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WO1999018685A1 - Procede et appareil de communication de donnees pour accroitre le debit sur la base de la qualite du canal de communication - Google Patents

Procede et appareil de communication de donnees pour accroitre le debit sur la base de la qualite du canal de communication Download PDF

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Publication number
WO1999018685A1
WO1999018685A1 PCT/US1998/016152 US9816152W WO9918685A1 WO 1999018685 A1 WO1999018685 A1 WO 1999018685A1 US 9816152 W US9816152 W US 9816152W WO 9918685 A1 WO9918685 A1 WO 9918685A1
Authority
WO
WIPO (PCT)
Prior art keywords
data
channel
quality
blocks
burst
Prior art date
Application number
PCT/US1998/016152
Other languages
English (en)
Inventor
Nicholas P. Alfano
Cameron Fraser
Original Assignee
Motorola Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Motorola Inc. filed Critical Motorola Inc.
Priority to AU87665/98A priority Critical patent/AU8766598A/en
Publication of WO1999018685A1 publication Critical patent/WO1999018685A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
    • H04L1/0025—Transmission of mode-switching indication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0006—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission format
    • H04L1/0007—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission format by modifying the frame length
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L2001/0092—Error control systems characterised by the topology of the transmission link
    • H04L2001/0093—Point-to-multipoint

Definitions

  • This invention relates to a method of data communication in bursts of data over a communications channel, such as a radio channel and it relates to apparatus for performing such a method.
  • Data communications systems generally operate according to a logical hierarchical architecture such as the well established OSI model.
  • a logical hierarchical architecture such as the well established OSI model.
  • messages or files from a high level application are formatted into packets or packet fragments in a transport or network layer and the packets or packet fragments are sent over the communications channel as one or more bursts of signal.
  • error coding is added to the source data in one or more of the intermediate levels of the architecture, and typically, an acknowledgement request (ARQ) protocol is used whereby the recipient acknowledges complete or partial receipt of a burst of signals or negatively acknowledges failure to receive a burst of signals.
  • ARQ acknowledgement request
  • the error coding can be used by the ARQ protocol to ascertain whether a burst of singal is correctly received.
  • each layer of a heirarchical communications architecture adds some degree of overhead signaling in the form of headers containing Protocol Control Information to data received from a higher level. There is a need generally to minimize the amount of additional signaling added to the data while achieving a robust and reliable communications link in varying 0 conditions.
  • FIG. 1 is a sketch diagram of a cell of a cellular communications system with remote terminals in accordance with the invention.
  • FIG. 2 is a protocol layer diagram illustrating a first embodiment of the invention in the context of a cellular digital packet data (CDPD) system.
  • CDPD digital packet data
  • FIG. 3 is a diagram illustrating transmission bursts in a second embodiment of the invention in the context of a GSM packet radio system (GPRS).
  • GPRS GSM packet radio system
  • FIG. 4 is a circuit diagram illustrating circuit details of a communications unit (either a base station or a remote terminal) for implementation of either the first or second embodiment of the invention.
  • a cell 10 of a cellular radio system which can be a CDPD or GSM radio system is illustrated. It will be understood that the cell 10 can equally be a stand-alone site of a trunked radio system.
  • a base station 11 having a transceiver 12 and a controller 13.
  • the transceiver 12 gives a received signal strength indication (RSSI) 15 to the controller 13 and exchanges data with the controller 13 over data lines 16.
  • RSSI received signal strength indication
  • data communication takes place between the base station 11 and the remote units 20 and 21 in bursts.
  • a single burst may be sufficient to carry the complete message.
  • several bursts from a remote unit to the base station or from the base station to a remote unit may be necessary in order to transfer the complete message, datagram or file (generally referred to herein as a "message")-
  • the message is packetized or fragmented and each packet or fragment of a packet is sent in a single burst (or a number of packets are sent in a single burst).
  • a burst is a quantity of burst level overhead signaling.
  • acknowledgement request (ARQ) data such as data indicating the packet length
  • acknowledgement or a negative acknowledgement or a partial acknowledgement there is an acknowledgement or a negative acknowledgement or a partial acknowledgement.
  • ARQ acknowledgement request
  • the present invention recognizes that greater efficiency of use of the channel can be achieved by maximizing the proportion of burst level payload data (i.e. user data plus any error code or other high level overhead data) to burst level overhead signaling.
  • channel usage is increased or maximized by adjusting the proportion of data to burst level overhead signaling according to a change in quality of the channel.
  • a change in quality can be measured by RSSI or by bit error rate (BER) or it can be inferred from the rate of return of negative acknowledgements (NACKs).
  • BER bit error rate
  • NACKs negative acknowledgements
  • a CDPD protocol is shown as comprising an internet protocol (IP) packet layer 50, a subnetwork dependent convergence protocol (SNDCP) layer 51, or mobile data link protocol (MDLP) layer 52 and a medium access control (MAC) layer 53.
  • IP internet protocol
  • SNDCP subnetwork dependent convergence protocol
  • MDLP mobile data link protocol
  • MAC medium access control
  • data from an application layer (not shown) above IP layer 50 is inserted into user data field 55 of the IP layer 50.
  • the user data field is variable in length, from 1 to 64k bytes and a typical size is 2048 bytes. To this field is added a header 56 of 80 bytes.
  • the IP layer packets are segmented into SNDCP layer packets 60, 61 of 128 bytes each. Each SNDCP layer packet comprises a 2-byte header 63 and a 126-byte user data field 64.
  • SNDCP layer packets are inserted into MDLP layer frames 70, 71 etc., one packet per frame and to each packet is added front and rear flag fields 72 and 73 as well as 48 bit header field 74.
  • the MDLP layer frames are block coded into Reed-Solomon blocks of 385 bits per block.
  • the Reed-Solomon (R-S) coding scheme can be variable or adaptive to channel conditions but is preferably fixed. I.e. a fixed proportion of error coding is added to the MDLP layer frames.
  • a predetermined number M of blocks 83-86 of R-S coded data are formed together into a single transmission burst 88 and to these M blocks are added a dotting sequence 80 (in the case of a remote unit-to-base station transmission), a synchronization and 81 and a ramp down period 82 equal to 38 bits.
  • the number M of R-S blocks in a burst is never greater than a predetermined parameter referred to as MAXBLOCKS.
  • the burst length in the MAC layers 53 has an upper limit and any excess of frames (not shown) in the MDLP layer 52 that cannot be inserted into a single MAC layer burst must be inserted into a subsequent MAC layer bust (not shown).
  • User data field 55 in the IP layer is variable in length and can theoretically be any size, but practically speaking, 64,000 bytes would be a very large packet. IP packets are typically 128 to 4096 bytes in length.
  • the parameter MAXBLOCKS sets the upper limit or the number of R-S blocks that can be transmitted during a single transmission burst. If a base station receives more than MAXBLOCKS continuous blocks in the same burst, it exits its receive state and signals a decoding failure (see CDPD system specification Release 1.1, January 17, 1995 page 402-33 section 5.2.3.2). In existing systems, this parameter is fixed at system installation time and can only be adjusted manually. According to the present invention, this parameter is adjustable according to channel quality. Channel quality can be measured in a number of ways. As an example, the base station 11 can receive R-S blocks from a remote unit 20 and, in decoding those blocks, it can measure a bit error rate.
  • transceiver 12 receives radio frequency
  • Transceiver 12 also provides controller 13 with a received signal strength indication (RSSI) on line 15. Controller 13 averages the RSSI value over time, giving an average RSSI for all bursts and therefore an average RSSI for all remote units in the coverage area, regardless of their distance from the base station 11 and regardless of intervening obstacles, reflections or interferences. (As an alternative, however, base station 11 measures RSSI values for individual remote units). From the measured RSSI, base station controller 13 computes a
  • MAXBLOCKS value The value is preferably computed according to a predefined function but could be obtained from a look-up operation in a table stored in memory (not shown). Higher values of RSSI are mapped in such a table to higher values of MAXBLOCKS and lower values of RSSI are mapped to lower values of MAXBLOCKS. The relationship is not necessarily linear. The exact mapping is of no great significance. As an example, MAXBLOCKS is set to 80 blocks where the average RSSI is high and 48 blocks where the average RSSI is low, but these values do not represent extremes.
  • the base station 11 transmits the MAXBLOCKS parameter in a special broadcast message to all remote units (e.g. using a broadcast address). On receipt of the broadcast message, each remote unit stores the new MAXBLOCKS parameter and overwrites any previously set MAXBLOCKS parameters.
  • Future transmission bursts sent by the remote units 20 and 21 are formatted into MAC layer frames so that the number of R-S blocks of data in a frame (and hence a burst) does not exceed the new value.
  • a remote unit can, of its own accord, set an upper limit on a burst size which is less than MAXBLOCKS. It may choose to do this if it senses .an
  • base station 11 sends individually selected values of MAXBLOCKS addressed to individual remote stations and selected according to a channel quality parameters measured for a given remote station- to-base station path.
  • the system takes advantage of the good channel by sending more blocks in a burst.
  • the proportion of used data (RS blocks 83, 84 etc.) to burst overhead data (dotting sequence 80, sync word 81, rampdown 82 and any reverse channel ACK) is increased, (i.e. the ratio of error coded data to burst level overhead signaling is increased) making the channel usage more efficient.
  • the ratio of error coded data to burst level overhead signaling is decreased by reducing the parameter MAXBLOCKS.
  • FIG. 3 shows a GPRS multiframe in an uplink 100 (ie. remote unit-to-base station) and a downlink 101 (ie. base station-to-remote unit).
  • FIG. 3 shows that each of the uplink and downlink is formed of slots or bursts and an uplink physical radio channel 102 and a downlink physical radio channel 103 are shown illustrating that the uplink 100 is time-division multiplexed onto every 8th slot 110, 111, 112 etc. of the uplink physical radio channel 102.
  • the downlink 101 is also multiplexed onto every 8th slot of the downlink physical radio channel 103.
  • a random access burst 120 is sent by a remote unit (eg. remote unit 20) on the uplink 100.
  • a remote unit eg. remote unit 20
  • TSG 126 allocating further traffic TSGs 128 and 130.
  • further allocations (not shown) are made in the downlink 101 for transmission of an ACK during traffic downlink TSG 140 and a response during traffic uplink TSG 141.
  • the figure is not to scale.
  • the size of one or more of the time slot groups is adjusted in response to channel conditions.
  • the size of the uplink TSG 125 is increased in downlink TSG 123 when the channel quality is good and decreased when it is bad. It can readily be seen that extending the size of uplink TSG 125 in good channel conditions can obviate the need for downlink TSG 126. This would be the case if uplink TSG 125 were expanded in size sufficiently, to include uplink TSGs 128 and 130. With such a modification, the efficiency of usage of the uplink channel is increased in good channel conditions. There are efficiency gains in usage of the downlink channel also by way of a reduction in time slot group overhead signaling and a reduction in acknowledgment request signaling.
  • the remote unit 20 comprises a transmitter 201 and a receiver 202, both coupled to a duplexer 203 and, through the duplexer, to an antenna 204.
  • a synthesizer 205 is coupled to each of the receiver 202 and the transmitter 201.
  • a demodulator 210 is coupled to receiver 202.
  • a modulator 211 is coupled to the synthesizer 205.
  • a logic unit 220 is coupled via data lines 221 and 222 to the demodulator 210 and modulator 211, respectively, and is coupled by control lines 223 and 224 to the demodulator 210 and the receiver 202 and to the transmitter 201 respectively.
  • a received signal strength indication (RSSI) line 212 passes from the receiver 202 to the logic unit 220, but this is optional.
  • a control bus 226 is coupled between the logic unit 220 and the synthesizer 205.
  • Logic unit 220 is shown, by way of example, as comprising an error decoding circuit 213 and an error coding circuit 214 and a burst formatter 234. It may additionally or in the alternative include an error detect circuit and an error check generating circuit (not shown) and a timing circuit 229.
  • RAM random access memory
  • EPROM electrically erasable programmable readonly memory
  • I/O interface 235 connected to host data terminal 22.
  • the processor 230 receives from the data terminal 22 a message or file for transmission.
  • the processor 230 performs segmentation and fragmentation (if required).
  • processor 230 adds headers 63 in the SNDCP layer and fields 72 and 74 in the MDLP layer. Resultand frames are supplied by processor 230 to logic unit 220.
  • error coding circuit 214 generates Reed-Solomon coded data blocks, and burst formatter 234 adds dotting sequence 80 and synchronization word 81 to each burst and timing circuit 229 controls the timing of outputting of the resultant transmission burst data to the modulator 211.
  • processing at a higher layer than the physical layer can be performed by the logic unit 220.
  • physical layer processing including the error coding can be performed by the processor 230.
  • Processor 230 and logic unit 220 can be integrated together in a single microcontroller or application specific integrated circuit.
  • the logic unit 220 passes the data of each resultant transmission burst to the modulator 211 bit-by-bit and provides a transmitter key-up signal on control line 224.
  • the timing circuit 229 controls the timing of key-up of the transmitter 201, so that a transmission burst is transmitted at a selected time.
  • RSSI line 212 provides logic unit 220 with values of
  • error decoding circuit 213 performs error correction and optionally provides a bit error rate indication to logic unit
  • processor 230 Corrected data is passed to the processor 230 for further processing. Where logic unit 220 is unable to verify a burst as validly received, the processor 230 is informed. Where a burst is not validly received, processor 230 generates a NACK response, which is sent via logic unit 220, modulator 211 and transmitter 201.
  • the processor 230 recombined packet fragments and packets for passing on to upper layers of the protocol, for presentation at the operator interface 233 or for outputting at the data terminal 22.
  • the logic unit 220 performs physical layer processing, but higher layer processing can also be performed by logic unit 220, or physical layer processing (such as the error decoding function of error decoding circuit 213) can be performed by the processor 230. These details are not significant.
  • duplexer 203 an antenna switch can be used, allowing alternative receive and transmit modes, even on the same frequency.
  • Logic unit 220 controls synthesizer 205 via control bus 226 to select appropriate frequencies for transmission and reception depending on the particular frequencies of the system and the modulation scheme and other aspects of the physical layer.
  • the base station transceiver 12 with its controller 13 operates to transmit bursts to many remote units.
  • a dotting sequence 80 is not necessary. In other respects the circuit-level operation is not significantly different from the operation of a remote unit. From time to time the controller 13 generates a burst length parameter responsive to the RSSI on line 15 or responsive to a bit error rate or some other indicator or combination of indications of channel quality and sends this in a special message to all remote units. When receiving, the base station transceiver 12 with its controller 13 operates to receive bursts from many remote units.
  • a method for communicating data in packets from a first radio unit 20 to a second radio unit 12, over a radio communications channel comprising, at the first unit 20: formatting data for transmission into first blocks (e.g. blocks 83-86) of data with error coding to provide error coded data; formatting the first blocks of data into transmission bursts 88 or 125-130 with a first ratio of burst level overhead signaling to error coded data (e.g. data 81 in the case of CDPD and the ack/request in time slot group 130 or the burst 126 in the case of GPRS); transmitting the first blocks of data to the second radio unit 12; measuring, e.g.
  • the measuring of the change in quality takes place at the second radio unit 12 and is communicated to the first radio unit 20, for example in the form of a maximum block parameter, but it will be understood that the measuring of change in quality can take place at the first radio unit 20.
  • the ratio of data to burst level overhead signaling can be maximized for given channel conditions and can be made dynamic according to channel quality.

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  • Engineering & Computer Science (AREA)
  • Quality & Reliability (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

On peut communiquer des données par l'intermédiaire d'un canal de communication, tel qu'un canal CDPD ou GSM, en formatant les données en vue de leur transmission en blocs (83-86) de données avec codage des erreurs en formatant ces blocs de données en rafales de transmission (par exemple rafale 88) avec signalisation aérienne du niveau des rafales, en mesurant les variations de la qualité, par exemple RSSI, du canal de communication et en ajustant la proportion des blocs de données sur la signalisation aérienne du niveau des rafales, en fonction des variations de qualité du canal, en vue d'accroître le débit lorsque la qualité du canal est bonne et en vue de renforcer la communication lorsque la qualité du canal n'est pas très bonne.
PCT/US1998/016152 1997-10-02 1998-07-31 Procede et appareil de communication de donnees pour accroitre le debit sur la base de la qualite du canal de communication WO1999018685A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU87665/98A AU8766598A (en) 1997-10-02 1998-07-31 Data communication method and apparatus for increasing throughput based on quality of communications channel

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US94283197A 1997-10-02 1997-10-02
US08/942,831 1997-10-02

Publications (1)

Publication Number Publication Date
WO1999018685A1 true WO1999018685A1 (fr) 1999-04-15

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AU (1) AU8766598A (fr)
FR (1) FR2769447A1 (fr)
WO (1) WO1999018685A1 (fr)

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WO2002028001A1 (fr) * 2000-09-27 2002-04-04 Airspan Networks Inc. Transfert de donnees dans un systeme de telecommunications
WO2002033847A3 (fr) * 2000-10-16 2002-07-11 Ericsson Inc Systemes et procedes pour la communication sans fil de donnees amrt par un multiplexage et un codage adaptatifs
WO2002013447A3 (fr) * 2000-07-21 2002-08-29 Aperto Networks Inc Systeme de telecommunication integre (ii) point a multipoint auto-optimisant a parametres multiples/a variables multiples
US6654384B1 (en) 1999-12-30 2003-11-25 Aperto Networks, Inc. Integrated self-optimizing multi-parameter and multi-variable point to multipoint communication system
SG115491A1 (en) * 2001-08-21 2005-10-28 Ntt Docomo Inc Radio communication system, communication terminal, and method for transmitting burst signals
US7099289B2 (en) 2000-10-11 2006-08-29 Aperto Networks, Inc. Automatic retransmission and error recovery for packet oriented point-to-multipoint communication
US7139251B1 (en) 2001-05-29 2006-11-21 Aperto Networks, Inc. Scheduling for links having changing parameters
WO2007006793A1 (fr) * 2005-07-14 2007-01-18 Piping Hot Networks Limited Optimisation autonome de synchronisation de duplex a repartition dans le temps et seuils de modulation adaptative
GB2435160A (en) * 2006-01-27 2007-08-15 Samsung Electronics Co Ltd A WLAN system which determines the length of frames on the basis of quality of channel
US7349426B2 (en) 1999-12-30 2008-03-25 Aperto Networks, Inc. Integrated, self-optimizing, multi-parameter/multi-variable point-to-multipoint communication system [II]
US8311040B2 (en) 2001-01-16 2012-11-13 Wi-Lan, Inc. Packing source data packets into transporting packets with fragmentation
US8437702B2 (en) 2001-05-14 2013-05-07 Intel Corporation Dynamic channel quality measurement procedure implemented in a wireless digital communication system to prioritize the forwarding of downlink data

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US7206292B2 (en) 1999-12-30 2007-04-17 Aperto Networks, Inc. Integrated self-optimizing multi-parameter and multi-variable point to multipoint communication system
US6654384B1 (en) 1999-12-30 2003-11-25 Aperto Networks, Inc. Integrated self-optimizing multi-parameter and multi-variable point to multipoint communication system
US8867473B2 (en) 1999-12-30 2014-10-21 Wi-Lan, Inc. Integrated self-optimizing multi-parameter and multi-variable point to multipoint communication system
US8432817B2 (en) 1999-12-30 2013-04-30 Wi-Lan, Inc. Integrated self-optimizing multi-parameter and multi-variable point to multipoint communication system
US6992986B2 (en) 1999-12-30 2006-01-31 Aperto Networks, Inc. Integrated self-optimizing multi-parameter and multi-variable point to multipoint communication system
US7366133B1 (en) 1999-12-30 2008-04-29 Aperto Networks, Inc. Integrated, self-optimizing, multi-parameter/multi-variable point-to-multipoint communication system [II]
US7349426B2 (en) 1999-12-30 2008-03-25 Aperto Networks, Inc. Integrated, self-optimizing, multi-parameter/multi-variable point-to-multipoint communication system [II]
WO2002013447A3 (fr) * 2000-07-21 2002-08-29 Aperto Networks Inc Systeme de telecommunication integre (ii) point a multipoint auto-optimisant a parametres multiples/a variables multiples
US7177320B2 (en) 2000-09-27 2007-02-13 Airspan Networks Inc. Transfer of data in a telecommunications system
WO2002028001A1 (fr) * 2000-09-27 2002-04-04 Airspan Networks Inc. Transfert de donnees dans un systeme de telecommunications
US7099289B2 (en) 2000-10-11 2006-08-29 Aperto Networks, Inc. Automatic retransmission and error recovery for packet oriented point-to-multipoint communication
US8023420B2 (en) 2000-10-11 2011-09-20 Wi-Lan, Inc. Automatic retransmission and error recovery for packet oriented point-to-multipoint communication
US6873613B1 (en) 2000-10-16 2005-03-29 Ericsson Inc. Methods for wirelessly communicating time division multiple access (TDMA) data using adaptive multiplexing and coding
WO2002033847A3 (fr) * 2000-10-16 2002-07-11 Ericsson Inc Systemes et procedes pour la communication sans fil de donnees amrt par un multiplexage et un codage adaptatifs
US9374733B2 (en) 2001-01-16 2016-06-21 Wi-Lan, Inc. Packing source data packets into transporting packets with fragmentation
US11197290B2 (en) 2001-01-16 2021-12-07 Wi-Lan Inc. Packing source data packets into transporting packets with fragmentation
US10772086B2 (en) 2001-01-16 2020-09-08 Wi-Lan Inc. Packing source data packets into transporting packets with fragmentation
US8311040B2 (en) 2001-01-16 2012-11-13 Wi-Lan, Inc. Packing source data packets into transporting packets with fragmentation
US9119095B2 (en) 2001-01-16 2015-08-25 Wi-Lan, Inc. Packing source data packets into transporting packets with fragmentation
US9253789B2 (en) 2001-05-14 2016-02-02 Intel Corporation Dynamic channel quality measurement procedure implemented in a wireless digital communication system to prioritize the forwarding of downlink data
US8437702B2 (en) 2001-05-14 2013-05-07 Intel Corporation Dynamic channel quality measurement procedure implemented in a wireless digital communication system to prioritize the forwarding of downlink data
US7139251B1 (en) 2001-05-29 2006-11-21 Aperto Networks, Inc. Scheduling for links having changing parameters
SG115491A1 (en) * 2001-08-21 2005-10-28 Ntt Docomo Inc Radio communication system, communication terminal, and method for transmitting burst signals
US7190967B2 (en) 2001-08-21 2007-03-13 Ntt Docomo, Inc. Radio communication system, communication terminal, and method for transmitting burst signals
US7751430B2 (en) 2005-07-14 2010-07-06 Motorola, Inc. Self optimization of time division duplex (TDD) timing and adaptive modulation thresholds
WO2007006793A1 (fr) * 2005-07-14 2007-01-18 Piping Hot Networks Limited Optimisation autonome de synchronisation de duplex a repartition dans le temps et seuils de modulation adaptative
GB2435160A (en) * 2006-01-27 2007-08-15 Samsung Electronics Co Ltd A WLAN system which determines the length of frames on the basis of quality of channel

Also Published As

Publication number Publication date
AU8766598A (en) 1999-04-27
FR2769447A1 (fr) 1999-04-09

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