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
  • H04L1/12—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
  • H04L1/1829—Arrangements specially adapted for the receiver end
  • H04L1/1835—Buffer management
  • H04L1/1845—Combining techniques, e.g. code combining
• • 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
• • 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
  • H04L1/0036—Systems modifying transmission characteristics according to link quality, e.g. power backoff arrangements specific to the receiver
  • H04L1/0038—Blind format detection
• • 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
  • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
  • H04L1/0045—Arrangements at the receiver end
  • H04L1/0046—Code rate detection or code type detection
• • 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
  • H04L1/1812—Hybrid protocols; Hybrid automatic repeat request [HARQ]
  • H04L1/1819—Hybrid protocols; Hybrid automatic repeat request [HARQ] with retransmission of additional or different redundancy

Definitions

• the present invention relates to transmissions and retransmissions in a communications system, and more especially it relates to a cellular mobile radio system, particularly to a Universal Mobile Telecommunications System, UMTS or WCDMA system.
• Transmission and retransmission of data to or from a mobile station, MS, or user equipment, UE, is previously known. It is also known to use medium access control and radio link control layers of a UMTS protocol structure in acknowledged mode for dedicated channels .
• ARQ automatic repeat request
• a radio network controller is understood as a network element including a radio resource controller.
• Node B is a logical node responsible for radio transmission/reception in one or more cells to/from a User Equipment.
• a base station, BS is a physical entity representing Node B.
• Medium access control, MAC, and radio link control, RLC is used within radio communications systems like General Packet Radio Services, GPRS, and UMTS.
• Node B 1 and Node B 2 of a ra- dio communications system are logical nodes responsible for radio transmission/reception in one or more cells to/from the User Equipment UE .
• BS 1 and BS 2 are physical entities representing Node B 1 and Node B 2 respectively.
• Node B 1 and Node B 2 terminate the air interface, called Uu inter- face within UMTS, between UE and respective Node B towards the radio network controller RNC.
• RNC radio network controller
• Iub interface the interface between a Node B and an RNC is called Iub interface.
• 3GPP 3 rd Generation Partnership Project
• 3GPP Technical Speci fication Group Radio Access Network
• Physical Layer Proce- dures 3G TS 25. 301 v3 . 6. 0 , France, September 2000
• 3GPP 3 rd Generation Partnership Project
• Layer 2, L2 , and layer 3, L3 are divided into Control and User Planes.
• Layer 2 consists of two sub-layers, RLC and MAC, for the Control Plane and four sub-layers, BMC, PDCP, RLC and MAC, for the User Plane.
• BMC, PDCP, RLC and MAC denote Broadcast/Multicast Control, Packet Data Convergence Protocol, Radio Link Control and Medium Access Control respectively.
• FIG. 2 illustrates a simplified UMTS layers 1 and 2 protocol structure for a Uu Stratum, UuS, or Radio Stratum, between a user equipment UE and a Universal Terrestrial Radio Access Network, UTRAN.
• Radio Access Bearers, RABs make available radio resources (and services) to user applications.
• RLC Radio Link Control
• RLC entity There is one RLC entity for each RAB.
• RABs are mapped onto respective logical channels.
• a Medium Access Control, MAC entity receives data transmitted in the logical channels and further maps logical channels onto a set of transport channels.
• MAC should support service multiplexing e.g. for RLC services to be mapped on the same transport channel.
• identification of multi- plexing is contained in the MAC protocol control information.
• Transport channels are finally mapped to a single physical channel which has a total bandwidth allocated to it by the network.
• a physical channel is defined by code, frequency and, in the uplink, relative phase (I/Q) .
• time division duplex mode a physical channel is defined by code, frequency, and time- slot.
• the DSCH e.g., is mapped onto one or several physical channels such that a specified part of the downlink re- sources is employed.
• the Ll layer is responsible for error detection on transport channels and indication to higher layer, FEC encoding/decoding and in- terleaving/deinterleaving of transport channels.
• PDCP provides mapping between Network PDUs (Protocol Data
• PDCP compresses and decompresses redun- dant Network PDU control information (header compression and decompression) .
• BMC For transmissions on point-to-multipoint logical channels, BMC stores at UTRAN-side Broadcast Messages received from an RNC, calculates the required transmission rate and requests for the appropriate channel resources . . It receives scheduling information from the RNC, and generates schedule messages. For transmission, the messages are mapped on a point-to-multipoint logical channel. At the UE side, BMC evaluates the schedule messages and deliver Broadcast Messages to upper layer in the UE.
• 3G TS 25.301 also describes protocol termination, i.e. in which node of UTRAN the radio interface protocols are terminated, or equivalently, where within UTRAN the respective protocol services are accessible.
• 3GPP 3 rd Generation Partnership Project
• 3GPP Technical Speci fication Group Radio Access Network, Physical Layer Procedures, 3G TS 25. 322 v3 . 5. 0 , France, December 2000, specifies the RLC protocol.
• the RLC layer provides three serv- ices to the higher layers:
• BCH Broadcast Channel
• a radio frame is a processing duration, which consists of 15 slots.
• the length of a radio frame corresponds to 38400 chips.
• a slot is a duration, which consists of fields containing bits.
• the length of a slot corresponds to 2560 chips.
• the specification defines two uplink dedicated physical channels :
• uplink Dedicated Physical Control Channel uplink DPCCH.
• the uplink DPDCH is used to carry the DCH transport channel . There may be zero, one, or several uplink DPDCHs on each radio link.
• the uplink DPCCH is used to carry control information generated at Layer 1 .
• the Layer 1 control information consists of known pilot bits to support channel estimation for coherent detection, transmi t power-control (TPC) commands, feedback information (FBI) , and an optional transport- format combination indicator (TFCI) .
• the transport- format combination indicator informs the receiver about the instantaneous transport format combination of the transport channels mapped to the simul taneously transmi tted uplink DPDCH radio frame . There is one and only one uplink DPCCH on each radio link. "
• Figure 3 illustrates the frame structure for uplink DPDCH and DPCCH.
• DPDCH and DPCCH are time division multiplexed.
• the frame structure of uplink data and control parts associated with CPCH is similar to that of uplink DPDCH and uplink DPCCH respectively.
• 3GPP Technical Speci- fication Group Radio Access Network, Mul tiplexing and channel coding (FDD) , 3G TS 25. 212 v5. 0. 0 , France, March 2002, describes the characteristics of the Layer 1 multiplexing and channel coding in the FDD mode of UTRA.
• Section 4.3 describes transport format detection.
• 3GPP 3 rd Generation Partnership Project
• RRC Radio Resource Control
• Section 10.3.5.11 describes in tabular format Transport Channel, TrCH, Information Elements of RRC messages related to semi-static transport format information, TFI, including transmission time interval, TTI .
• TTI is the duration of data over which coding and interleaving is per- formed for a certain transport channel . According to the 3GPP technical specification, TTI is one of 10, 20, 40 and 80 ms .
• Section 10.3.5.80 describes transport format combination, TFC, control duration, defining a period in multiples of 10 ms frames for which the defined TFC sub-set is to be applied.
• Section 10.3.6.81 describes a Transport Format Combination Indicator, TFCI, combining indicator, indicating by TRUE or FALSE whether a part of TFCI, TFCI2 , should be softly combined with other TFCI2 parts of the combining set.
• Section 10.3.6 describes corresponding Physical Channel, PhyCH or PhCH, Information Elements as applicable.
• WCDMA and UMTS presently only supports TTIs of 10, 20, 40 or 80 ms. According to prior art, one TFCI is normally transmitted in each radio frame, i.e. once every 10 ms .
• Delay problems have been identified for existing channel structure in some situations, e.g. communications according to TCP (Transmission Control Protocol) , at high data rates, particularly in the uplink between UE and Node B.
• TCP Transmission Control Protocol
• a further object is to introduce a channel structure allow- ing for interchanging transmissions of radio frame structured data and sub-frame structured data, respectively.
• Figure 1 shows communication, according to the invention, between a UE and a base station involved in a connection between an RNC and the UE .
• Figure 2 displays a layered protocol structure, according to prior art, in a radio communications system.
• Figure 3 illustrates the frame structure for uplink DPDCH and DPCCH, according to prior art.
• Figure 4 shows a preferred frame and sub-frame channel structure for DPDCH and DPCCH, according to the invention.
• Figure 6 shows a flow chart schematically illustrating detection according to a preferred embodiment of the invention.
• Figure 8 schematically illustrates MAC and RLC protocol layers in a multilayer protocol structure.
• WCDMA and UMTS presently only supports TTIs of 10, 20, 40 or 80 ms .
• one TFCI is transmitted in each radio frame, i.e. once every 10 ms .
• particular radio frame TFCI is also referred to as TFCI r f, to distinguish from particular sub-frame TFCI, referred to as TFCIsf-
• TTIs being integer multiples of 10 ms
• the same TFCI content is repeated in the multiple radio frames for additional redundancy to be combined for in- creased reliability.
• a plurality of transport channels are generally multiplexed and coded into a Coded Composite Transport Channel, CCTrCH, for transmission on the physical channel. There is one TFCI for each CCTrCH.
• TTI is fixed for a particular TrCH.
• TCP Transmission Control Protocol
• a solution to the problem to be applied in e.g. UMTS or a WCDMA system should be back- ward compatible with equipment operating according to existing specifications. Such backward compatibility will provide for soft handover possibility also between Nodes B operating according to different releases and non-increased power requirement on UE at cell border. Further, for prior art 3GPP specifications there is a restriction from e.g. existing Release '99 as there is no means to indicate different TTIs for a TrCH.
• PAR peak-to-average power ratio
• a further problem is RRC signaling according to prior art requiring 40 ms TTI.
• One rationale for this interval is strict power budgets of UE to be kept also at cell border.
• the above mentioned problems are solved by introducing an alternative transmission time interval, and a corresponding sub-frame, shorter than that existing, requiring a new structure on the physical chan- nel.
• a channel structure is superimposed on an existing channel structure to allow use of shorter TTIs on existing data channels, DPDCHs, without violating existing data channel TTI structure and without increasing PAR.
• Figure 4 illustrates a preferred channel structure according to the invention.
• a radio frame according to the preferred embodiment of the invention is divided into an integer number of equally sized sub-frames, each sub-frame comprising an integer number of slots.
• Exemplary 15 slots per frame in accordance with 3GPP technical specifications, can be factored, giving three possible sub- frame sizes of 3 or 5 slots respectively.
• DPDCH and DPCCH are divided into the sub-frame structure. With preferred 5 sub-frames there are consequently 5 data blocks, «Data #0», «Data #1», «Data #2», «Data #3», «Data #4».
• TFCI of the sub-frame channel structure is included in every transmitted sub-frame of DPCCH.
• TFCIsf there is only needed to transmit TFCI S f, at TFCIsf changes.
• the sub-frame channel structure allows for at least one TFCI s f in each sub-frame, «TFCI sf #0», «TFCI sf #1», «TFCI sf #2», «TFCI sf #3», «TFCI S f #4».
• the blind TTI detection according to the invention may be used with known technologies of TFCI detection according to 3GPP technical specification.
• the TFCI field of the slot structure comprises two bits per slot.
• the TFCI rf bits are FEC encoded such that the 30 bits represent 10 information bits. I.e., 1024 transport format combinations can be represented by TFCIrf.
• TFCI ⁇ f would comprise 6 bits, given that two bits of each slot carry TFCI bits.
• these TFCI bits would represent at most 64 transport format combinations. With redundancy included, typically 4 or 8 transport format combinations can be represented.
• Figure 6 shows a flow chart schematically illustrating detection according to a preferred embodiment of the invention.
• the receiver initially anticipates received TFCI field comprises TFCIsf data and detects, by decoding of the first slots on DPDCH corresponding to a first sub-frame, if any, whether or not there is a sub-frame of the received trans- mission.
• Each data channel sub-frame is protected by forward error control coding. This enables the receiver to correct and/or detect transmission errors. Only some symbol combinations are valid codewords. If a symbol combination is not among the considered correct codewords after decoding a transmission error can be detected. However, if e.g.
• a radio frame codeword not comprising a sub-frame codeword in its first slots, is transmitted this will appear as a transmission subject to transmission errors to a decoder assuming a sub-frame codeword being transmitted.
• This relationship is utilized in the preferred embodiment of the receiver operating according to the flow chart of figure 6 for determining whether or not a sub-frame structure is superimposed on the prior art radio frame structure.
• TTI is greater than one radio frame
• the entire TTI on DPDCH is decoded and forwarded to higher layers prior to halting the process and restarting for next one or more radio frames. Otherwise, no more data is passed to higher layers and the process ends to restart for next one or more radio frames.
• a majority vote on the sub- frame decoding attempts of a received radio frame is deter- mined prior to any decoding attempt of an entire radio frame. If, e.g., 3-5 out of 5 sub-frames are correctly decoded, transmissions are considered according to a sub- frame structure. Depending on false alarm rate and miss rate the vote threshold may be adjusted, e.g. requiring 4-5 correctly decoded sub-frames for considering data sent according to the sub-frame structure.
• the terminal preferably decides whether or not to make use of the sub-frame channel struc- ture according to needs and radio environment. The decision is based on one or more aspects such as available transmit power, transmission activity on channels requiring radio frame channel structure without sub- rame channel structure.
• the distance is increased by using different pilot sequences depending on whether or not a sub-frame structure is imposed or not .
• An alternative solution to this problem is to only allow soft combining of consecutive transmissions for sub-frame TTIs, excluding TTIs being integer multiples of the duration of a radio frame for hybrid ARQ. For reasons of symmetry, buffer savings could alternatively be achieved by only allowing hybrid ARQ for TTIs being integer multiples of a radio frame.
• a drawback of both these alternative solutions is that if retransmission of data need to occur without possibility to retransmit using a sub-frame channel structure, retransmissions cannot be softly combined. This may be the case e.g. due to mobility (some Nodes B may not have implemented a sub-frame channel structure or UE is strictly power limited if moved close to cell border) .
• all Nodes B and UEs of the radio communications system operate according to the invention for outstanding performance.
• the invention can also be used in systems also including Nodes B not operating according to the invention.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Quality & Reliability (AREA)
• Mobile Radio Communication Systems (AREA)
• Detection And Prevention Of Errors In Transmission (AREA)
• Rehabilitation Tools (AREA)

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• 2003
  • 2003-02-17 SE SE0300443A patent/SE0300443D0/xx unknown
• 2004
  • 2004-02-17 EP EP04711787A patent/EP1597856A1/en not_active Withdrawn
  • 2004-02-17 WO PCT/SE2004/000159 patent/WO2004073250A1/en not_active Ceased
  • 2004-02-17 CN CN200480004276.1A patent/CN1751469A/zh active Pending
  • 2004-02-17 KR KR1020057014786A patent/KR20050110630A/ko not_active Withdrawn
  • 2004-02-17 US US10/545,264 patent/US7359359B2/en not_active Expired - Fee Related
  • 2004-02-17 MX MXPA05007487A patent/MXPA05007487A/es unknown
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