Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
  • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
  • H04B7/0413—MIMO systems
  • H04B7/0452—Multi-user MIMO systems
• • 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
  • H04L5/0023—Time-frequency-space
• • 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
  • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
  • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
  • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
  • H04B7/0686—Hybrid systems, i.e. switching and simultaneous transmission
  • H04B7/0689—Hybrid systems, i.e. switching and simultaneous transmission using different transmission schemes, at least one of them being a diversity transmission scheme
• • 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
  • H04L5/0026—Division using four or more dimensions, e.g. beam steering or quasi-co-location [QCL]

Definitions

• Embodiments herein relate generally to demodulation reference signal (DM-RS) design for LTE Advanced, i.e. release 10.
• DM-RS demodulation reference signal
• the solution is related to standardization specification, where 3GPP RAN1 is discussing the relation between layer and DM-RS port.
• the disclosed invention is discussed based on the Evolved Universal Terrestrial Radio Access (E-UTRA) system (which is also commonly referred to as the Long-Term Evolution (LTE) of the widely deployed WCDMA systems.
• E-UTRA Evolved Universal Terrestrial Radio Access
• LTE Long-Term Evolution
• the 3rd Generation Partnership Project (3GPP) is responsible for the standardization of UMTS (Universal Mobile Telecommunication Service) system and LTE (Long Term Evolution).
• LTE is a technology for realizing high-speed packet-based communication that can reach high data rates both in the downlink and in the uplink, which is thought as a next generation mobile communication system of the UMTS system.
• the 3GPP work on LTE is also referred to as E-UTRAN (Evolved Universal Terrestrial Access Network).
• the first release of LTE referred to as release-8 (Rel-8) can provide peak rates of 300 Mbps, a radio-network delay of e.g. 5 ms or less, a significant increase in spectrum efficiency and a network architecture designed to simplify network operation, reduce cost, etc.
• LTE In order to support high data rates, LTE allows for a system bandwidth of up to 20 MHz. LTE is also able to operate in different frequency bands and can operate in at least FDD (Frequency Division Duplex) and TDD (Time Division Duplex).
• FDD Frequency Division Duplex
• TDD Time Division Duplex
• the modulation technique or the transmission scheme used in LTE is known as OFDM (Orthogonal Frequency Division Multiplexing).
• LTE-advanced International Mobile Telecommunications
• LTE-advanced Long Term Evolution-advanced
• LTE-advanced Long Term Evolution-advanced
• LTE and LTE-advanced are an example of MIMO (Multiple-Input, Multiple-Output) radio systems.
• MIMO Multiple-Input, Multiple-Output
• WiMAX Worldwide Interoperability for Microwave Access
• Reference signal as also called predefined training sequence/signal, is extensively applied in wireless communication systems with the aim to improve detection performance.
• Figure 1 shows a basic communication system with reference signals, where a system consists of a transmitter and a receiver. RS is predefined between transmitter and receiver. Therefore, at the receiver, channel estimation is applied first by using RS targeting to do coherent detection for data recovery.
• LTE Rel-10 in order to fulfill LTE-advanced downlink spectral efficiency, 30bps/Hz, up to 8 layer transmission should be supported using some kind of advanced antenna configuration, e.g. 8x8 high-order MIMO. Accordingly, channel state information (CSI) measurement and channel demodulation for data recovery for up to 8 layers transmission should be defined in Rel-10.
• CSI channel state information
• CRS cell-specific reference signals
• CSI-RS Channel state information reference signals
• CRS will be used for both channel measurement and channel demodulation for downlink transmission modes 1/2/3/4/5/6 while DRS (dedicated RS or UE-specific RS) is used for channel demodulation for downlink transmission mode 7 (i.e. single layer beamforming).
• DRS dedicated RS or UE-specific RS
• DM-RS Demodulation reference signals
• o UE-specific i.e. the PDSCH and the demodulation reference signals intended for a specific UE are subject to the same precoding operation
• DM-RS design only. Some decisions were made in the previous RAN1 meetings on DM-RS design for normal CP [3].
• the rank 1-4 DM-RS pattern for normal CP is agreed to support up to 4 layers transmission, i.e. total 4 DM-RS ports are defined.
• total 12 resource elements per layer are agreed as DM-RS overhead (either in the grey '1' or '2' in Figure 2).
• Two CDM groups (grey) occupy different subcarrier in frequency domain, i.e. CDM+FDM as the basic multiplexing scheme.
• Each CDM group uses orthogonal code covers (OCC) with each length of 2 to multiplex up to two layers. In case of up to 2 layers transmission, only CDM group 1 exists, as marked in grey ⁇ '.
• rank 5-8 DM-RS pattern design is being discussed in 3GPP RAN1 to further define total 8 DM-RS ports.
• the following pattern as shown in Figure 3 is promising and preferred, where OCC length of 4 is simply used for each CDM group to make a soft extension. This pattern share same RS position and keep two CDM groups unchanged, which can ease UE implementation to a great extent.
• LTE Rel-10 in the downlink 8-by-X single user spatial multiplexing, it is decided that up to two transport blocks can be transmitted to a scheduled UE in a subframe per downlink component carrier [2].
• Each transport block is assigned its own modulation and coding scheme.
• a transport block is associated with a codeword and layer mapping shall be done according to the mapping pattern, as shown in Figure 4. From Figure 4, it should be noted that each codeword (CW) is associated with up to 4 layers and for odd rank mapping, unequal layer allocation will happen between two CWs. Due to the introduction of DM-RS for data demodulation, the same number of DM- RS ports as transmitted layers will be transmitted. This results in a new mapping between layer and DM-RS port. The change from Rel-8 to Rel-10 is obviously needed, as shown in Figure s.
• This solution proposes a common mapping pattern between transmission layers to DM-RS ports for both SU-MIMO and MU-MIMO in case of downlink multi-layer transmission in LTE Rel-10. More specifically, we use a mapping principle, as called intra- CW mapping here, to make two CWs mapped into different CDM groups for beyond rank 2 transmission (rank 1-2 mapping can be reused in Rel-9). This mapping principle can avoid inter-codeword interference when channel estimation per layer is applied, which can keep HARQ processing independent.
• the principle of intra-CW mapping is provided in Figure 6. With detailed description to be provided in the next section, the proposed mapping pattern has the following advantages:
• Figure 1 shows a wireless system with reference signals
• Figure 2 shows agreed rank 1-4 DM-RS pattern for normal CP (3 OFDM for control channel is assumed),
• Figure 4 shows agreed codeword-to-layer mapping from rank 1 to rank 8
• Figure 5 shows new module of layer-to-DM RS mapping in Rel-10
• Figure 7 shows proposed layer-to-DM RS port mapping
• Figure 8 shows one example of layer-to-DM RS port mapping for MU-MIMO case
• Figure 9 shows a schematic overview of a radio communications network
• Figure 10 shows a schematic overview of a transmitter.
• CDM group is associated with up to 4 DM-RS ports.
• DM-RS ports For illustration purpose, we define the DM-RS ports as follows • CD group 1 : DM-RS ports 1/2/5/6
• CDM group 2 DM-RS ports 3/4/7/8
• Step-1 allocate each UE according to intra-CW mapping principle
• Step-2 repeat step-1 for other co-scheduled UEs
• control signalling is needed to indicate each UE which DM-RS ports are allocated. This can guarantee UEs to perform channel estimation using proper DM-RS.
• Figure 9 shows a transmitter that maps according to the present solution and signals the mapping to the receiver.
• Figure 10 shows a transmitter comprising a mapping/processing circuitry for example a processor, performing a mapping according to a mapping pattern between transmission layers to DM-RS ports in LTE Rel-10, where DM-RS ports will be basically used for data demodulation to support multiple LTE-Advanced features.
• the transmitter transmits the mapping to the receivers over a transmission circuitry.
• mapping should be defined in specification.
• the proposed mapping pattern has the following advantages:

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

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• 2010
  • 2010-01-12 WO PCT/CN2010/000043 patent/WO2011085509A1/en not_active Ceased
  • 2010-06-24 CA CA2786810A patent/CA2786810C/en active Active
  • 2010-06-24 WO PCT/SE2010/050725 patent/WO2011087417A1/en not_active Ceased
  • 2010-06-24 US US13/520,803 patent/US20120275414A1/en not_active Abandoned
  • 2010-06-24 EP EP16194166.1A patent/EP3174220B1/en not_active Not-in-force
  • 2010-06-24 JP JP2012547981A patent/JP5726900B2/ja active Active
  • 2010-06-24 EP EP10843337.6A patent/EP2524559B1/en not_active Not-in-force
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