according to the CDMA waveform structure described in the '386 application. In the exemplary embodiment, the demodulator is a RAKE well known in the art.
Operates according to structure. The RAKE demodulator separately demodulates the signals arriving at the subscriber station via different propagation paths. This provides additional path diversity that results in more reliable demodulation. A typical RAKE demodulator structure is US Pat. No. 5,109,3 entitled “Diversity Receiver in CDMA Mobile Phone System”.
No. 90. This patent is assigned to the assignee of the present invention and incorporated herein by reference.

The received signal is also provided to searcher 608. Searcher 608 searches for other signals transmitted by base stations and sectors near the subscriber station and measures the energy of these signals. In an exemplary embodiment, a message is generated by a message generator (MSGGEN) 610 indicating the base station of the strongest received signal and indicating the rate requested by the base station determined according to the strength of the received signal. In an alternative embodiment, the message indicates the measured signal strength for multiple base stations and sectors.

This message is provided to modulator 612 and merged into the reverse link traffic signal for transmission. This reverse link signal is then sent to the transmitter (TMTR
) 614. Transmitter 614 upconverts, filters, and amplifies the signal for transmission. This signal is provided through duplexer 602 for transmission from antenna 600.

In the exemplary embodiment, the receive antennas are similarly rotated or switched so that the reverse link transmission of a subset of subscriber stations near the sector boundaries is not geographically disadvantaged.

FIG. 7 shows the receiving subsystem of the base station of the present invention. The reverse link signal is received at receiving subsystem 712 of antenna structure 700. In the first exemplary embodiment, the antenna structure 700 is coupled to the rotator 740. In the exemplary embodiment, rotator 740 comprises a motor that causes antenna structure 700 to rotate fully about its axis at a constant angular velocity. In an alternative embodiment, the rotator 740 causes the antenna structure 700 to move in a limited angular combination such that the movement of the antenna structure 700 turns in a clockwise followed by an alternating angular combination in a counterclockwise manner. The angle of structure 700 is changed.

The reverse link signals are received by antennas 702A, 702B and 702C and provided to receivers 706A, 706B and 706C, respectively. Receiver 706A,
706B and 706C downconvert, filter, and amplify the received signal and provide the received signal to 708A, 708B, and 708C, respectively. In the exemplary embodiment, demodulators 708A, 708B and 708C are code division multiple access communication systems. Again, those skilled in the art will appreciate that the present invention is not limited by the modulation format used on each link. The demodulated symbols are then provided to control processor 710.

In the exemplary embodiment, the demodulated signal includes a message from the subscriber station indicating the strength of the signal received by the subscriber station. The information in the message is
Used by the base station to determine from which antenna the base station should transmit for each subscriber station within the coverage area. The consequences of keeping stationary and slow moving subscriber stations in motion may result in more flexible handoffs when prepared by the base station because the antenna boundaries move. Will be the same as A more flexible handoff is the aforementioned US Pat. No. 5,625.
No. 876 is described in detail.

A further advantage of the present invention is that location localization can benefit from a sweep of the forward link signal. As the sector sweeps towards the subscriber station in a predictable manner, the signal strength indicates the proximity of the subscriber station to the leading edge of the sweep antenna coverage beam. These changes in the reported signal strength are used by the control processor 710 to estimate the location of the subscriber station.

FIG. 8 shows an alternative embodiment of the base station receive subsystem of the present invention. Second
In one embodiment, the physical movement of the receiving antenna is replaced by switching between two or more fixed antenna structures pointing in different directions.

First, the switch 406 receives a signal from the first antenna structure 800A, where the signal is received through antennas 802A, 802B and 802C and provided to the receiving subsystems 808A, 808B and 808C. Receive subsystem 808 downconverts, filters, amplifies, and demodulates the received signal. After a predetermined time interval, switch 806 switches the received signal to be provided from antenna structure 800B, where the signal is antenna 804A, 804B and 80.
4C and is provided to receiving subsystems 808A, 808B and 808C. Receive subsystem 808 downconverts, filters, amplifies, and demodulates the received signal.

Returning to FIG. 5, there is shown sectorization of the cell coverage area. The first sectorization pattern is shown by solid lines 502A, 502B and 502C, which is accepted by antennas 802A, 802B and 802C. The second sectorization pattern is shown by dashed lines 500A, 500B and 500C, which is antenna 8
Accepted by 04A, 804B and 804C.

A further advantage of the present invention is that location localization can benefit from alternating forward link signaling. The signal strength reported by the subscriber station varies based on the antenna structure from which the forward link signal was transmitted. These changes in the reported signal strength are used by the control processor 810 to estimate the location of the subscriber station. In an exemplary embodiment, the control processor can employ trigonometric techniques for two separate sectorizations, and in each of these sectorizations, the The difference in the reported energies can be noted as the subscriber station is determined to be in close proximity.

The above description of the preferred embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be used with other embodiments without the use of inventive capacity. Will be applicable to. Therefore, the present invention is not limited to the embodiments shown herein, but is intended to be given the broadest scope consistent with the principles and novel features disclosed herein.

[Brief description of drawings]

[Figure 1]   The figure which shows the communication system of the base station divided into three.

[Fig. 2]   6 is a flowchart showing a typical embodiment of an operation according to the present invention.

FIG. 3 is a block diagram showing elements in the first embodiment of the transmission subsystem of the base station according to the present invention.

FIG. 4 is a block diagram showing elements in the second embodiment of the transmission subsystem of the base station according to the present invention.

FIG. 5 is a diagram showing a six-sectored base station communication system configured in accordance with a second embodiment of the present invention.

[Figure 6]   FIG. 3 is a block diagram illustrating a representative subscriber station according to the present invention.

FIG. 7 is a block diagram showing elements in a receiving subsystem of a base station according to the present invention that employs a rotating receiving antenna structure.

FIG. 8 is a block diagram showing elements in a reception subsystem of a base station according to the present invention that employs an alternating reception antenna structure.

─────────────────────────────────────────────────── ─── Continuation of front page (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, BZ, CA, CH, CN, CR, CU, CZ, DE, DK, DM, DZ, EE, ES, FI, GB, GD, GE, GH , GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, UZ, VN , YU, ZA, ZW F terms (reference) 5K022 EE01 EE21 EE31 5K067 AA22 BB04 CC10 CC24 DD45 EE02 EE10 EE46 JJ74 KK02 KK03 KK13 [Continued summary]

Claims (20)

[Claims] 1. A base station comprising: a waveform generator for generating a wireless communication signal; and a multi-directional antenna structure for propagating the wireless communication signal along a changing propagation path. 2.   The multi-directional antenna structure is   At least one antenna operably coupled to the rotator;   A rotator for changing the direction of the at least one antenna, The base station according to claim 1, further comprising: 3. The base station according to claim 2, wherein the rotator rotates the at least one antenna about a central axis at a substantially constant angular velocity. 4. The base of claim 2, wherein the rotator rotates the at least one antenna within a limited angular combination to alternate between clockwise and counterclockwise rotation. Station. 5. The base station of claim 2, wherein the at least one antenna comprises three antennas operably coupled to a mobile platform. 6.   The base station according to claim 1, wherein the base station is a CDMA base station. 7. The multi-directional antenna structure is between a plurality of antennas, a first subset of the antennas of the plurality of antennas, and at least another subset of the antennas of the plurality of antennas. The base station according to claim 1, further comprising a switch that alternately provides the communication signal. 8. The at least one further subset of antennas is a second subset of antennas, and the direction in which the second set of antennas is directed is the first subset of antennas.
8. The base station according to claim 7, which divides a coverage area of the subset of 2 into two. 9.   The base station according to claim 7, wherein the base station is a CDMA base station. 10. The first subset of antennas comprises three antennas and the second subset of antennas comprises three antennas; and the first subset of antennas and antennas. Antennas in said second subset of are oriented 120 ° apart from each other; said second subset of antennas comprises three antennas; said first subset of antennas; And each antenna in the second subset of antennas is oriented 120 ° apart from each other, and the second subset of antennas is offset by 60 ° from the direction of the first subset of antennas. 9. The base station of claim 8, comprising: 11. A multi-directional antenna structure for receiving the reverse link wireless communication signal along a varying propagation path, and a receiver subsystem for demodulating the reverse link wireless communication signal. The base station according to claim 1, comprising. 12. The method according to claim 12,   The multi-directional antenna structure is   At least one antenna operably coupled to the rotator;   A rotator for changing the direction of the at least one antenna, The base station according to claim 11, further comprising: 13. The base station according to claim 12, wherein the rotator rotates the at least one antenna about a central axis at a substantially constant angular velocity. 14. The base of claim 12, wherein the rotator rotates the at least one antenna within a limited angular combination to alternate between clockwise and counterclockwise rotation. Station. 15. The base station of claim 12, wherein the at least one antenna comprises three antennas operably coupled to a mobile platform. 16.   The base station according to claim 11, wherein the base station is a CDMA base station. 17. The multi-directional antenna structure is between a plurality of antennas, a first subset of the antennas of the plurality of antennas, and at least another subset of the antennas of the plurality of antennas. The base station according to claim 11, further comprising a switch that alternately provides the communication signal. 18. The at least one further subset of antennas is a second subset of antennas, and the direction in which the second set of antennas is directed is the first subset of antennas.
18. The base station according to claim 17, wherein the coverage area of the subset is divided into two. 19.   The base station according to claim 17, wherein the base station is a CDMA base station. 20. The first subset of antennas comprises three antennas and the second subset of antennas comprises three antennas; and the first subset of antennas and antennas. Antennas in said second subset of are oriented 120 ° apart from each other; said second subset of antennas comprises three antennas; said first subset of antennas; And each antenna in the second subset of antennas is oriented 120 ° apart from each other, and the second subset of antennas is offset by 60 ° from the direction of the first subset of antennas. 19. The base station according to claim 18, comprising: