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
  • H04L1/0036—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
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/14—Relay systems
  • H04B7/15—Active relay systems
  • H04B7/155—Ground-based stations
  • H04B7/15507—Relay station based processing for cell extension or control of coverage area
• • 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
  • H04L1/0015—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy
  • H04L1/0017—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy where the mode-switching is based on Quality of Service requirement
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L61/00—Network arrangements, protocols or services for addressing or naming
  • H04L61/50—Address allocation
  • H04L61/5038—Address allocation for local use, e.g. in LAN or USB networks, or in a controller area network [CAN]
• • 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
  • 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
  • H04L2001/0097—Relays
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W24/00—Supervisory, monitoring or testing arrangements
  • H04W24/02—Arrangements for optimising operational condition
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W8/00—Network data management
  • H04W8/26—Network addressing or numbering for mobility support
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W84/00—Network topologies
  • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
  • H04W84/04—Large scale networks; Deep hierarchical networks
  • H04W84/042—Public Land Mobile systems, e.g. cellular systems
  • H04W84/047—Public Land Mobile systems, e.g. cellular systems using dedicated repeater stations

Definitions

• the present invention relates to a method and a corresponding relay node (RN) for executing multiple media access control protocol data unit (MAC PDU) deliveries in a backhaul link between a donor eNB (DeNB) and a RN in a wireless communication system with a RN.
• RN relay node
• MAC PDU media access control protocol data unit
• 3 GPP Long Term Evolution
• LTE Long Term Evolution
• multi-service support such as VoIP (Voice over Internet Protocol), HTTP(Hyper Text Transmission Protocol), and video services.
• VoIP Voice over Internet Protocol
• HTTP Hyper Text Transmission Protocol
• video services These services have different service requirements, which are captured by 3GPP TS 23.203 in terms of QCI (QoS Class Identifier).
• QCI QoS Class Identifier
• the service characteristics are indicated by resource type (GBR/Non-GBR) (Guarded Bit Rate/Non-Guarded Bit Rate), priority, packet delay budget (PDB) and packet error loss rate (PELR).
• resource type GRR/Non-GBR
• PDB packet delay budget
• PELR packet error loss rate
• conversational voice service requires packet delay budget up to 100ms and can tolerate higher packet error rate up to 1 %, while video services (buffered streaming) need to meet the requirements of packet data budget up to 300ms and 10 "6 packet error rate.
• packet delay budget up to 100ms and can tolerate higher packet error rate up to 1 %
• video services need to meet the requirements of packet data budget up to 300ms and 10 "6 packet error rate.
• different measures should be employed for the implementation of underlying bearer access networks, e.g. the configuration of scheduling and link layer functions.
• Type-1 relay has been adopted by LTE- A (Long Term Evolution- Advanced) Rel-10 as the effective solution for coverage extension and throughput enhancement at a relatively low CAPEX (CAPital Expenditures) and OPEX (Operation Expenditure).
• the new introduced network element i.e., RN
• the communication link between DeNB and RN is a backhaul link, while the communication link between RN and UE is an access link.
• TDM time division multiplexing
• MAC entity for the data delivery between RN's UE functionality and DeNB. All VoIP data and TCP (Transmission Control Protocol) data are encapsulated and transmitted with the same QoS settings depending on the single MAC entity configuration. These packets with different QoS requirements experience same packet loss probability and HARQ retransmission delay. For VoIP service, less retransmission and relatively higher packet loss probability are tolerable and maximum retransmission and lower packet loss can also be accepted. It would cause a lot of inefficiency in the relay system such that radio resources in the cell will be wasted if there are no further improvements on the Un interface for HARQ.
• TCP Transmission Control Protocol
• the aim of the present invention is to provide a method and a corresponding RN of executing multiple MAC PDU deliveries in a backhaul link between a donor eNB and a RN in a wireless communication system with a RN.
• a better QoS guarantee is provided for different kinds of services.
• a method of executing multiple media access control protocol data unit deliveries in a backhaul link between a donor eNB and a relay node in a wireless communication system with a relay node comprises the steps of: the donor eNB allocating multiple C-RNTIs (cell-radio network temporary identity) for the relay node for multiple service flows with different QoS requirements, in the relay node startup stage; configuring multiple media access control entities identified by the multiple C-RNTIs in the relay node; and executing the multiple media access control protocol data unit deliveries for packet data of the multiple service flows with the donor eNB in the backhaul link by using the configured multiple media access control entities.
• C-RNTIs cell-radio network temporary identity
• the step of donor eNB allocating multiple C-RNTIs for the relay node for multiple service flows with different QoS requirements includes: the donor eNB determining the amount of the allocated C-RNTIs dynamically according to channel condition, load condition and carried user amount.
• the channel condition includes at least one of measured SINR and power headroom report from the relay node.
• the step of the donor eNB allocating multiple C-RNTIs for the relay node for multiple service flows with different QoS requirements includes: either the donor eNB or the relay node launching reallocation for the C-RNTIs, when the amount of the allocated C-RNTIs does not satisfy the QoS requirement of the multiple service flows.
• the method further comprises: configuring and managing the mapping relation between the service flows and logical channel and the multiple C-RNTIs according to the QoS requirement of each of the multiple service flows.
• the step of configuring and managing the mapping relation between the service flows and logical channel and the multiple C-RNTIs includes: configuring and managing independently the mapping relation for uplink and downlink between the donor eNB and the relay node.
• the step of executing the multiple media access control protocol data unit deliveries for packet data of the multiple service flows with the donor eNB in the backhaul link by using the configured multiple media access control entities includes: the donor eNB sending multiple relay PDCCH to the relay node, the relay PDCCH indicating resource block assignment information, modulation and coding scheme and cyclic redundancy check scrambled by the corresponding C-RNTIs; the relay node implementing blind decoding for the relay PDCCH by using allocated primary C-RNTIs, the primary C-RNTIs being specified C-RNTIs known to both the donor eNB and the relay node; and the relay node implementing, blind decoding for secondary C-RNTIs appearing in a subframe, in the same offset position in the search space of the relay PDCCH possibly carrying the secondary C-RNTIs, by using offset in the search space of a PDCCH carrying the primary the C-RNTIs, when the relay PDCCH matching the primary C-RNTIs is found.
• the step that executing the multiple media access control protocol data unit deliveries for packet data of the multiple service flows with the donor eNB in the backhaul link by using the configured multiple media access control entities includes: the donor eNB sending multiple relay PDCCH to the relay node, the relay PDCCH indicating resource block assignment information, modulation and coding scheme and cyclic redundancy check scrambled by the corresponding C-RNTIs; the relay node implementing blind decoding for the relay PDCCH by using the allocated primary C-RNTIs, the primary C-RNTIs being known to both the donor eNB and the relay node; and determining the secondary C-RNTIs scheduled for the subframe based on the information embedded in the DCI of the relay PDCCH, and searching again the relay PDCCH for the determined secondary cell-radio network temporary identities and decoding, when the relay PDCCH matching the primary C-RNTIs is found.
• the step of executing the multiple media access control protocol data unit deliveries for packet data of the multiple service flows with the donor eNB in the backhaul link by using the configured multiple media access control entities includes: enabling each subframe to support multiple HARQ processes, and each HARQ process is indicated by the corresponding relay PDCCH explicitly, in the HARQ procedure on the Un interface of the backhaul link.
• the wireless communication system is a multi-hop relay system.
• a relay node for executing multiple media access control protocol data unit deliveries in a backhaul link between a donor eNB and a relay node in a wireless communication system
• the relay node comprises: a configuring means, for configuring multiple media access control entities identified by the multiple C-RNTIs in the relay node, according to multiple C-RNTIs for the relay node allocated by the donor eNB for multiple service flows with different QoS requirements, in the relay node startup stage; and a delivering means, for executing the multiple media access control protocol data unit deliveries for packet data of the multiple service flows with the donor eNB in the backhaul link by using the configured multiple media access control entities.
• FIG.l shows a schematic diagram of the architecture and frame structure of an E-UTRAN (Evolved Universal Terrestrial Radio Access Network) with a LTE- Advanced RN;
• E-UTRAN Evolved Universal Terrestrial Radio Access Network
• FIG.2 shows a flowchart of a method of executing multiple MAC PDU deliveries in a backhaul link according to the present invention
• FIG.3 shows a schematic diagram of service flows mapping on the Un interface
• FIG.4 shows a sequence diagram of RN startup procedures
• FIG.5 shows a sequence diagram of RN-initiated C-RNTI reallocation/release procedures
• FIG.6 shows a schematic diagram of the implicitly assisted blind decoding
• FIG.7 shows a schematic diagram of downlink HARQ process timing on the Un interface
• FIG.8 shows a block diagram of a RN according to the present invention.
• Un interface is a new-defined interface in LTE-Advanced system, the most straightforward method is to totally inherit the features of the Uu interface, which has been fully designed in LTE Rel-8 technical specifications. There are some drawbacks on the Un interface in LTE- A Rel-10 when using the legacy single MAC entity configuration defined on the Uu interface:
• Un interface since it aggregates the traffic loads of multiple UEs managed by a RN.
• the HARQ retransmission may block the subsequent new data transmission, thus degrade the throughput of both downlink (DL) and uplink (UL), which may lead to more transmission delay.
• One MAC entity means that only one MAC PDU is transmitted in one transmission time interval (TTI), unless spatial multiplexing or carrier aggregation is employed. That is, multiple service flows with different QoS requirements (e.g. VoIP and HTTP service) have to be encapsulated into a MAC PDU, which is associated with the same set of link configuration parameters.
• QoS requirements e.g. VoIP and HTTP service
• the unique link configuration means all these services flows are protected equally, and it may violate the original intention of QoS parameter design.
• the present invention provides a method of enabling multiple MAC PDU deliveries over a Un interface, i.e., for RN implementation, a RN utilizes multiple MAC entities to communicate with a DeNB on the Un interface.
• MAC entity is indicated by C-RNTI (Cell- Radio Network Temporary Identification)
• C-RNTI Cell- Radio Network Temporary Identification
• multiple MAC PDU deliveries mean that multiple C-RNTIs will be allocated for a RN when it works as the UE on the Un interface, i.e. the enhanced UE.
• FIG.2 shows a flowchart of a method of executing multiple MAC PDU deliveries in a backhaul link according to the present invention.
• step 201 the DeNB allocates multiple C-RNTIs for the RN for multiple service flows with different QoS requirements in the RN startup stage. Then, in step 203, multiple MAC entities identified by the multiple C-RNTIs are configured in the RN. At last, in step 205, the multiple MAC PDU deliveries are executed for packet data of the multiple service flows with the DeNB in the backhaul link by using the configured multiple MAC entities.
• the RN negotiates with the DeNB about how many C-RNTIs (MAC entities) need to be allocated.
• the MAC entity configuration can be initiated at the RN startup stage, where the RN indicates its identity to the DeNB, and the DeNB can give a default configurations based on the deployment scenarios and interference conditions.
• either the DeNB or the RN can launch the reallocation procedures of the C-RNTIs (the reconfiguration procedures of the MAC entities), more particularly, the allocation procedures of the secondary C-RNTIs.
• the secondary C-RNTIs will be described in detail later.
• RN is allocated implicitly or explicitly so as to use a set of RN C-RNTI. This will be described in detail later.
• FIG.3 shows a schematic diagram of service flows mapping on the Un interface.
• the DeNB needs to define a new functional element to configure and mange the mapping relation between the service flows and logical channel and/or C-RNTI.
• the functional element may coordinate with the packet scheduler.
• the relations may be decided by the QoS requirement of each service flow, e.g. service types (GBR/non-GBR), PDB and PELR, etc.
• one service flow may be mapped to multiple logical channels, which may belong to one or more C-RNTIs.
• mapping relations are independently configured for DL and UL respectively.
• the scheduler located at the DeNB can be same as the scenario of the single C-RNTI configuration for the RN, ( e.g. maintaining the same scheduling queue and rules as before). The only difference is that the scheduler may need to cooperate with the aforementioned functional elements to decide how many transport blocks should be generated, and to decide the modulation coding scheme, the number of the retransmission etc.
• the DeNB sends multiple R-PDCCHs (Relay Physical Downlink Control CHannel) to the RN to indicate the resource block assignment information, modulation and coding scheme and cyclic redundancy check scrambled by the corresponding RN C-RNTI.
• R-PDCCHs Reslay Physical Downlink Control CHannel
• the RN implements blind decoding of R-PDCCH to achieve the information on the scheduling of MAC PDU.
• the detailed procedures may be but not limited as follows.
• the RN executes the exhaustive search using all the possible allocated C-RNTIs.
• the implicit information may correspond to a certain subframe and the former fault transmission, and thus a subset of the allocated C-RNTIs may be searched.
• a primary C-RNTI may be firstly sought. It may correspond to a certain subframe. Then, in the R-PDCCH using the primary C-RNTI, the number of employed C-RNTI, or which C-RNTI is used in this TTI is obtained.
• the blind decoding approach mentioned above can be used for the resource allocation of both downlink and uplink.
• FIG.4 shows a sequence diagram of RN startup procedures.
• the RN In the RN initial access stage, when the RN powers up, the RN needs to first acquire the Un interface channel and the system configuration parameters. Next, the RN has to connect to the DeNB, and be recognized and authenticated by the core network to work as a RN. Finally, after the DeNB knows that the RN is authenticated, it provides the correct system configuration parameters for the RN to begin the operation. That is, the RN should indicate its identity different from a regular UE, and such an indication may occur in the step (1), (3) or (5) of FIG.4.
• the DeNB evaluates the channel conditions, e.g. the measured SINR, power headroom report from the RN, etc.
• the DeNB decides how many C-RNTIs should be initially configured dynamically according to channel condition, load condition and carried user amount.
• step (8) i.e. RRC configuration request, some information elements may need to be added to indicate the multiple MAC entities configuration, including the allocated C-RNTIs and other parameters.
• FIG.5 shows a sequence diagram of RN-initiated C-RNTI reallocation/release procedures.
• the reallocation for the C-RNTIs should be launched. This operation may be initiated by either the DeNB or the RN.
• FIG.5 only shows the RN- initiated procedure.
• the mapping between the RB and logical channel is unique.
• the mapping from the RB to logical channel and C-RNTIs is a one-to-many case.
• more logical channels and C-RNTIs are to be allocated to the RN so as to alleviate the head-of-line blocking problem.
• a R-PDCCH carries a message known as downlink control information (DCI), which includes resource assignments and other control information for a RN.
• DCI downlink control information
• several R-PDCCHs can be transmitted in a subframe.
• the CRC is scrambled with the RN C-RNTI.
• the RN will check the set of R-PDCCHs and tries to blind decode them (checking all DCI formats). Since the RN will execute several tentative decoding in its search space, up to 22 times according to the current specification, and when multiple C-RNTIs are introduced, the corresponding processing burden also increases.
• a primary C-RNTI needs to be defined in advance, which may be statically designated, or be a certain C-RNTI corresponding to the subframe number and/or the previous HARQ status.
• both the DeNB and the RN should know it uniformly.
• the RN executes the R-PDCCH blind decoding using the primary C-RNTI just like a regular UE.
• R-PDCCH matched with the primary C-RNTI When R-PDCCH matched with the primary C-RNTI is not found, it means in this subframe there is no scheduling information. Whereas the corresponding R-PDCCH is found by the RN, for example, #2 of C-RNTI 1 search space (here we assume C-RNTI 1 is as the primary C-RNTI) in the search space, as shown in 6. If other C-RNTIs, which may be called secondary C-RNTIs, appear in this subframe, they may have the same offset as the primary C-RNTI, e.g. #2 of C-RNTI 2 (secondary C-RNTI) search space.
• the RN only searches the partial R-PDCCHs with the same offset as the primary C-RNTI to decide if there are more additional scheduling information. Thus exhaustive search is not necessary and the complexity is greatly reduced.
• a primary C-RNTI may need to be defined in advance, which can be statically designated, or be a certain C-RNTI corresponding to the subframe number and/or the previous HARQ status.
• both the DeNB and the RN should know it uniformly.
• the RN executes the R-PDCCH blind decoding using the primary C-RNTI just like a regular UE.
• R-PDCCH matched with the primary C-RNTI When R-PDCCH matched with the primary C-RNTI is not found, it means in this subframe there is no DL scheduling and UL scheduling grant. Whereas the corresponding R-PDCCH is found, based on the embedded information in the DCI, e.g. the index to other C-RNTIs, the RN can know which other C-RNTIs, which may be called secondary C-RNTIs, are employed for scheduling in this subframe.
• the additional R-PDCCH can be searched and decoded according to the procedures same as the primary C-RNTI.
• FIG.7 shows a schematic diagram of uplink HARQ process timing on the Un interface.
• each subframe can support multiple DL HARQ procedures.
• R-PDCCH with uplink grant is transmitted to the RN by DeNB as the P2 HARQ process.
• the UL data is transmitted to the DeNB by the RN.
• eNB uses UL grant with non-toggled New Data Indication (NDI) bit to perform adaptive UL HARQ retransmission in subframe 2# of next frame #n+l .
• NDI non-toggled New Data Indication
• each backhaul subframe in the UL HARQ process, enable each backhaul subframe to correspond to multiple HARQ processes, which is indicated by the corresponding R-PDCCH explicitly.
• the retransmission of P2 is not interfered by the normal new data transmission of P5 in subframe #2.
• the maximum number of HARQ process supported in a subframe is dynamic or semi-dynamic, and this corresponds to the number of the allocated C-RNTIs.
• different modulation coding schemes can be applied on the respective transport blocks in a subframe.
• FIG.8 shows a block diagram of a RN according to the present invention.
• the RN includes configuring means 801 and delivering means 803.
• the configuring means 801 configures multiple MAC entities identified by the multiple C-RNTIs in the RN, according to multiple C-RNTIs for the RN allocated by the DeNB for multiple service flows with different QoS requirements in the RN startup stage.
• the delivering means 803 executes multiple MAC PDU deliveries for packet data of the multiple service flows with the DeNB in the backhaul link by using the configured multiple MAC entities.
• Multi-hop relay technique is a cost-efficient way to extend coverage and enhance user throughput (especially for cell-edge users), and it is also the key candidate technique in LTE-Advanced.
• the proposed solution can improve the performance of Packet Error Loss Rate for better QoS guarantee, with very small modifications to the current specification.
• the solution has a good scalability, and it can be easily extended to the more than two-hop relay scenarios.
• the present invention can achieve the trade-off between retransmission operation and delay as well as PELR for differentiated services through overcoming the shortage of inconsistent link configuration on the Un interface.
• the present invention can optimize QoS control and R-PDCCH decoding complexity within the scope of RAN and without the impacts on core network.
• the present invention can easily fall back to the single MAC PDU delivery across the Un interface, which ensures its robustness.
• the reduced size of transport block decreases the transport block error probability and increases the total system throughput.
• the reduced size of transport block decreases the transport block error probability, and thus decreases the average transmission delay of the packet data.
• the method of the present invention further provides the additional flexibility for meeting QoS requirements in relay-enabled access network.
• the method of the present invention keeps the compatibility with the current standard specification and recent progress.
• the present invention provides a new solution to guarantee QoS in the relay system, and satisfy the backward-compatibility, i.e. no impacts on Rel-8/9/10 UEs.

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