Multiple access cellular communication with dynamic slot allocation and reduced co-channel interference
Abstract
This record has no abstract on file.
Term
Term ended
Expired 25 December 2015, 10.7 years ago.
- Priority
- Filed
- Granted
- Expired
- Today
8 claims: 8 independent, 0 dependent
- 1フレームのスロットで情報を通信するための通信システムであって、 第一のセルと関連付けられ、 フレームのスロットを使用して 前記第一のセル内のユーザーに下りリンク情報を送信し、 フレームのスロットを使用して 前記第一のセルのユーザーから上りリンク情報を受信するように適合された第一の基地局であって、潜在的に干渉するアンテナを具備する第一の基地局と、 周波数再使用セルと関連付けられ、 フレームのスロットを使用して 前記周波数再使用セルのユーザーに下りリンク情報を送信し、 フレームのスロットを使用して 前記周波数再使用セルのユーザーから上りリンク情報を受信するように適合された第二の基地局であって、潜在的に干渉されるアンテナを具備し、 前記第二の基地局において、 前記潜在的に干渉するアンテナ からの下りリンク情報の送信が、 前記潜在的に干渉されるアンテナの上りリンク情報の受信と干渉 し得る 第二の基地局と を具備し、 前記セルの各々において、前記フレーム内の第一の部分のスロットは、上りリンク情報の通信のために予め割り当てられ、前記フレーム内の第二の部分のスロットは、下りリンク情報の通信のために予め割り当てられており、本通信システムはさらに、 前記潜在的に干渉するアンテナが、前記潜在的に干渉されるアンテナが上りリンク情報を受信する際のフレーム部分とは異なるフレーム部分で下りリンク情報を送信 し、その結果、前記潜在的に干渉するアンテナからの下りリンク情報の送信と前記潜在的に干渉されるアンテナの上りリンク情報の受信との間の前記干渉が減少するように、 前記セルの各々で前記 フレーム内の第三の部分のスロットを、前記セルの各々のユーザーからの要求に従って、上りリンク通信あるいは下りリンク通信のいずれかにダイナミックに 割り当てるための手段 を 具備する通信システム。
- 2第一のセルと関連し、 フレームのスロットを使用して 該第一のセルのユーザー に 下りリンク情報を送信し 、フレームのスロットを使用して 該第一のセルのユーザーから上りリンク情報を受信するように適合された第一の基地局を具備する通信システムにおいて、フレームの割り当てられたスロットで情報を通信する方法であって、 周波数再使用セルと関連付けられ、 フレームのスロットを使用して 該周波数再使用セルのユーザーに下りリンク情報を送信し、 フレームのスロットを使用して 該周波数再使用セルのユーザーから上りリンク情報を受信するように適合され 、潜在的に干渉されるアンテナを具備する 第二の基地局を提供するステップを備え、前記第一の基地局は、前記第二の基地局の 前記 潜在的に干渉されるアンテナでの上りリンク情報の受信と干渉 し得る、 潜在的に干渉するアンテナを具備し、 本方法はさらに、 前記潜在的に干渉するアンテナが、前記潜在的に干渉されるアンテナが上りリンク情報を受信する際のフレーム部分とは異なるフレーム部分で下りリンク情報を送信 し、結果として前記潜在的に干渉するアンテナからの下りリンク情報の送信と前記潜在的に干渉されるアンテナの上りリンク情報の受信との間の前記干渉が減少するように、前記セルの各々で、 前記フレーム内の前記スロットの第一の部分を、上りリンク通信に予め割り当てるステップと、 前記フレームの前記スロットの第二の部分を、下りリンク通信に予め割り当てるステップと、 前記フレームの前記スロットの第三の部分を、前記セルの各々のユーザーからの需要に依存して上りリンク通信あるいは下りリンク通信のいずれかにダイナミックに割り当てるステップ とを具備する方法。
- 3あるシステムセルの基地局とそのセルのユーザーとの間でフレームのスロットで情報が送信される通信システムにおいて 使用される装置であって 、 フレームのスロットを使用して、 前記あるセルの前記ユーザーに下りリンク情報を送信し、 フレームのスロットを使用して、 前記あるセルの前記ユーザーから上りリンク情報を受信するように構成された前記あるセルのアンテナ手段 であって、前記アンテナ手段は潜在的に干渉するアンテナを具備し、潜在的に干渉されるアンテナを有する周波数再使用セ ルにおいて、前記潜在的に干渉するアンテナからの下りリンク情報の送信が、前記潜在的に干渉されるアンテナの上りリンク情報の受信と干渉し得る、アンテナ手段を具備し、 前記セルの各々において、前記フレーム内の第一の部分のスロットは、上りリンク情報の通信のために予め割り当てられ、前記フレーム内の第二の部分のスロットは、下りリンク情報の通信のために予め割り当てられており、本装置はさらに、 前記潜在的に干渉するアンテナ が、 前記周波数再使用セル の前記潜在的に干渉されるアンテナ が上りリンク情報を受信する際の前記フレームのスロットとは異なる前記フレームのスロットで下りリンク情報を送信 し、その結果、前記潜在的に干渉するアンテナからの下りリンク情報の送信と前記潜在的に干渉されるアンテナの上りリンク情報の受信との間の前記干渉が減少するように、 前記あるセルの前記ユーザー からの要求に従って、前記フレーム内の第三の部分のスロットを上りリンク通信あるいは下りリンク通信のいずれかにダイナミックに 割り当てる手段 を 具備する装置。
- 4前記アンテナ手段は、 前記潜在的に干渉するアンテナを具備する 指向性アンテナの組を具備 し、前記指向性アンテナの各々は、前記第一の部分、第二の部分及び第三の部分のスロットの各々と関連付けられ、前記あるセルにおいて、前記指向性アンテナの各々は、他のセルにおける対応する指向性アンテナの各々と同じ方向に向けられる、 請求項 3 に記載の装置。
- 5前記 ダイナミックに割り当てる手段 は、前記指向性アンテナの内のどれが前記あるセルの特定ユーザーと通信するために使用されているかを識別するためのステータス情報を受信し、予め決められたスロット方向フレーム構成に従って前記特定ユーザーへのスロットの割り当てを行うように適合されたプロセッサを具備する請求項 4 に記載の装置。
- 6あるシステムセルの基地局とそのセルのユーザーとの間でフレームのスロットで情報が通信される通信システムにおいて、前記スロットを割り当てる方法であって、 フレームのスロットを使用して、 前記あるセルの前記ユーザーに下りリンク情報を送信し、 フレームのスロットを使用して、 前記あるセルの前記ユーザーからの上りリンク情報を受信するように構成された アンテナ手段を前記あるセルに 提供するステップを備え、前記アンテナ手段は 潜在的に干渉するアンテナを具備し、潜在的に干渉されるアンテナを有する周波数再使用セルにおいて、前記潜在的に干渉するアンテナからの下りリンク情報の送信が、前記潜在的に干渉されるアンテナの上りリンク情報の受信と干渉し、 前記セルの各々において、前記フレーム内の第一の部分のスロットは、上りリンク情報の通信のために予め割り当てられ、前記フレーム内の第二の部分のスロットは、下りリンク情報の通信のために予め割り当てられており、本方法はさらに、 前記潜在的に干渉するアンテナ が、 前記周波数再使用セル の前記潜在的に干渉されるアンテナ が上りリンク情報を受信する際の前記フレームのスロットとは異なる前記フレームのスロットで下りリンク情報を送信 し、その結果、前記潜在的に干渉するアンテナからの下りリンク情報の送信と前記潜在的に干渉されるアンテナの上りリンク情報の受信との間の前記干渉が減少するように、 前記あるセルの前記ユーザー からの要求に従って、前記フレーム内の第三の部分のスロットを上りリンク通信あるいは下りリンク通信のいずれかにダイナミックに 割り当てるステップ を 具備する方法。
- 7前記アンテナ手段を提供するステップは、前記潜在的に干渉するアンテナを具備する指向性アンテナの組を提供することを具備 し、前記指向性アンテナの各々は、前記第一の部分、第二の部分及び第三の部分のスロットの各々と関連付けられ、前記あるセルにおいて、前記指向性アンテナの各々は、他のセルにおける対応する指向性アンテナの各々と同じ方向に向けられる 請求項 6 に記載の方法。
- 8第一のセルと関連付けられ、 フレームのスロットを使用して 前記第一のセルのユーザーに下りリンク情報を送信し 、フレームのスロットを使用して 前記第一のセルのユーザーから上りリンク情報を受信するように適合された第一の基地局であって、潜在的に干渉するアンテナを具備する第一の基地局を有するシステムにおいて、フレームのスロットで情報を通信するための装置であって、 周波数再使用セルと関連付けられ、 フレームのスロットを使用して 前記周波数再使用セルのユーザーに下りリンク情報を送信し 、フレームのスロットを使用して 前記周波数再使用セルのユーザーから上りリンク情報を受信するように適合された第二の基地局であって、潜在的に干渉されるアンテナを具備し、 前記第二の基地局において、 前記潜在的に干渉するアンテナ からの下りリンク情報の送信が、 前記潜在的に干渉されるアンテナの上りリンク情報の受信と干渉 し得る 第二の基地局 を具備し 、 前記セルの各々において、前記フレーム内の第一の部分のスロットは、上りリンク情報の通信のために予め割り当てられ、前記フレーム内の第二の部分のスロットは、下りリンク情報の通信のために予め割り当てられており、本装置はさらに、 前記潜在的に干渉するアンテナが、前記潜在的に干渉されるアンテナが上りリンク情報を受信する際のフレーム部分とは異なるフレーム部分で下りリンク情報を送信 し、その結果、前記潜在的に干渉するアンテナからの下りリンク情報の送信と前記潜在的に干渉されるアンテナの上りリンク情報の受信との間の前記干渉が減少するように、 前記周波数再使用セルのユーザー からの要求に従って、前記フレーム内の第三の部分のスロットを上りリンク通信あるいは下りリンク通信のいずれかにダイナミックに 割り当てるための手段 を 具備する装置。
Independent claims8
61 paragraphs, as filed
[Cross Reference of Related Applications] The present invention<u style="single">US patent named "Multiple Access Method"</u><u style="single">No.5,420,851</u>This is a partial continuation application of the above, and the application has been assigned to the assignee of the present invention.
Description: TECHNICAL FIELD [0002] The present invention relates to a multiple access technology for a communication system. In particular, the present invention relates to, for example, a wireless communication system that utilizes multiplex access techniques, including allocating available frame time slots for uplink and downlink communications.
[0003] The design of a communication network or communication system is to achieve a network with desirable performance characteristics such as reliability of received information, for example, physical constraints such as the characteristics of a communication channel. And evaluate system constraints such as bandwidth per available channel. Cellular systems generally require low throughput delay of information, high reliability and high performance of information transfer, while limiting the bandwidth of each cellular frequency band.
[0004] Current wireless networks utilize multiplex access technology that multiplexes users in order to efficiently use network resources. In particular, these networks are TDMA (Time Division Multiple Access) with FDD (Time Division Duplication) as in the Pan-Europe GSM system (also known as the global system for mobile communications) and the North American IS-54 system. Use either TDMA / TDD (Time Division Duplication), a variant such as in Access) and Digital Europe Cordless Telephony (DECT) systems. See "Second Generation Radio Information Network" by DJ Goodman (IEEE Tran. Veh. Tech. VT-40, NO.2, pp. 366-374, May 1991).
[0005] In the multiple access system described here, a time frame is a basic transmission unit. Each frame is divided into multiple time slots. Some slots are used for control purposes and some slots are used for information transfer as described below. Information is transmitted between slots within a frame in which slots are assigned to a particular user. Throughout this disclosure, the term "information" should be understood to refer to data representing audio, text, video, or other digital information.
Other multiplex access technologies such as PRMA (Packet Reservation Multiplex Access) and R-ALOHA (Reservation ALOHA) recognize the burst nature of voice packets and have a system capacity by having a reservation mechanism for the time slot. Is increasing. "Packet Reservation Multiple Access for Local Wireless Communication" by DJ Goodman, RA Valenzuela, KT Gayliard, B. Ramamurthi (IEEE Trans. Comm., COM-37, No.8, pp. 885-890, August 1989) And "Packet Broadcast Network-Performance Analysis of RALOHA Protocol" by SSLam (IEEE Trans. Comp., COMP-29, No.7, pp. 596-603, July 1980). Although it can support a large number of users over the bandwidth of a channel, these approaches are limited in range and, in the case of PRMA, are rarely achieved under low latency constraints. In addition, PRMA technology requires the user to actively speak in order to respond to actual voice communication, i.e., to allocate slots instead of responding to another control mechanism for allocating slots. This allocation method leads to collisions between data packets, increasing latency and reducing throughput. In two-way conversations, only one user is active, which allows a small number of users to obtain high gain for statistical multiplexing when information from both conversation channels is multiplexed on a common channel. Other systems recognize that doing often happens. LM Paratz, EV Jones "Voice Transmission Using Adaptive Burst Mode Technology" (IEEE Trans., Comm., COM-33, No.6, pp. 588-591, June 1985) and S. Nanda, OC Yue See Variable Split Duplication for Wireless Communication (GLOBECOM '91, pp. 32.6.1-32.6.7). However, such a system was used to diminically change the bandwidth allocated to two people in a single conversation (dual voice link). Therefore, the voice quality deteriorates when both voices are talking at the same time or when both voices overlap. In addition, partial slot allocation is required, making it difficult to manage slot allocation. Thus, there is a demand for multiplex access systems that can provide high capacity, high quality, low latency communication, especially in wireless personal communication systems that compete with wired systems.
[0007] According to one aspect of the invention, multiple access techniques are disclosed and slots are dynamically allocated between uplink and downlink users. An embodiment provides a method for allocating slots in a communication system employed for communicating information within slots allocated on uplinks and downlinks between a pair of N user pairs of users. To. The method generates a set of frames, where each frame is assigned a Us slot to communicate information on the uplink, a Ds slot assigned to communicate information on the downlink, and A ( A> = 0) Includes S information slot (S = Us + Ds + A) with unused slots. Us and Ds can be dynamically changed to perfect the quality and capacity of the entire system.
[0008] In another embodiment of the invention, some of the available information slots in the frame of either the uplink user or the downlink user are permanently allocated. The remaining unallocated slots are dynamically allocated between uplink and downlink users according to demand. These other examples are referred to as partially shared time division multiplexing (PSTDD). PSTDD can be used to reduce the effects of some sort of same channel interference (CCI), which occurs, for example, in time division multiple access (TDMA) type systems with dynamic slot allocation.
[0009] Another aspect of the invention includes utilizing multiple base station directional antennas in connection with the proper allocation of frame time or frequency slots to a particular directional antenna. Corresponding slot orientation configurations of directional antennas and frames can minimize the impact of CCI resulting from, for example, uplink and downlink shared slots in neighboring frequency reuse (FR) cells of STDD or PSTDD cellular communication systems. In other embodiments, omnidirectional antennas can be used in place of a set of base station directional antennas. In addition to the additional features and advantages of the present invention, the above features will be apparent with reference to the following detailed description and accompanying drawings.
BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 shows components of a cellular or microcellular communication network. Cell 102 represents a portion of the geographic area serviced by this system. Within each cell is base station 105, which is connected to a public telephone line network. Base station 105 transmits and receives information (ie, digital data representing text, voice, video, etc.) over a payphone network, user 110-i (i = 1, ... Establish a wireless link with N). A radio link between a user vs. 110-i and base station 105 was received by the base station from the user to base station 105 and then from the uplink Ui and telephone line network to send information to the telephone line network to that user. It consists of a downlink Di for transmitting information. In general, the relationship to throughput delays and the effective use of bandwidth resources within a network can be directed by the appropriate design or utilization of modulation techniques, audio coding methods, channel coding and equalization techniques. JJC Chang, RA Miska and RA "Overview: Wireless Systems and Technology" by Shober (AT & T Tech. J., Vol. 72, No. 72, pp. 11-18, July / August 1993), "Digital in the Mobile Field" by TP Bursh Jr. and others. Radio (AT & T Technical Journal, Vol. 72, No. 4, pp. 19-26, July / August 1993) and N. Seshadri, CE.W. Sundberg, and V. Weerackody's "Modulation, Error Correction, Channels" Equalization and Other Latest Technologies (AT & T Technical Journal, Vol. 72, No. 4, pp. 48-63, July / August 1993). For example, spatial diversity can be used in connection with a small amount of channel coding to minimize delay. Low-rate voice encoders such as ADPCM, EDPCM, or LD-CELP and modulation methods such as pseudo-analog skewed DPSK are well suited to reduce delay. "Pseudo-Analog Voice Transmission of Mobile Wireless Communication Systems" by T. Miki, C.-EW Sundberg and N. Seshadri (IEEE Trans. Veh. Tech. See Vol. 42, No. 1, pp. 69-77, February 1993). Bandwidth resource relationships may be oriented through the appropriate design of multiplex access techniques. The goal of multiple access technology is to regulate communication for different user pairs in a cell given a limited number of available frequencies, a limited bandwidth per channel, and so on. In particular, proper design of multiple access systems is important when configuring low latency, high quality digital communication networks. In general, see "Digital Cellular Systems in North America" by CE.W. Sundberg and N. Seshadri (GLOBECOM '90, Vol. 1, pp. 533-537, San Diego, CA, December 1990).
FIG. 2 shows the principles of TDMA / TDD for comparison purposes with other systems. A standard TDMA / TDD has control information integrated into the header of the information sent within the transmitted information slot, but for illustration, frame 201 is divided into three parts, of which All are transmitted in the same frequency band. The control unit 205 contains information on call management. The uplink section 210 and the downlink section 215 are each divided into N slots. Thus, the uplink and downlink for each user pair can have a guaranteed slot for transmitting information. However, if a slot is assigned to each user and the user decides not to use the assigned slot (ie, does not send information between the slots), the slot will not be reassigned and the system capacity will increase. Low.
Better use of network resources can be obtained if voice users are statistically multiplexed through the use of voice activity detection (SAD). Figure 3 shows the TDMA / TDD / SAD301 format designed for use up to N user pairs. The TDMA / TDD / SAD frame 301 is divided into four parts. Uplink and downlink control units 305 and 307 include bits for handling call management functions. The uplink control unit 305 includes a bit for handling a request for the uplink information slot. The downlink control unit 307 includes a bit indicating which uplink information slot and downlink information slot are assigned to the uplink user and the downlink user who transmit and receive information. The uplink section 310 and the downlink section 315 are divided into slots. Each of the uplink and downlink has the same number of slots, less than N. SAD technology means that information transfer, especially the important part of voice conversation, consists of quiet parts and that the transmission of information does not need to occur, that is, N user pairs are active and transmit information at some point. Therefore, we recognize that there is an opportunity that not all users are using 100% of the slots assigned to them at that time. Thus, the number of slots required to satisfactorily accommodate up to N-user pairs can be meaningfully reduced through slot reallocation from inactive users to active users. The result is a large capacity (because it results in a reduction in the number of slots that do not transmit information) and a lower delay (because frames can be made shorter given the reduced number of slots). In addition, it becomes an inadequate resource to accommodate all users during peak demand, and this information is not available to slots for data transmission and / or allows new user pairs to access the system. Will be lost.
[0013] FIG. 4 shows a format of the frame 401 that is useful in realizing the present invention. The present invention, i.e., a multiplex access system called Shared Time Division Duplication (STDD), stabilizes traffic between N-user pairs, for example, dynamically allocating slots between uplink and downlink on a frame basis. It is designed to be. The frame 401 is divided into four parts. The call management function is processed by separate uplink slots and downlink slots of the uplink control unit 405 and the downlink control unit 407, as described below. The rest of frame 401 is divided into S slots (S = Us + Ds + A). Here, the Us slot is allocated for uplink information transfer, and the Ds slot is allocated for downlink information transfer. A represents the number of slots that cannot be allocated, whatever. In frame 401 of FIG. 4, A = 0. The number of slots allocated between the uplink section 410 and the downlink section 415 varies with each frame as indicated by the split section 412. However, the total number of audio slots S remains fixed for each frame. When there are a few users in the system and the total number of slots in one direction is less than S / 2, the information slots behave like TDD and the S slots are equally split for uplink and downlink access. Will be done. As the number of users increases and the number of audio slots required in either direction exceeds S / 2, the divider 412 between the uplink and downlink slots changes according to demand. The ability to share a common frequency band contributes to statistically high multiplexing gain even for narrowband systems with a limited number of users. The value of S is chosen based on three factors. They are 1) the desired quality of received information, i.e., what level of packet loss is acceptable, 2) the number of user pairs to be accommodated, and 3) the accuracy of the voice activity detector, immediately. Then, how well silence and pause can be detected during information transmission. For example, TDMA / TDD / SAD requires 46 voice slots with a high quality packet dropping rate of 0.01%, whereas in a system with N = 32 user pairs, 64 voice slots are standard TDMA. Required for / TDD. STDD generally requires 35 audio slots, assuming a 2ms second frame size at the same dropping rate. The overall statistical multiplexing gain is a function of the exact design of the control information.
[0014] FIG. 5 is a flowchart showing steps for allocating slots. In general, except for the call setup function, all signal functions belonging to call management in a cellular or microcellular system, including handoff and termination, are communicated via information in the control unit. In addition, the control information also indicates the state of transmission, i.e., whether the user is actively communicating or silent. When the user wants to send information, such as when talking, and enters the active state in step 502, the status information in the control slot assigned to the user is shown in step 504. Requests an appropriate slot in the uplink or downlink information section from the base station. Other trainings, such as random services, can be used, but in general this can be achieved using first-in first-out (FIFO) service training when allocating information slots to users. Similarly, the base station cares about all slot requests emanating from network line terminations and therefore allocates slots in step 506. Slot allocation information is carried in the downlink control information slot to both uplink and downlink users. Thus, when the downlink control information is transmitted over time, it is advantageous to precede the uplink control information so as to reduce the delay. If the slot is not assigned to the user at the time of request, the information will be dropped. When the information transfer is complete, the status information is reset in step 508 and the slots are returned to the pool of unused slots in step 510. The amount of control information is dictated by the need for call management functions and the frequency of transmission activity.
Using separate control slots and information slots mitigates the overhead efficiency issues common to PRMA-style networks, and is easy to work with voice activity detection while providing low access latency. Enables access. The uplink control unit 405 and the downlink control unit 407 may include each N control slot. However, the overhead per frame is reduced by establishing a duty cycle for the control information. For example, assume that the total number of control slots is 2C. Where C is the number of uplink or downlink control slots and N (N is a multiple of C) is the maximum number of user pairs that can be supported. In general, C <N, and therefore only C user pairs can communicate control information to or from the base station in one frame period. Thus, there is an overall K = N / C frame period for all user pairs served in this way. That is, K is a duty cycle that provides services to all users. This access mechanism guarantees that all users will be serviced within the K-frame period. At the same time, the acknowledge is communicated within the same frame period, so that a user with an acknowledged reservation can immediately send a voice packet within the same frame. When a user reserves a voice packet, the user keeps the reservation for the minimum K-frame period. For example, when the frame period is 2ms, N = 40, C = 5, the duty cycle is 8 and the cycle period is 16ms. In theory, the larger the duty cycle, the smaller the amount of control overhead information. In STDD, the appropriate cycle period is 16ms if it is conveniently synchronized with the voice activity detection rate.
[0016] Even in the STDD system, there may be a situation where not all of the information slots are used. That is, A 0 (A is not 0). This spare capacity is available for call setup when a new call arrives at this system. Suppose a new user wants to monitor the control slot for the minimum period of a cycle to check the status of the information slot. That is, it is assumed that an attempt is made to determine whether or not all slots are allocated. The system can then use the spare information slot as a controversial channel to inform the base station of this setup request, for example using random access in the form of ALOHA. If A is less than S and the number of available slots is A, a new call randomly selects one of these A slots to send its setup request packet. This request arrives at the base station successfully if there are no other users sending in the same slot. If the total number of user pairs currently in service is less than N, the new call is successfully serviced and the acknowledge is sent in the next available downlink control slot. The location of this control slot also determines the location of new calls in the control cycle stream. As mentioned above, when the number of users is small, STDD behaves as TDMA / TDD / SAD and slots are equally allocated between uplink and downlink. In this case, the spare information slot used to set up the call is treated as an information slot, and the slots are equal until conditioned on the instruction that the split between the uplink and downlink slots should be moved. It remains assigned. The above system has been described for user pairs up to N per carrier frequency. A large number of carrier frequencies carrying each user pair up to N can be used in high traffic areas.
Although the above embodiments have primarily focused on voice transmission, STDD can be used, for example, for mixed traffic conditions where some slots carry data and some carry voice. Is. STDD may also be implemented in variable rate mode per user, eg, variable audio quality mode in which a large number of bits are assigned to customer-requested video or high quality audio. The control channel contains the appropriate information. Thus, this method has the advantage that it can be used when there is high-bandwidth / narrow-band information transfer between users. In another embodiment, on demand, dynamic slot allocation between uplinks and downlinks is achieved by frequency division when information is carried over dynamically assigned orthogonal frequency channels. Alternatively, in code division mode, the traffic is carried directly by sequence spectral diffusion in a pseudo-orthogonal code, or by a combination of time division, frequency division, and code division techniques. In other embodiments, the STDD format can be used in connection with pseudo-analog skewed DPSK modulation technology to further reduce throughput delays in communication systems. A more detailed description of the pseudo-analog skewed DPSK modulation is disclosed in the above-mentioned reference "Pseudo-analog voice transmission in a mobile wireless communication system" by T. Miki et al. By citation, this reference is incorporated here.
[0018] The above detailed description has described how slots in a frame are dynamically allocated between uplink and downlink users. This method is not limited to any particular hardware or software. Alternatively, this method has been described so that it can be readily adapted to those skilled in the art or as preferred hardware or software. The above exemplary STDD technology improves wireless communication systems, but in some embodiments performance is limited by factors such as same channel interference (CCI) and run length of dropped packets.
FIG. 6 shows some types of CCI that occur in TDMA / STDD cellular communication systems. The first cell 600 includes a base station 601 for transmitting downlink information to the mobile user 602 and then receiving uplink information. Cell 600 operates at channel carrier frequency F1. User 602 transmits the uplink packet to the base station at frame 604 at carrier frequency F1. Frame 604 includes one or more uplink time slots 606, which are dynamically assigned to user 602 according to STDD technology, as described above. The second cell 610 includes a base station 611 for communicating with a user in the cell 610. Cell 610 also operates at channel carrier frequency F1, and cells 600 and 610 are therefore referred to as adjacent frequency reuse (FR) cells. The mobile user 612 in cell 610 receives a downlink packet from base station 611 in frame 614. Downlink packets are sent in one or more time slots in frame 614 and they are dynamically assigned to user 612 according to STDD technology. Both mobile users 602 and 612 and base stations 601 and 610 are equipped with omnidirectional antennas in this example.
[0020] Unlike the TDD technique in which fixed time slots are assigned to uplink and downlink transmissions, the STDD technique of the present invention dynamically shifts the time slot to either uplink or downlink transmission depending on the requirements. Allows you to be assigned. FIG. 6 shows that the user 602 can transmit information to the base station 601 in the uplink slot 606 while the base station 611 in the adjacent FR cell 610 is transmitting to the user 612 in the downlink slot. There is. Since the signal transmitted from the base station often has a meaningfully higher power level than the signal transmitted from the mobile user, the downlink signal transmitted in slot 616 is transmitted in slot 606. Interferes with the uplink signal. The interference between frame time slots 616 and 606 is shown by dotted line 620 in Figure 6. The interference signal is indicated by the dotted line 630. This type of CCI is referred to herein as a "mixed" CCI because it includes a high power downlink signal 630 from the base station that interferes with the reception of the low power uplink signal from the mobile user. In some cases, this type of interference results in a signal-to-noise ratio (S / I) at base station 601 resulting in dropped packets in uplink time slot 606. Mixed CCI in STDD systems meaningfully increases the packet dropping rate, thereby reducing system capacity. The mixed CCI includes uplink signals from other users that interfere with reception by one user with downlink signals transmitted from the base station in the same time slot. The latter type of mixed CCI is not a serious problem due to the fact that base station transmit power is significantly higher than that of mobile users.
[0021] Mixed CCI generally does not occur in properly synchronized conventional TDMA / TDD and TDMA / TDD / SAD systems. However, these traditional systems represent "regular" CCI resulting from interference between two different downlink signals or between two different uplink signals within an adjacent FR cell. Regular CCI is common to most cellular systems that utilize frequency reuse to extend system capacity, and the distance between adjacent FR cells is such that regular CCI is at or below acceptable levels. Is selected for. The remaining regular CCI in STDD systems is generally not greater than that in traditional TDMA / TDD and TDMA / TDD / SAD systems, provided that mixed CCI can be compromised or mitigated. There will be.
The present invention provides a number of techniques that can be used to reduce mixed CCI in STDD systems. One technique involves alternating uplink and downlink slots within a STDD frame and is called Partially Shared Time Division Duplication (PSTDD). Others include the use of directional base station antennas for both reception and transmission in relation to the proper slot orientation configuration of the STDD frame. These techniques may be used together or separately. The CCI reduction technique has been described in connection with the STDD example, but it will be appreciated by those skilled in the art that the technique is generally applicable to some multiplexed communication system in which uplink and downlink slots are dynamically assigned. It will be clear.
FIG. 7 shows another STDD frame 701 according to the present invention. The frame 701 includes an uplink control unit 705, a downlink control unit 707, an uplink information unit 710, and a downlink information unit 715. The STDD frame 701 also contains a group of shared slots 720. Supply slot 720 represents a subset of the total number of available information transmission slots in frame 701. The uplink unit 710 and the downlink unit 715 include slots permanently allocated for uplink information transmission and downlink information transmission, respectively. Frame 701 is shown in the embodiment that the number of unused slots A is equal to 0, while other embodiments contain a value of A greater than 0. Sections 710 and 715 are thus similar to sections 310 and 315 of frame 301 in FIG. The shared slot 720 is dynamically allocated between uplink and downlink transmissions as requested, similar to the slot allocations in sections 410 and 415 of FIG. In the exemplary frame 701, therefore, a subset of the entire available information slot is dynamically allocated, while the remaining information slots are assigned to either uplink or downlink transmission. The other STDD technology is called PSTDD. The potential for mixed CCI is reduced because only a subset of the available slots are dynamically allocated. The shared portion of the entire available information slot is specified by the partial sharing factor η, so another PSTDD technique is called PSTDD (η). In a PSTDD (η) system with the sum of S time slots for information transmission, there are (S / 2) (1-η) slots available only to uplink users and only to downlink users (S / 2). ) (1-η) slots, and the remaining Sη slots are shared between uplink and downlink users upon request. Generally, a PSTDD system with a partially shared factor η between about 15% and 25% Represents a packet drop rate similar to those of the corresponding STDD system, but can provide a reduction in mixed CCI. Other partially shared factors η may also be available.
[0024] FIG. 8A shows an exemplary wireless communication system 800 according to the present invention. The geographical area serviced by System 800 is divided into cells arranged in a hexagonal pattern based on a cell group in which the central cell is surrounded by six cells. For clarity of illustration, only some of the cells in System 800 are shown. A large number of frequency reuse (FR) cells 810-i are shown in solid lines. Each of the FR cells 810-i shares at least one common channel carrier frequency. Thus, cells 810-i represent a subset of the total number of cells in system 800. Other cells utilizing different channel carrier frequencies are placed adjacent to each of the FR cells 810-i, some of which are indicated by dotted lines. The particular cell pattern shown in System 800 is for illustration purposes only and the present invention is also available in systems with any of a number of other cell patterns. The FR cell adjacent to and surrounding a FR cell 810-i is the adjacent FR cell, which is referred to herein as a potential interferer in the "first layer". There are a total of six first layer potential interferers for each FR cell 810-i in the hexagonal FR pattern of the seven cells in Figure 8A. A downlink signal from an adjacent FR cell of an FR cell produces a mixed CCI within that cell as described above. The 7-cell hexagonal pattern is generally repeated in this system such that the outer cell 810-i of one 7-cell group is the central cell 810-i of the other 7-cell group. As used herein, the term "adjacent FR cell" is intended to include cells that give rise to CCI within a cell, and thus further away from the first layer interferer as well as the cell. It is also intended to include cells.
In this exemplary embodiment, each cell includes base station 814, which communicates with users in the cell via three directional antennas A, B, and C. Mobile users within the geographic area serviced by System 800 can communicate with each other and with public telephone networks via base station 814. The directional antennas in a cell are configured so that each antenna transmits over an area defined by an angle of about 120 ° (degrees) with respect to the cell's base station 814. In this embodiment, the three directional antennas A, B, and C together provide a full 360 ° communication cover around a base station 814. Of course, other embodiments will provide a number of other coverages. If used with a conventional cellular system STDD slot allocation technique utilizing a directional antenna and a 7-cell hexagonal FR pattern, it would be vulnerable to mixed CCI. The present invention provides directional antenna placement and corresponding slot orientation frame configurations, which together greatly reduce mixed CCI. Directional antennas are primarily referred to herein as separate antennas, but it will be apparent to those skilled in the art that directional antennas here may be implemented as separate sectors of the same multi-sector antenna, for example. ..
[0026] FIG. 8B shows an exemplary slot directional frame configuration, which is used in connection with the directional antennas A, B, C of FIG. 8A to reduce mixed CCI in system 800. In the example described below, it is assumed that the frame portion that follows the slot directional configuration contains only the information time slot of that frame, but the frame control information is configured in the same way, or, for example, in omnidirectional configuration. It may be transmitted and received. FIG. 8B shows the time period for a particular base station directional antenna to receive uplink information and transmit downlink information during a certain STDD frame 850. The uplink portion 852 of the frame 850 is assigned to receive uplink information via a directional antenna. The uplink unit 852 is divided into three sub-parts A, B, and C, and one of the three directional antennas between each of them receives the uplink information from the user. The downlink portion 854 of the frame 850 is assigned to transmit downlink information to the user via the directional antenna. The downlink section 854 is also divided into three sub sections, and one of the three directional antennas transmits downlink information between them. The same frame configuration is utilized by each of the cell base station and the mobile user in system 800. However, it should be noted that antenna and frame configuration changes may be used, for example, in cells at the edge of the system. The additional part 856 of the frame 850 contains a slot that cannot be assigned to either uplink or downlink communication. During peak demand, slots in part 856 are assigned to either the uplink or the downlink as described above.
It will be described how the frame configuration shown in FIG. 8B reduces mixed CCI. Ai, Bi, Ci are used to refer to a directional antenna in a cell 810-i. The directional antennas of the central FR cell 810-0 within the group of 7FR cells 810-i shown in FIG. 8A are referred to as A0, B0, C0. Six outer cells 810-i Numbered from the top cell as the first cell 810-1, the remaining cells are numbered clockwise starting from cell 810-1. Mixed CCI occurs, for example, if directional antenna A0 attempts to receive an uplink signal from the user during the same time slot that directional antennas C1, B2, C2 are sending the downlink signal to the user. .. Antennas C1, B2 and C2 are thus potentially interfering antennas, and antenna A0 is a potentially interfering antenna in system 800. Thus, the exemplary frame configuration of FIG. 8B allows, for example, the directional antennas C1, B2, and C2 to transmit the downlink signal during a time when the antenna A0 is not receiving the uplink signal. Similar mixed CCI scenarios occur between other first layer interfering cells 810-i and central cell 810-0, and between other cells in System 800. The frame 850 is configured to minimize overlap between uplink and downlink time slots utilized by potentially interfering directional antennas. Figure 8B shows that an uplink user of a directional antenna Ai is serviced between a frame in front of the uplink user of the directional antenna Bi and Ci. Similarly, the downlink user of antenna Ai is serviced between a frame in front of the downlink user of antenna Bi and Ci. It will be apparent to those skilled in the art that any of a number of other frame configurations can be used to minimize mixed CCI according to the invention. For example, the downlink users of antennas Ci and Bi are, for example, Ante. Since the downlink users of A1 and A2 generally do not interfere with the uplink users of antenna A0, they could be serviced after them in Ai. Alternatively, the order of the antennas in the frame may be completely reversed, or the position assigned to antenna B in the frame may be swapped with the position assigned to antenna C. These other slot orientations should be applied consistently to each non-end cell in the system. Yet other slot orientation frame configurations may utilize other permutations of the exemplary order shown in FIG. 8B.
FIG. 9A shows another exemplary cellular communication system 900 according to the invention. System 900 includes a large number of FR cells 910-i arranged in a 7-cell hexagonal pattern. An additional cell 910-i is also shown. Each of the cells comprises a base station 914 and four 90 ° directional antennas designated by A, B, A', and B'. Antennas A and B are arranged to transmit and receive in directions substantially opposite to those of antennas A'and B'. Mixed CCI occurs in system 900, for example, when a downlink slot assigned to antenna A'or B'in one cell interferes with uplink reception of antenna A or B in an adjacent FR cell.
FIG. 9B shows an exemplary frame configuration that may be utilized in System 900. The frame 950 is separated into an uplink section 952 and a downlink section, and the uplink information is received by the directional antenna in the order of A', B', B, and A in the uplink section, and the downlink information is received in the downlink section. Is transmitted by the antenna in the order of A, B, B', A'. Addendum 956 represents a time slot that is not used in the exemplary frame 950. In cell 910-i, the center cell of the 7-cell group of FR cells is designated as cell 910-0, the top cell in the group is the first cell 910-1, and the remaining outer cells in the group are cell 910-1. Numbered in clockwise order starting with. The directional antennas in cells 910-i are referred to as antennas Ai, Bi, Ai'and Bi'. The exemplary frame configuration shown serves the uplink user of Antenna Ai, which is the last among the uplink users. Downlink users are served by potentially interfering antennas such as Ai'in a time slot as far away from the frame uplink / downlink boundaries as possible to reduce mixed CCI. Again, many other slot-oriented frame configurations suitable for use with 90 ° directional antennas, including configurations that utilize the opposite antenna order, will be readily apparent to those skilled in the art.
[0030] With reference to FIG. 9A, another aspect of the invention involves determining an appropriate angle of rotation Θ for a directional antenna configuration within a cell. For example, 90 ° or 45 In a cellular system with a directional antenna, proper selection of the angle of rotation Θ minimizes the number of potential interferences in the cellular system. The angle of rotation Θ is measured in this example as the angle between one end of the directional antenna and the solid line 920 connecting the nearest FR cell 910-5 to the base station 914 of cell 910-10. An angle of rotation may be identified by another FR cell that poses potential interference when that angle is used. These potential interferences are characterized here as being in the inner (m, n) step in the FR pattern from a cell, and the angle of rotation is therefore expressed as Θ (m, n). Various possible angles of rotation Θ (m, n) are shown in FIG. 9A. The cells along line 920, namely cells 910-5, 910-4, and 910-15, are represented as (1,0), (2,0) and (3,0) in (m, n) notation, respectively. It is specified. Similarly, cells 910-6, 910-0, and 910-3 along line 930 are designated as (1,1), (2,1) and (3,1) and cells along line 940. 910-1 and 910-2 are designated as (1,2) and (2,2), respectively. It should be noted that the (m, n) notation is adopted to facilitate the characteristics of the angle of rotation Θ, and other notations are also available.
FIG. 9A shows the angles of rotation Θ (3,1) and (2,2), at which the angle of rotation Θ (3,1) causes the potential interference cell 910-3 to move away from cell 910-10. At step (3,1) in the FR pattern, at angle of rotation Θ (2,2), potential interference cell 910-2 is at step (2,2) in the FR pattern away from cell 910-10. .. In general, a cell that is in the (m, n) step away from the cell involved is a potential interferer for that cell. After a certain number of (M, 1) steps in the FR pattern, the effect of interference from the separated potential interferers (M, 1) steps is negligibly small. Therefore, the value of the angle of rotation Θ suitable for use in reducing the mixed CCI includes values in the following range.
[0032] [Number 1]<img file="JP3667845B2_D0001.tif" />As mentioned above, a value of Θ equal to 0 is one of the directional antennas on a line such as line 920 connecting certain cells associated with the center of any one of the first layer FR cells. Corresponds to aligning the ends. In a system with a hexagonal cell pattern, the value of Θ (m, n) that gives additional interference is given by the following formula.
[Number 2]<img file="JP3667845B2_D0002.tif" />Here, rem (n, 2) is equal to 0 when n is even and equal to 1 when n is odd. Appropriate values for the angle of rotation Θ are therefore within the above specific range below and below the upper limit.
[Number 3]<img file="JP3667845B2_D0003.tif" />[0033] For example, the upper limit Θ (M, 1) for M = 5 is about 10.9 °. This means that if a value of Θ less than 10.9 ° is selected, interference from all cells less than or equal to the distance from cell (5,1) is minimal. It means that it will be done. On the other hand, interference from cells located beyond that distance from a cell is considered negligible. Choosing an appropriate angle of rotation Θ can thus improve system performance by limiting the number of adjacent FR cells that are potential interferers to a cell. As shown in system 900 of FIG. 9A, the same angle of rotation Θ may be used for each of the cells in that system. The use of a 90 ° directional antenna and a suitable rotation angle Θ is superior to that of the 120 ° directional antenna described above in connection with Figure 8A in the exemplary 7-cell hexagonal system shown. Although shown in an embodiment with a 90 ° directional antenna, the rotation angle selection technique can be used in other embodiments of the invention, including, for example, one with a 45 ° directional antenna. ..
FIG. 10A shows an embodiment of the present invention utilizing a 60 ° directional antenna. System 1000 contains a number of external FR cells 1010-i arranged around central cell 1010-0 in a 7-cell hexagonal pattern. Many non-FR cells are indicated by a dotted line adjacent to FR cells 1010-6. Each cell comprises a base station 1014 that communicates with the user across 60 ° directional antennas A, B, C, A', B', C'. In this embodiment, the uplink of antenna A is potentially interfered with by the downlink of antenna A'. B's uplink is potentially interfered with by B'downlink. The same applies hereinafter. As in the above embodiment, each cell in the system 1000 has the same antenna configuration arranged at substantially the same angle of rotation. In this embodiment, the angle of rotation Θ measured from line 1020 is about 30 °. The above determination of the appropriate angle of rotation is, for example, in an embodiment utilizing a 7-cell hexagonal pattern with a 30 °, 60 ° 120 ° arrangement, such an antenna configuration is substantially when used in a hexagonal pattern. It should be noted that it does not need to be executed because it is symmetrical.
FIG. 10B shows an exemplary slot orientation frame configuration suitable for use with the system of FIG. 10A. As in the above embodiment, the potentially interfering antenna uplinks and downlinks are assigned different time slots. The frame 1050 is separated into an uplink section 1052 and a downlink section 1054. At the uplink section, the directional antenna receives uplink information in the order of A', B', C', C, B, and A, and downlink is received. In the link section, the antenna transmits downlink information in the order of A, B, C, C', B', and A'. Again, other slot orientation frame configurations can be used, including, for example, opposite antenna order configurations. The 60 ° directional antenna configuration in Figure 10A, along with the projected frame configuration in Figure 10B, virtually reduces mixed CCI in System 1000, and in a 7-cell hexagonal system, 120 ° and 90 above. It is possible to provide better performance than that of the antenna embodiment. Further reduction of mixed CCI may be achieved by constructing the frame according to the above technique and increasing the number of directional antennas to reduce the coverage angle of each antenna. For example, another possible embodiment would utilize twelve 30 ° directional antennas. As mentioned above, the present invention may be utilized in a system with a variety of different cell patterns. Further details on frequency reuse and cell patterns can be found, for example, in the "Cellular Concept" by VH MacDonald (Bell System Technical Journal, Vol. 58, No. 1, pp. 15-41, January 1991). It is incorporated here by citation. It can also be found in "Mobile Wireless Communications" by R. Steele (Pentech Publishing, 1992).
The exemplary examples of FIGS. 8, 9, and 10 show, for example, the worst mixed CCI scenario experienced in the heart of the system. A central FR cell has other FR cells on all sides, so the potential for mixed CCI is greatest. However, the FR cells at the edge of this system have less potential for mixed CCI, so these cells will be able to utilize different antenna configurations than the cells at the center. For example, the cells at the edges of the system may utilize fewer directional antennas than the central cell. One of ordinary skill in the art will readily be able to determine other suitable changes to the antenna configuration and / or frame configuration used in the cells at the end of the system.
[0037] In another embodiment of the present invention, an omnidirectional base station antenna may be used instead of the directional antenna shown in FIGS. 8, 9 and 10. In these embodiments, the frame configuration is such that, for example, the potentially interfering omnidirectional antenna in the first cell receives the uplink information from the potentially interfering omnidirectional antenna in the adjacent FR cell. Is also modified in the adjacent FR cell to send downlink information to another part of the frame. In one preferred embodiment, uplink slot allocations begin at one end of a frame and downlink slot allocations begin at the opposite end of the frame, similar to that shown in FIGS. 8B, 9B, 10B. Thus, if an excessive number of frame slots are present, the unused slots are placed in the center of the frame, such as parts 856, 956, 1056 above. This allocation technique can provide a buffer between the uplink and downlink slots in some situations and thus tends to reduce mixed CCI. One of ordinary skill in the art will be able to readily determine other suitable frame configurations for use in the indentured antenna embodiment of the present invention.
FIG. 11A is a block diagram showing an exemplary base station downlink 1102 according to the present invention. Baseband input signals representing voice, text, video, or other information are received at a base station, for example, from a public telephone line network. The baseband signal is processed by the voice encoder 1105 and the channel encoder 1110 as is well known to those skilled in the art. The coded information signal is fed to the modulator 1115 and then to the RF transmit hardware 1120, which drives the directional antennas A, B, C described above in connection with the system 800 of FIG. 8A. The downlink processor 1125 encodes element 1105-1120 so that the downlink information is transmitted from the user to the appropriate directional antennas A, B, C in the order specified in the exemplary frame configuration of FIG. 8B. , Modulate and transmit. Any of a number of techniques may be utilized in downlink 1102 to achieve the desired slot direction frame configuration. For example, control information that identifies a particular user and the corresponding antenna may be used by the downlink processor 1125 to determine which time slot should be assigned to a user to provide the desired frame configuration. The present invention may be used in various systems with a control information duty cycle of K> = 1. One of ordinary skill in the art can easily determine appropriate adjustments in the placement and / or processing of control information for systems with K> 1. Assigning a particular time slot to an antenna may occur after voice coding and / or channel coding, and before modulation, or at any of many other points on downlink 1102.
[0039] FIG. 11B shows an exemplary base station uplink 1132. The RF receiving hardware 1140 processes and guides the uplink information signal received from the user via the directional antennas A, B, and C. The received uplink signal is demodulated by the demodulator 1145 and then decoded by the channel decoder 1150 and the voice decoder 1155 to generate a baseband output signal that is supplied, for example, to a public telephone line network. The uplink processor 1160 guides the reception, demodulation and / or decoding operations of element 1140-1155 to receive the uplink signal for the appropriate part of a frame with antennas A, B, C. This can be achieved by achieving proper system timing and control, as is well known to those skilled in the art. The downlink 1102 and the uplink 1132 may also include a channel interleaver and a channel deinterleaver, respectively, both of which are implemented as are well known to those of skill in the art. Interleaving / deinterleaving may be included, for example, as part of channel coding / decoding. Processors 1125 and 1160 are coded / decoded, modulated / demodulated and RF transmitted / It is shown to interact with the receiving child, but it should be emphasized that this is for illustration purposes only. The processing capabilities that result in the desired slot orientation frame configuration may be incorporated into one or more of the other system elements rather than being provided by another processor. In addition, the system according to the invention may include components other than those shown. For example, one of ordinary skill in the art will recognize that the present invention is suitable for use in a system without channel coding. Channel coding / decoding and interleaving / deinterleaving randomize the channels, thereby mitigating the effects of channel fading, for example, which is generally paid for the increased overall delay. Other preferred embodiments therefore utilize one of the many well-known spatial diversities that reduce channel coding and channel interleaving and direct channel fading.
It will be recognized that certain processing elements similar to those shown in base station downlink 1102 and base station uplink 1104 are also present in transmitters and receivers utilized by mobile system users. .. Processors 1125 and 1160 may be a properly programmed digital computer or microprocessor, application-specific integrated circuits, or a combination of software, hardware, and firmware that can provide the desired slot orientation frame configuration. Additional details regarding transmission, modulation, coding, and control information suitable for use with the present invention are described, for example, in "Shared Time Division Multiplexing: Low Delay" by WC Wong, CE.W. Sundberg and N. Seshadri. , Approach to High Quality Wireless Digital Voice Communication (IEEE Tran. Veh., November 1994), which is incorporated here by citation.
FIG. 12 is a flowchart for explaining the operation of an exemplary embodiment of the present invention. Step 1202 indicates that a determination is made first as to whether a particular user has entered the active state, that is, the requested allocation of information slots. If so, the status information sent by the user in the control slot is used in step 1206 to identify the base station directional antenna with which the user is communicating. Step 1212 indicates that a particular slot is assigned according to a predetermined slot orientation frame configuration, and step 1218 indicates that the user communicates with the base station in the assigned slot. If the user remains active for the next frame, the determination made in step 1224 guides the processor back to step 1206 and allocates the next frame slot according to a predetermined slot orientation configuration. After the user is deactivated, step 1230 indicates that the status information in the control slot corresponding to the user will be reset. Any slot assigned to that user is returned to the unused slot pool in step 1236. Each time a particular user requests a time slot, a determination is made as to which directional antenna the user is communicating with. The final allocation of available slots to the user is performed so that the directional antenna is utilized according to the coarse slot orientation configuration. It should be noted that the dynamic slot orientation frame allocation of the present invention may be used to improve capabilities, for example in TDMA / TDD / SAD systems. In such applications, the uplink and downlink signals of the TDD system are always transmitted at different parts of the frame, so they can be used for all directional antennas in cells that have the same time slot. However, a number of additional issues arise when applying the above techniques to TDD systems. For example, mobile users If is always "visible" by two or more directional antennas, the slot assigned to that user cannot be reused by any of the corresponding base stations, resulting in fewer available information slots. become. In addition, handoffs within cells, which are TDD systems, are more meaningful in traditional omnidirectional systems, which means that the user must be assigned a different time slot, which increases control information. There may be as many handoffs as there are.
By using circular interleaving and / or fast voice activity detection (FSAD) to reduce the run length of dropped packets, the present invention provides additional performance improvements in STDD systems. Circular interleaving and FSAD in the STDD system is<u style="single">A US patent entitled "Multiple Access Cellular Communication with Circular Interleave and Reduced Drop Packet Run Length"</u><u style="single">No. 5,602,836</u>It is disclosed in. It is incorporated here by citation.
The present invention provides a number of techniques for allocating frame slots in multiple access systems. Another embodiment includes a frequency division multiplexing (FDM) system in which the slot assigned to the user represents one of a number of available carrier frequencies. An example is a shared frequency division multiplexing (SFDD) system. In such FDM embodiments, similar antenna configurations may be used and time frames may be considered frequency frames. Here, the frame slot is intended to include, for example, both time and frequency. The STDD technique can therefore be readily adopted by one of ordinary skill in the art to provide suitable frame frequency configurations such that the mixed CCI is substantially reduced in the FDM system.
[0044] The above description has primarily shown the utility of the invention by a cellular network incorporating STDD multiplex access technology, but the devices and methods of the invention are suitable for use in wireless communication systems where same channel interference occurs. It will be understood that. Many changes can be made in the configurations shown, including frequency reuse patterns and formats, the number and format of directional antennas, the allocation of frame time slots to certain directional antennas, and the angle of rotation of the antennas. Is. These and other changes to the configurations shown will be readily apparent to those of skill in the art.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows components of a cellular communication system.
FIG. 2 is a diagram showing a conventional TDMA / TDD frame format. FIG. 3 is a diagram showing a conventional TDMA / TDD / SAD frame format.
FIG. 4 shows a shared time division multiplexing (STDD) frame format.
FIG. 5 is a flowchart showing a slot allocation step in a frame of the present invention.
FIG. 6 shows "mixed" same-channel interference (CCI) in an exemplary wireless STDD communication system.
FIG. 7 shows a partially shared time division multiplexing (PSTDD) frame format according to the present invention.
FIG. 8A shows an exemplary STDD cellular communication system with a 120 ° directional antenna and reduced CCI according to the present invention.
FIG. 8B shows a slot direction frame configuration suitable for use in the system of FIG. 8A.
FIG. 9A shows an exemplary STDD cellular system with a 90 ° directional antenna and reduced CCI according to the present invention.
FIG. 9B shows a slot direction frame configuration suitable for use in the system of FIG. 9A.
FIG. 10A shows an exemplary STDD cellular system with a 60 ° directional antenna and reduced CCI according to the present invention.
FIG. 10B shows a slot direction frame configuration suitable for use in the system of FIG. 10A.
FIG. 11A is a block diagram showing exemplary base station uplink and downlink processing elements in a cellular communication system according to the invention.
FIG. 11B is a block diagram showing exemplary base station uplink and downlink processing elements in a cellular communication system according to the invention.
FIG. 12 is an exemplary flow chart showing steps involved in supplying a portion of a frame to a directional antenna according to the present invention.
[Code description] 600,610 Cell 601,611 Omnidirectional and directional antenna 604,614 Frame with link packet 602,612 Mobile user 630 Radio 606,616 Relative packet (up and down)
Every citation, both ways
| Document | Relation | Office |
|---|---|---|
| JP05268147A | Cites | Japan |
| JP04306924A | Cites | Japan |
| JP63180229A | Cites | Japan |
| JP04094228A | Cites | Japan |
| JP03022639A | Cites | Japan |
| JP63099642A | Cites | Japan |
| JP61001125A | Cites | Japan |
28 members in 8 offices
Priority claims5
| Document | Office | Kind | Date |
|---|---|---|---|
| 08364579 | United States of America | – | |
| 36457994 | United States of America | A | |
| 36457994 | United States of America | A | |
| 1994364579 | – | – | – |
| US19940364579 | – | – | – |
Members28
| Document | Office | Kind | |
|---|---|---|---|
| NO944404D0 | Norway | D0 | |
| EP0654916A2 | European Patent Office (EPO) | A2 | |
| CA2135950A1 | Canada | A1 | |
| FI945507A | Finland | A | |
| NO944404L | Norway | L | |
| US5420851A | United States of America | A | |
| JPH07203545A | Japan | A | |
| EP0654916A3 | European Patent Office (EPO) | A3 | |
| CA2162753A1 | Canada | A1 | |
| CA2162938A1 | Canada | A1 | |
| EP0720321A1 | European Patent Office (EPO) | A1 | |
| EP0720405A2 | European Patent Office (EPO) | A2 | |
| JPH08274740A | Japan | A | |
| JPH08289360A | Japan | A | |
| US5594720A | United States of America | A | |
| US5602836A | United States of America | A | |
| CA2162753C | Canada | C | |
| CA2162938C | Canada | C | |
| EP0720405A3 | European Patent Office (EPO) | A3 | |
| CA2135950C | Canada | C | |
| JP3510409B2 | Japan | B2 | |
| JP3667845B2This record | Japan | B2 | |
| EP0720321B1 | European Patent Office (EPO) | B1 | |
| DE69535827D1 | Germany | D1 | |
| ES2313717T3 | Spain | T3 | |
| EP0720405B1 | European Patent Office (EPO) | B1 | |
| DE69536134D1 | Germany | D1 | |
| ES2360661T3 | Spain | T3 |
18 legal events, as the office reported them to INPADOC
Over the term
Point at a mark for the eventEvents
| Event | Code | |
|---|---|---|
| Cancellation because of completion of termEXPY | EXPY | |
| Receipt of annual feesJAPANESE INTERMEDIATE CODE: R250R250 | R250 | |
| Receipt of annual feesJAPANESE INTERMEDIATE CODE: R250R250 | R250 | |
| Renewal fee payment (event date is renewal date of database)FPAY | FPAY | |
| Renewal fee payment (event date is renewal date of database)FPAY | FPAY | |
| Renewal fee payment (event date is renewal date of database)FPAY | FPAY | |
| Renewal fee payment (event date is renewal date of database)FPAY | FPAY | |
| Renewal fee payment (event date is renewal date of database)FPAY | FPAY | |
| Renewal fee payment (event date is renewal date of database)FPAY | FPAY | |
| Renewal fee payment (event date is renewal date of database)FPAY | FPAY | |
| Renewal fee payment (event date is renewal date of database)FPAY | FPAY | |
| Certificate of patent or registration of utility modelJAPANESE INTERMEDIATE CODE: R150R150 | R150 | |
| First payment of annual fees (during grant procedure)JAPANESE INTERMEDIATE CODE: A61A61 | A61 | |
| Written decision to grant a patent or to grant a registration (utility model)JAPANESE INTERMEDIATE CODE: A01A01 | A01 | |
| Decision of grant or rejection writtenTRDD | TRDD | |
| Transfer to examiner for re-examination before appeal (zenchi)AppealJAPANESE INTERMEDIATE CODE: A911A911 | A911 | |
| Written amendmentJAPANESE INTERMEDIATE CODE: A523A521 | A521 | |
| Decision of refusalJAPANESE INTERMEDIATE CODE: A02A02 | A02 |
Numbers
- Publication
- 3667845
- Publication, DOCDB
- 3667845
- Publication, EPODOC
- JP3667845B
- Application
- 33626895
- Application, DOCDB
- 33626895
- Application, EPODOC
- JP19950336268
Titles2
- Japanese
- スロットダイナミック割り当てと同一チャンネル干渉の減少を有する多重アクセスセルラー通信
- English
- Multiple access cellular communication with slot dynamic allocation and reduced same channel interference
Classification
- CPC, 8
- H04B7/2656
- H04W72/541
- H04J3/1694
- H04W16/02
- H04W16/12
- H04W16/24
- H04W72/0446
- H04W74/04
- IPC, 12
- H04J3 00
- H04B7 24
- H04B7 26
- H04J3 16
- H04L12 56
- H04W16 02
- H04W16 12
- H04W16 14
- H04W16 24
- H04W28 04
- H04W72 54
- H04W74 04