WO2016120452A1 - Procédé de multiplexage de canaux physiques de liaison montante pour obtenir une bonne couverture - Google Patents

Procédé de multiplexage de canaux physiques de liaison montante pour obtenir une bonne couverture Download PDF

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Publication number
WO2016120452A1
WO2016120452A1 PCT/EP2016/051925 EP2016051925W WO2016120452A1 WO 2016120452 A1 WO2016120452 A1 WO 2016120452A1 EP 2016051925 W EP2016051925 W EP 2016051925W WO 2016120452 A1 WO2016120452 A1 WO 2016120452A1
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physical
channel
radio terminal
channels
physical channel
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PCT/EP2016/051925
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English (en)
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Erik Larsson
Fredrik OVESJÖ
Gerardo Agni MEDINA ACOSTA
Tomas SVADLING
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Telefonaktiebolaget Lm Ericsson (Publ)
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Publication of WO2016120452A1 publication Critical patent/WO2016120452A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0014—Three-dimensional division
    • H04L5/0016—Time-frequency-code
    • 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
    • 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
    • H04L1/1822—Automatic repetition systems, e.g. Van Duuren systems involving configuration of automatic repeat request [ARQ] with parallel processes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/08—Load balancing or load distribution
    • H04W28/082—Load balancing or load distribution among bearers or channels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0466—Wireless resource allocation based on the type of the allocated resource the resource being a scrambling code

Definitions

  • Embodiments herein relate to a radio access node, a radio terminal and methods therein to achieving good uplink coverage.
  • some embodiments relate to transmitting time-multiplexed signals within a (wide band) code multiplexed radio access. More particularly, some embodiments relate to switching between time multiplexed transmission and (wide band) code multiplexed transmission depending on certain criteria.
  • Wireless devices for communication such as terminals are also known as e.g. User Equipments (UE), mobile terminals, wireless terminals and/or mobile stations.
  • Terminals are enabled to communicate wirelessly in a cellular communications network or wireless communication system, sometimes also referred to as a cellular radio system or cellular networks.
  • the communication may be performed e.g. between two terminals, between a terminal and a regular telephone and/or between a terminal and a server via a Radio Access Network (RAN) and possibly one or more core networks, comprised within the cellular communications network.
  • RAN Radio Access Network
  • Terminals may further be referred to as mobile telephones, cellular telephones, laptops, or surf plates with wireless capability, just to mention some further examples.
  • the terminals in the present context may be, for example, portable, pocket-storable, handheld, computer-comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via the RAN, with another entity, such as another terminal or a server.
  • the cellular communications network covers a geographical area which is divided into cell areas, wherein each cell area being served by a base station, e.g. a Radio Base Station (RBS), which sometimes may be referred to as e.g. "eNB”, “eNodeB”, “NodeB”, “B node”, Base Transceiver Station (BTS), or AP (Access Point), depending on the technology and terminology used.
  • a cell is the geographical area where radio coverage is provided by the base station at a base station site.
  • One base station, situated on the base station site may serve one or several cells.
  • each base station may support one or several communication technologies.
  • the base stations communicate over the air interface operating on radio frequencies with the terminals within range of the base stations.
  • the expression Downlink (DL) is used for the transmission path from the base station to the mobile station.
  • the expression Uplink (UL) is used for the transmission path in the opposite direction i.e. from the mobile station to the base station.
  • Universal Mobile Telecommunications System is a third generation mobile communication system, which evolved from the GSM, and is intended to provide improved mobile communication services based on Wideband Code Division Multiple Access (WCDMA) access technology.
  • UMTS Terrestrial Radio Access Network (UTRAN) is essentially a radio access network using wideband code division multiple access for terminals.
  • a Radio Network Controller is a governing element in the UMTS radio access network and is responsible for controlling the Node Bs that are connected to it.
  • the RNC carries out radio resource management, some of the mobility management functions and is the point where encryption is done before user data is sent to and from the mobile.
  • the RNC connects to a Circuit Switched Core Network through Media Gateway (MGW) and to a SGSN (Serving GPRS Support Node) in a Packet Switched Core Network.
  • MGW Media Gateway
  • SGSN Serving GPRS Support Node
  • EUL Enhanced Uplink
  • HSUPA High-Speed Uplink Packet Access
  • HSUPA supports a short transmission time interval, TTI (2 milliseconds, ms) allowing a rapid adaptation of transmission parameters and a longer TTI for larger cells (10 ms). Further, HSUPA employs a fast hybrid-ARQ with soft combining.
  • These enhancements are implemented in WCDMA through a new transport channel, the Enhanced Dedicated Channel, E-DCH as being specified in 3GPP TS 25.21 1 , current version 12.1 .0.
  • the E-DCH is mapped to a set of uplink channelization codes being referred to as E-DCH Dedicated Physical Data Channel (E- DPDCHs).
  • E- DPDCH E-DCH Dedicated Physical Data Channel
  • E-DPCCH E-DPCCH
  • the WCDMA physical data channels namely E- DPDCH, E-DPCCH and DPCCH are transmitted in a code-multiplexed manner.
  • E-DPDCH is being transmitted with an accompanying E-DPCCH in the same subframe.
  • Ways of improving the uplink coverage may be broadly be classified as:
  • Reducing the rate - Reducing the rate is another fundamental approach of increasing coverage.
  • a lower data rate requires less power for reliable communication.
  • a reduced rate can in general be achieved by several means, for example reducing the information content, employ repetitions or increasing the TTI.
  • EUL two different TTIs are available (2 ms and 10 ms) and a coverage limited device typically employs 10 ms TTI.
  • data is transmitted on a plurality of physical channels from a radio terminal to a radio access node, wherein certain channels are combined by means of time-multiplexing.
  • the combined physical channel is then code-multiplexed together with at least one further physical channel (the combined physical channel is then associated to a first channelization code, and the further physical channel is associated another channelization code).
  • the number of code multiplexed physical channels can be reduced to fewer physical channels.
  • each of the fewer physical channels can be operated at higher power, thus facilitating better coverage.
  • this transmission mode may be regarded as a first mode, and a transmission mode, wherein all the physical channels of the plurality of physical channels are combined by means of code multiplexing may be regarded as second mode.
  • a switching between these modes may be performed, if a certain condition is met, wherein the certain condition is preferably related to an available transmission power.
  • the transmission in good power conditions, can be performed according to the second mode resulting in a minimum delay, and in poor power conditions, the transmission can be performed according to the fist mode resulting in an increased transmission power for each code-multiplexed channel (at the expense of an increased delay).
  • the switching is controlled by the radio terminal based on predetermined criteria and/or on criteria received from the radio access node.
  • the selected physical channels comprise a (dedicated) physical control channel, and an associated (dedicated) physical data channel.
  • the physical control channel may be an E-DCH Dedicated Physical Control Channel, E- DPCCH
  • the physical data channel may be an E-DCH Dedicated Physical Data Channel, E-DPDCH as being specified in above-mentioned 3GPP TS 25.21 1 .
  • the data transmission is associated to HARQ processes, wherein for each HARQ process, a physical control channel transmission is performed in a first subframe, followed by one associated E-DPDCH transmission in a subsequent subframe or a plurality of associated physical data channel transmissions in a plurality of subsequent subframes.
  • the time multiplexing of the two selected channels is performed in a first certain time period, and in a subsequent second time period, the data is simultaneously transmitted on both the selected physical channels and the at least one other physical channel, said physical channels being separated are separated by means of code multiplexing.
  • a radio terminal for transmitting data on a plurality of physical channels to a radio access node, wherein the radio terminal comprises a transceiver, a processor and memory, said memory containing instructions executable by said processor, whereby said radio terminal is operative to providing a combined physical channel by time multiplexing two selected physical channels out of the plurality of physical channels, and transmitting data on the combined physical channel and on at least one further physical channel out of the plurality of channels, wherein the combined physical channel and the at least one other physical channel are separated by means of code multiplexing.
  • a radio access node radio for receiving data on a plurality of physical channels from a radio terminal, wherein the radio access node comprises a receiver adapted for receiving data on a plurality of code multiplexed physical channels, and a de-multiplexer adapted for separating a first physical channel from the plurality of further physical channels by means of code de-multiplexing, wherein the first physical channel is a channel comprising a combination of certain physical signals, and for separating the certain physical channels from each other by means of time de-multiplexing.
  • the present invention also concerns computer programs comprising portions of software codes in order to implement the method as described above when operated by a respective processing unit of appropriate nodes, e.g. a radio terminal or radio base station of a radio access network.
  • the computer program(s) can be stored on a computer readable medium.
  • the computer-readable medium can be a permanent or rewritable memory within the radio terminal or radio base station, or located externally.
  • the respective computer program can be also transferred for example via a cable or a wireless link as a sequence of signals.
  • Fig. 1 shows a principal block diagram depicting exemplary radio
  • Fig. 2 shows principal steps being performed in a radio terminal according to the invention
  • Fig. 3 shows principal steps being performed in a radio access node according to the invention
  • Fig. 4 shows an embodiment illustrating a switching between different
  • Fig. 5 shows dedicated physical channels of an enhanced uplink in a time- multiplexed operation
  • Fig. 6 is a further illustration of Fig. 5,
  • Fig. 7 shows an exemplary block diagram of a radio access node
  • Fig. 8 shows an exemplary block diagram of a radio terminal. Detailed Description
  • Fig. 1 illustrates a radio telecommunications network comprising a radio network controller, RNC 60, radio base stations (or Node Bs) 70 connected to the RNC 60 and radio terminals (or UEs) 80 wirelessly communicating with the radio base stations 70.
  • RNC 60 radio network controller
  • RNC 60 radio base stations
  • Node Bs radio base stations
  • UEs radio terminals
  • Each radio base station covers a certain area 20.
  • the physical channels are established between the UE 80 and the radio base station. According to WCDMA, as discussed above, these physical channels are code multiplexed by means of channelization codes. UL physical channels are directed from radio terminals 80 to the radio base stations.
  • Fig. 2 shows principal steps being performed in a radio terminal
  • a combined physical channel is established by time multiplexing two selected UL physical channels.
  • a code multiplexing is performed of the combined physical channel and at least one further UL physical channel.
  • Fig. 3 shows principal steps being performed in a radio base station
  • a first step 310 data is received on a plurality of code multiplexed UL physical channels.
  • a code de-multiplexing is performed to separate the combined physical channel from the at least one further physical channel.
  • a time de-multiplexing is performed to separate the combined physical channels.
  • High speed packet access comprises the following uplink physical channels being transmitted in a code-multiplexed manner:
  • DPCCH carries pilot bits and TPC bits (FBI and TFCI are considered unnecessary for an SDT device).
  • the TPC bits are used to power control the downlink (F-DPCH) and the pilot bits are required for channel estimation purposes. Both the TPC bits and the pilot bits will be needed for coverage limited SDT applications.
  • the pilot bits will, however, be of particular importance, since the more pilot bits, the less power needs to be spent on DPCCH for accurate enough channel estimation. Hence, maximizing the number of pilot bits in the DPCCH slot format is preferred.
  • E-DPCCH carries control information related to the E-DPDCH.
  • the information carried by the E-DPCCH includes a Retransmission Sequence Number, RSN, (covering 2 bits) that indicates a Hybrid Automatic Repeat Request (HARQ) transmission number to the network, a Happy Bit used by a UE to indicate if the UE needs more resources, or more specifically, could benefit from a higher grant in the UL to transmit pending data by setting this bit to "Unhappy,” and an Enhanced-Transmit Format Combination Indicator, E-TFCI, of the current E-DPDCH transmission (covering 7 bits).
  • RSN Retransmission Sequence Number
  • HARQ Hybrid Automatic Repeat Request
  • E-TFCI Enhanced-Transmit Format Combination Indicator
  • These bits are coded with a (30, 10) second order Reed-Muller code and uses a spreading factor of 256. For 10 ms TTI, five times repetition is employed. For coverage limited SDT applications, this information may be restricted.
  • the number of transport block sizes may be significantly reduced or even fixed to one value and/or the happy bit may be removed.
  • the RSN can be used by the decoder to know the redundancy version in incremental redundancy coding, but in general this can be deduced without the RSN due to the synchronous and non-adaptive HARQ procedure used in the uplink.
  • restricting operation to chase combining would, from a coding point of view, mean that the RSN could be reduced to a 1 bit 'new data indicator' (however, the main reason why the RSN consists of two bits instead of one bit is to help identifying signalling error cases in soft handover, SHO, operation).
  • E-DPDCH carries data and different rates are supported via code multiplexing, different coding rates, different modulation schemes, and different spreading factors.
  • small transport block sizes e.g. 120 bits
  • the number of possible transport block sizes may be significantly reduced or even fixed to one value.
  • HS-DPCCH carries DL related feedback that is needed when HSPA is configured.
  • the HS-DPCCH consists of ACK/NACK and CQI/PCI information.
  • the HS-DPCCH can become very costly in terms of power unless very many repetitions are used. Current specifications do not allow more than four repetitions and extending the number of repetitions will impact various system aspects, such as imposing scheduler restrictions and delays.
  • An alternative of employing repetitions could be to remove the channel completely for coverage limited operation. This can be compared to CELL-FACH where it is not possible for the UE to transmit the HS-DPCCH in the uplink.
  • the Node B needs to blindly decide whether to schedule a retransmission and an estimate of the supported data rate can be made from UE measured CPICH power provided by the RNC over the lub frame protocol.
  • a potential enhancement could be to include a limited CQI report in another uplink physical channel.
  • some of the E-TFCI bits in the E-DPCCH can be used to signal a limited set of CQI values.
  • a similar approach could be envisioned for ACK/NACK information, but one complication is that HS-DPCCH is not time-synchronized with UL DPCCH, which could affect the DL HARQ timing.
  • the UL physical channels being time multiplex are E-DPDCH and E- DPCCH.
  • the at least one further UL physical channel may be the DPCCH.
  • WCDMA like most other cellular systems, provides several states:
  • the lowest energy and resource consumption is achieved when the UE is in one of the two paging states specified for WCDMA, namely CELL_PCH and URA_PCH. In these states, the UE sleeps and only occasionally wakes up to check for paging messages.
  • CELL_FACH the UE can transmit small amounts of data as part of the random-access procedure.
  • the UE also monitors common downlink channels for small amounts of user data and RRC signaling from the network.
  • the high transmission activity state is known as CELL DCH. In this state, the UE can use HS-DSCH (High Speed Downlink Shared Channel) and E-DCH for exchanging data with the network.
  • HS-DSCH High Speed Downlink Shared Channel
  • 3GPP has enhanced the functionality available to the UE by allowing HS-DSCH and E-DCH to be used also in CELL FACH.
  • EUL in CELL_FACH consists basically of three stages. First the UE acquires the necessary information to initiate operation of EUL in CELL_FACH via system broadcast; for example, the preamble signatures used for EUL-FACH and common E-DCH parameters. Second the UE performs random access on the Physical Random Access Channel, PRACH, to gain access to the network. In this phase the UE sends preambles with increasing power until the network acknowledges that it has detected the UE by sending a response on the Acquisition Indicator Channel, AICH. Then, the UE can start transmitting on common E-DCH very much as in CELL_DCH. EUL in CELL_FACH works the same way as EUL in CELL_DCH except that soft-handover is not supported. Hence, embodiments of the invention cover both for EUL in CELL_FACH and EUL in CELL DCH.
  • PRACH Physical Random Access Channel
  • the powers of the uplink physical channels are set relative the power of DPCCH by means of gain factors (ed for E- DPCCH, ec for E-DPCCH and hs for HS-DPCCH). As discussed above, it is recommended to divide the available power efficiently between the UL physical channels, especially when being coverage limited and thereby transmitting at a maximum power or close to the maximum power.
  • DPCCH serves as the pilot channel in the uplink, meaning that detection and demodulation of other UL physical channels rely on channel estimates calculated based on pilot symbols from the DPCCH.
  • the pilots on the DPCCH are also used for synchronization purposes and for the searcher to find channel tap delays.
  • Increasing the power related to E-DPDCH or E- DPCCH operating at the expense of DPCCH power may affect the channel estimation quality resulting in poor demodulation performance, as DPCCH, amongst others, is needed for channel estimation.
  • increasing the number of E-DPDCH transmissions reduces the available power for each E-DPDCH transmission, and control channel overhead may become even more dominant.
  • a number of code multiplexed channels is reduced in order to enabling higher power consumption per channel.
  • at least two of the channels are separated in time, i.e. time multiplexed (instead of being separated by code from each other).
  • E-DPCCH and E-DPDCH transmissions are time multiplexed, since E-DPCCH can have a significant power cost in scenarios where multiple E-DPDCH transmissions with small transport block sizes and soft combining are required.
  • an E-DPCCH transmission is performed in a first subframe, followed by one associated E-DPDCH transmission or a plurality of associated E-DPDCH transmissions in subsequent subframes corresponding to the specific HARQ process.
  • a bundled E-DPDCH transmission is being referred to as one or more subsequent E-DPDCH transmissions with one associated control channel (E-DPCCH).
  • the E-DPDCH transmissions have similar attributes (e.g. transport block, code-rate, coded bits) or potentially a deterministic change of attributes between transmission attempts (e.g. the redundancy version may change in a deterministic manner if incremental redundancy is configured).
  • each bundled transmission is jointly acknowledged (ACK/NACK sent on E-HICH) when the complete bundled transmission is received and processed.
  • Negatively acknowledged transmissions can then be retransmitted, where the retransmission may follow the same transmission structure as the initial transmission, i.e. first E-DPCCH is sent with the RSN increased, and then a number of bundled E- DPDCH transmissions.
  • An operation is illustrated in Fig. 5, exemplarily showing four HARQ processes, namely HARQ process one 501 , HARQ process two 502, HARQ process three 503 and HARQ process four 504, exemplarily using a bundle length of 1 , 2, 2, and 3, respectively.
  • HARQ process two 502 shall be considered.
  • the E-DPCCH is transmitted carrying control information (e.g. E-TFCI, and RSN) associated with the bundled E-DPDCH transmission to follow.
  • control information e.g. E-TFCI, and RSN
  • the associated bundled E-DPDCH transmissions takes place.
  • the Node B has received the second E-DPDCH, the bundled transmission is acknowledged (ACK/NACK/DTX) via the Enhanced DCH Hybrid ARQ Indicator Channel, E-HICH.
  • the number of E-DPDCH transmissions associated with one E-DPCCH may be chosen in view of a trade-off between delay/latency, control channel overhead, and flexibility. Different processes may use different bundling patterns. A special case would be to always assume a bundle-length of one, i.e. each E-DPCCH transmission would be followed by only one E-DPDCH transmission. Yet another special case would be to configure a large enough bundle-length and not use any retransmissions. This would correspond to operating with a fixed number of retransmissions where the E-DPCCH is only sent for an initial transmission.
  • each bundled transmission is acknowledged (via E-HICH), e.g. according to existing mechanisms. This means that if decoding of a bundled E-DPDCH transmission is successful (by means of cyclic redundancy code, CRC, checking), a positive acknowledgment (ACK) is sent over E-HICH; otherwise a negative acknowledgment (NACK) is sent.
  • E-HICH e.g. cyclic redundancy code
  • intermediate E-DPDCH transmissions are not acknowledged, i.e. an acknowledgement is only sent once the whole bundled transmission is received such that the acknowledgment corresponds to the joint decoding of all bundled E-DPDCHs.
  • each of the E-DPDCH transmissions may be acknowledged. This would allow stopping a transmission of the bundled frame before all bundled E-DPDCHs are sent, and immediately sending a new E-DPCCH to start using a HARQ process for new data. Such embodiment may facilitate a more efficient use of available resources and may increase the performance.
  • the timing of the transmission structure is being kept, i.e. the next E- DPCCH would not be sent until all bundled E-DPDCH subframes have passed.
  • a benefit of such method would then be that the UE can DTX parts of the bundled E- DPDCH transmission if the Node B manages to successfully decode the transmission before all bundled transmissions have occurred and thereby saving power. It could also be beneficial to always send the final bundled acknowledgment even though an early ACK was sent. If early acknowledgments are allowed, the information sent over E-HICH may probably be ACK or DTX (as a sending a NACK would not make sense unless it is the final acknowledgment covering the joint bundled E-DPDCH).
  • E-HICH acknowledgment handling concerning the E- DPCCH transmission.
  • no acknowledgment is sent corresponding to an E-DPCCH transmission.
  • the E-DPCCH transmission is acknowledged, i.e. if the Node B detects an E-DPCCH, then a positive acknowledgment is sent.
  • NACK or DTX nothing
  • Sending NACK can be rather resource expensive since most of the time the Node B does not detect an E-DPCCH transmission if no data is being sent and thus the UE has not performed any corresponding E-DPCCH transmission.
  • An alternative is thus to use ACK and DTX.
  • E-DPCCH transmissions could help identifying signalling error cases. For example, if the UE does not receive an ACK, it could re-send the E-DPCCH instead of initiating the E-DPDCH transmission(s). Sending the E-DPDCH if the Node B has not detected the E-DPCCH would be a waste since the Node B does not expect an E-DPDCH (the Node B is looking for an E-DPCCH and might not even despread the E-DPDCH) and would not know the E-TFCI (TBS, codes, etc.) or RSN (new transmission or retransmission).
  • E-HICH signalling might fail, e.g.
  • the UE interprets an ACK as a NACK or DTX as ACK.
  • An ACK interpreted as NACK would mean that the UE thinks the Node B has not detected the E-DPCCH even though it in fact has detected it. The UE would then re-send the E-DPCCH.
  • the Node B should always listen for an E- DPCCH, i.e. even if the Node B has positively acknowledged the E-DPCCH and expects an E-DPDCH, it might in fact be an E-DPCCH that is transmitted. If possible the Node B should then increase the power of the E-HICH and re-send the ACK.
  • a DTX interpreted as ACK would mean that the UE thinks that the Node B has received the E- DPCCH and the UE would send E-DPDCH in the next associated subframe. Since the Node B has not detected an E-DPCCH it will still be searching for an E-DPCCH and will not be able to decode the bundled E-DPDCH transmission and a retransmission will occur.
  • a transmission mode control is provided to switch between selected code-multiplexed or time-multiplexed physical UL channels (e.g. E-DPCCH and E-DPDCH) operation. It may be preferred to use the "normal" operation with code-multiplexed UL channels as much as possible and only switch to time-multiplexing when becoming coverage limited. Code-multiplexing has the benefit of being more efficient in terms of delay/latency, while time-multiplexing utilizes the available power in a more focused manner.
  • code-multiplexed or time-multiplexed physical UL channels e.g. E-DPCCH and E-DPDCH
  • a first step 410 it is detected, if the UE gets coverage limited.
  • second step 420 is performed in that selected physical channels are time multiplexed.
  • third step 430 is performed to perform code multiplexing for all physical channels.
  • One approach would be to re-configure (via higher layer signalling) from code- multiplexing to time-multiplexing when becoming coverage limited. However, it may be difficult (non-robust) to re-configure once the UE has become power limited since the reliability of signalling decreases significantly, thus potentially resulting in an unpredictable behavior.
  • Another approach is to switch to time-multiplexed operation when the serving grant becomes too small, e.g. below a first (e.g. network configured) threshold (and switching back when the serving grant gets sufficiently big, e.g. above a second threshold (the second threshold may be equal or greater than the first threshold).
  • the switching may also or alternatively be based on an expected needed transmission power for the transmissions and an available power headroom, such that when the UE estimates that it cannot transmit the minimum transport block size at a suitable power level when the E-DPCCH is present in the same subframe, it switches to using time-multiplexing instead.
  • a new E-DCH transport block size table may be introduced, wherein a part of the entries correspond to time-multiplexed operation and the other part of the entries correspond to code-multiplexed operation.
  • E-DCH transport block size tables for 2 and 10 ms TTIs. These tables provide a mapping between E-TFCI and transport block size. Given the current structure of E-DPCCH where the E-TFCI corresponds to 7 information bits, the maximum number of E-TFCIs that can be signalled is 128 (E-TFCI value 0 to 127). Hence, it is possible to add yet another E-DCH transport block table where some entries correspond to time-multiplexed operation. This could be achieved in various ways, including, but not limited to:
  • E-TFCI entries 1 to n correspond to time-multiplexed operation with a default transport block size (either hardcoded or network configured) and different bundling lengths (i.e. the number of E-DPDCH transmissions associated with one bundled transmission).
  • E-TFCI 1 corresponds to n E-DPDCH transmissions within a bundled transmission
  • E-TFCI 2 corresponds to n-1 E- DPDCH transmissions within a bundled transmission
  • E-TFCI n corresponds to 1 E-DPDCH transmissions within a bundled transmission.
  • the rest of the E- TFCI entries n+1 , 127 (and 0 which typically is used for special SRB transmissions) may correspond to 'normal' code-multiplexed operation. A special case could be to only configure/allow one bundle-length.
  • Different HARQ processes may potentially use different bundling lengths.
  • Fig. 6 thereto shows an example essentially similar to Fig. 5, wherein E-TFCIs 1 to 3 correspond to time-multiplexed operation using a default 'coverage limited' TBS (e.g. 120) and three, two or one bundled E-DPDCH transmissions, respectively.
  • HARQ process one uses E-TFCI 3 meaning that each E-DPCCH is associated with one E-DPDCH transmission
  • HARQ processes two and three E- TFCI 2 meaning that each E-DPCCH is associated with two E-DPDCH transmissions
  • HARQ process four uses E-TFCI 1 meaning that each E-DPCCH is associated with three E-DPDCH transmissions.
  • E-TFCIs 1 to 3 are associated with time-multiplexed operation, whereas other E-TFCIs can be associated with ordinary code-multiplexed operation.
  • E-TFCI 2 is chosen, then time-multiplexed operation with two bundled E-DPDCHs is employed.
  • a SDT device would then be configured with the special table and depending on the currently used E-TFCI, either code or time multiplexing is used.
  • the current HARQ process structure and HARQ ACK/NACK timing are kept with proposed solutions, and the HARQ operation can still be synchronous and non-adaptive.
  • the MAC protocol needs, however, to keep track of whether the transmission is an E-DPCCH or an E-DPDCH and whether transmission info should be updated or not.
  • the information includes, but is not limited to, acknowledgment info received via E-HICH, the RSN counter, etc.
  • special rules may be added in the MAC specifications.
  • DPCCH consumes power that, if put on E-DPCCH or E-DPDCH could increase coverage.
  • DPCCH is required for channel estimation purposes; in a worst case, nothing may be able to be transmitted, if the DPCCH quality is not good enough.
  • DPCCH is to be continuously transmitted (note however that discontinuous DPCCH transmission is allowed if CPC is configured but only when no other UL physical channels are transmitted).
  • the radio channel may change slowly. According to embodiments, in such situations DPCCH transmissions are performed discontinuously and channel estimation relies on previous channel estimates when the DPCCH is not available.
  • the receiver may employ time- averaging wherein information from past, current and even predictions of future slots are taken into consideration when forming the channel estimate for the current slot.
  • DTX DPCCH based on a known (by both UE and network) pattern in order to focus all available power on either E-DPCCH or E-DPDCH.
  • the pattern can be standardized, configured by the network or depend on the UE speed (Doppler spread).
  • the current HARQ structure is kept.
  • the HARQ process structure remains such that transmissions associated with a specific process cannot be transmitted in other processes.
  • Another alternative for enabling time- multiplexing is to increase the number of HARQ processes and bundle several consecutive HARQ processes. For example, assume that 8 HARQ processes are configured for 10 ms TTI. Then processes ⁇ 1 ,2 ⁇ , ⁇ 3,4 ⁇ , ⁇ 5,6 ⁇ and ⁇ 7,8 ⁇ could be bundled (in total 4 bundled processes). In process 1 the E-DPDCH associated with the bundled process ⁇ 1 ,2 ⁇ is sent, and in process 2 the E-DPDCH associated with the bundled processes ⁇ 3,4 ⁇ is sent, and similar for the other bundled processes.
  • this approach might have a more or less significant impact on the existing HARQ structure, e.g. the round-trip-time.
  • Fig. 7 is a block diagram of a base station 70 as depicted in Fig. 1 .
  • the base station may include a first interface or transceiver circuit 710 (also referred to as a transceiver) configured to provide radio communications with a plurality of UEs, and the second interface or network interface circuit 740 (also referred to as a network interface) configured to provide communications with the RNC 60, and a processor circuit 720 (also referred to as a processor) coupled to the transceiver circuit 710 and the network interface circuit 740, and a memory circuit 730 (also referred to as a memory) coupled to the processor 720.
  • the memory 730 may include computer readable program code that when executed by the processor 720 causes the processor circuit to perform base station operations.
  • the computer readable program may be downloaded entirely or in parts from a computer-readable medium into the memory of the UE or the base station respectively.
  • the computer-readable medium may include an electronic, magnetic, optical, electromagnetic, or semiconductor data storage system, apparatus, or device. More specific examples of the computer-readable medium would include the following: a portable computer diskette, a random access memory (RAM) circuit, a read-only memory (ROM) circuit, an erasable programmable read-only memory (EPROM or Flash memory) circuit, a portable compact disc read-only memory (CD-ROM), and a portable digital video disc read-only memory (DVD/BlueRay).
  • Fig. 8 is a block diagram illustrating elements of the user equipment UE 80 of Fig. 2.
  • the UE 80 may include a transceiver or interface circuit 810 (also referred to as a transceiver) configured to provide radio communications with the base station 70, a processor circuit 820 (also referred to as a processor) coupled to the transceiver circuit, and a memory circuit (also referred to as a memory) 830 coupled to the processor circuit.
  • the memory 830 may include computer readable program code that when executed by the processor circuit 820 causes the processor to perform UE operations according to embodiments disclosed herein.
  • the processor 820 may be defined to include memory so that the memory 830 may not be separately provided.

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

Abstract

La présente invention concerne un procédé de transmission de données sur une pluralité de canaux physiques depuis un terminal radio vers un nœud d'accès radio, comprenant les étapes consistant à : fournir un canal physique combiné par multiplexage temporel de deux canaux physiques sélectionnés parmi la pluralité de canaux physiques, et transmettre simultanément les données sur le canal physique combiné et sur au moins un autre canal physique parmi la pluralité de canaux, le canal physique combiné et ledit autre canal physique étant séparés au moyen d'un multiplexage de codes. L'invention concerne en outre un terminal radio correspondant et un nœud d'accès radio correspondant, et des programmes informatiques correspondants.
PCT/EP2016/051925 2015-01-30 2016-01-29 Procédé de multiplexage de canaux physiques de liaison montante pour obtenir une bonne couverture WO2016120452A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050053035A1 (en) * 2003-08-16 2005-03-10 Samsung Electronics Co., Ltd. Method and apparatus for providing uplink packet data service on uplink dedicated channels in an asynchronous wideband code division multiple access communication system
WO2006116102A2 (fr) * 2005-04-28 2006-11-02 Qualcomm Incorporated Utilisation de porteuses multiples dans des systemes de transmission de donnees
EP1724978A2 (fr) * 2005-05-20 2006-11-22 Nokia Corporation Contrôle de ressources radio dans un système HSUPA
WO2011071430A1 (fr) * 2009-12-11 2011-06-16 Telefonaktiebolaget L M Ericsson (Publ) Procédé et agencement de commande d'ordonnancement dans un système de télécommunication

Patent Citations (4)

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Publication number Priority date Publication date Assignee Title
US20050053035A1 (en) * 2003-08-16 2005-03-10 Samsung Electronics Co., Ltd. Method and apparatus for providing uplink packet data service on uplink dedicated channels in an asynchronous wideband code division multiple access communication system
WO2006116102A2 (fr) * 2005-04-28 2006-11-02 Qualcomm Incorporated Utilisation de porteuses multiples dans des systemes de transmission de donnees
EP1724978A2 (fr) * 2005-05-20 2006-11-22 Nokia Corporation Contrôle de ressources radio dans un système HSUPA
WO2011071430A1 (fr) * 2009-12-11 2011-06-16 Telefonaktiebolaget L M Ericsson (Publ) Procédé et agencement de commande d'ordonnancement dans un système de télécommunication

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ERICSSON: "Enhanced uplink (EUL) coverage improvements", vol. RAN WG1, no. Athens, Greece; 20150209 - 20150213, 31 January 2015 (2015-01-31), XP050948928, Retrieved from the Internet <URL:http://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_80/Docs/> [retrieved on 20150131] *

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