Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
  • H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
  • H04B7/2612—Arrangements for wireless medium access control, e.g. by allocating physical layer transmission capacity
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W48/00—Access restriction; Network selection; Access point selection
  • H04W48/08—Access restriction or access information delivery, e.g. discovery data delivery
  • H04W48/10—Access restriction or access information delivery, e.g. discovery data delivery using broadcasted information
• • 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
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
  • H04W16/24—Cell structures
  • H04W16/26—Cell enhancers or enhancement, e.g. for tunnels, building shadow
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04J—MULTIPLEX COMMUNICATION
  • H04J11/00—Orthogonal multiplex systems, e.g. using WALSH codes
  • H04J11/0069—Cell search, i.e. determining cell identity [cell-ID]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/26—Systems using multi-frequency codes
  • H04L27/2601—Multicarrier modulation systems
  • H04L27/2602—Signal structure
  • H04L27/261—Details of reference signals
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/26—Systems using multi-frequency codes
  • H04L27/2601—Multicarrier modulation systems
  • H04L27/2647—Arrangements specific to the receiver only
  • H04L27/2655—Synchronisation arrangements
  • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
  • H04L27/2692—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with preamble design, i.e. with negotiation of the synchronisation sequence with transmitter or sequence linked to the algorithm used at the receiver
• • 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
  • H04L5/0032—Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
  • H04L5/0035—Resource allocation in a cooperative multipoint environment
• • 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
  • H04L5/0053—Allocation of signalling, i.e. of overhead other than pilot signals
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W74/00—Wireless channel access
  • H04W74/002—Transmission of channel access control information
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L25/00—Baseband systems
  • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
  • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
  • H04L25/03828—Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W56/00—Synchronisation arrangements
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
  • H04W88/08—Access point devices
  • H04W88/085—Access point devices with remote components

Definitions

• Certain embodiments of the present disclosure generally relate to wireless communication and, more particularly, to techniques for activating opportunistic relays.
• Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE) systems, and orthogonal frequency division multiple access (OFDMA) systems.
• CDMA code division multiple access
• TDMA time division multiple access
• FDMA frequency division multiple access
• LTE 3GPP Long Term Evolution
• OFDMA orthogonal frequency division multiple access
• a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals.
• Each terminal communicates with one or more base stations via transmissions on the forward and reverse links.
• the forward link (or downlink) refers to the communication link from the base stations to the terminals
• the reverse link (or uplink) refers to the communication link from the terminals to the base stations.
• This communication link may be established via a single-in-single-out, multiple-in-signal-out or a multiple-in- multiple-out (MIMO) system.
• MIMO multiple-in- multiple-out
• Some systems may utilize a relay base station that relays messages between a donor base station and wireless terminals.
• the relay base station may communicate with the donor base station via a backhaul link and with the terminals via an access link.
• the relay base station may receive downlink messages from the donor base station over the backhaul link and relay these messages to the terminals over the access link.
• the relay base station may receive uplink messages from the terminals over the access link and relay these messages to the donor base station over the backhaul link.
• Certain aspects of the present disclosure provide a method for wireless communications by a node belonging to a cluster of cells having a macro node and one or more other type nodes.
• the method generally includes transmitting a tertiary synchronization signal (TSS) that uniquely identifies the node within the cluster, wherein the cluster is identified by a primary synchronization signal (PSS) and secondary synchronization signal (SSS).
• TSS tertiary synchronization signal
• PSS primary synchronization signal
• SSS secondary synchronization signal
• Certain aspects of the present disclosure provide a method for wireless communications by a user equipment (UE) within a cluster of cells having a macro node and one or more other type nodes.
• the method generally includes detecting a tertiary synchronization signal (TSS), wherein the cluster is identified by a primary synchronization signal (PSS) and secondary synchronization signal (SSS) and identifying a node within the cluster that transmitted the TSS.
• TSS primary synchronization signal
• SSS secondary synchronization signal
• Certain aspects of the present disclosure provide a method for wireless communications by a node belonging to a cluster of cells having a macro node and one or more other type nodes.
• the method generally includes participating in at least a portion of a random access channel (RACH) procedure with a user equipment (UE) and determining, based on capability information obtained during the portion of the RACH procedure, capability of the UE to detect and communicate with other type nodes in the cluster.
• RACH random access channel
• UE user equipment
• Certain aspects of the present disclosure provide a method for wireless communications by a user equipment (UE) within a cluster of cells having a macro node and one or more other type nodes.
• the method generally includes participating in at least a portion of a random access channel (RACH) procedure with one of the other type nodes in the cluster and conveying, during the portion of the RACH procedure, capability of the UE to detect and communicate with other type nodes in the cluster.
• RACH random access channel
• Certain aspects of the present disclosure provide an apparatus for wireless communications by a node belonging to a cluster of cells having a macro node and one or more other type nodes.
• the apparatus generally includes means for transmitting a tertiary synchronization signal (TSS) that uniquely identifies the node within the cluster, wherein the cluster is identified by a primary synchronization signal (PSS) and secondary synchronization signal (SSS).
• TSS tertiary synchronization signal
• PSS primary synchronization signal
• SSS secondary synchronization signal
• Certain aspects of the present disclosure provide an apparatus for wireless communications by a user equipment (UE) within a cluster of cells having a macro node and one or more other type nodes.
• the apparatus generally includes means for detecting a tertiary synchronization signal (TSS), wherein the cluster is identified by a primary synchronization signal (PSS) and secondary synchronization signal (SSS) and means for identifying a node within the cluster that transmitted the TSS.
• TSS tertiary synchronization signal
• PSS primary synchronization signal
• SSS secondary synchronization signal
• Certain aspects of the present disclosure provide an apparatus for wireless communications by a node belonging to a cluster of cells having a macro node and one or more other type nodes.
• the apparatus generally includes means for participating in at least a portion of a random access channel (RACH) procedure with a user equipment (UE) and means for determining, based on capability information obtained during the portion of the RACH procedure, capability of the UE to detect and communicate with other type nodes in the cluster.
• RACH random access channel
• UE user equipment
• Certain aspects of the present disclosure provide an apparatus for wireless communications by a user equipment (UE) within a cluster of cells having a macro node and one or more other type nodes.
• the apparatus generally includes means for participating in at least a portion of a random access channel (RACH) procedure with one of the other type nodes in the cluster and means for conveying, during the portion of the RACH procedure, capability of the UE to detect and communicate with other type nodes in the cluster.
• RACH random access channel
• Certain aspects of the present disclosure provide an apparatus for wireless communications by a node belonging to a cluster of cells having a macro node and one or more other type nodes.
• the apparatus generally includes at least one processor configured to transmit a tertiary synchronization signal (TSS) that uniquely identifies the node within the cluster, wherein the cluster is identified by a primary synchronization signal (PSS) and secondary synchronization signal (SSS) and a memory coupled with the at least one processor.
• TSS tertiary synchronization signal
• PSS primary synchronization signal
• SSS secondary synchronization signal
• Certain aspects of the present disclosure provide an apparatus for wireless communications by a user equipment (UE) within a cluster of cells having a macro node and one or more other type nodes.
• the apparatus generally includes at least one processor configured to detect a tertiary synchronization signal (TSS), wherein the cluster is identified by a primary synchronization signal (PSS) and secondary synchronization signal (SSS) and identify a node within the cluster that transmitted the TSS and a memory coupled with the at least one processor.
• TSS tertiary synchronization signal
• PSS primary synchronization signal
• SSS secondary synchronization signal
• Certain aspects of the present disclosure provide an apparatus for wireless communications by a node belonging to a cluster of cells having a macro node and one or more other type nodes.
• the apparatus generally includes at least one processor configured to participate in at least a portion of a random access channel (RACH) procedure with a user equipment (UE) and determine, based on capability information obtained during the portion of the RACH procedure, capability of the UE to detect and communicate with other type nodes in the cluster and a memory coupled with the at least one processor.
• RACH random access channel
• UE user equipment
• Certain aspects of the present disclosure provide an apparatus for wireless communications by a user equipment (UE) within a cluster of cells having a macro node and one or more other type nodes.
• the apparatus generally includes at least one processor configured to participate in at least a portion of a random access channel (RACH) procedure with one of the other type nodes in the clusterand convey, during the portion of the RACH procedure, capability of the UE to detect and communicate with other type nodes in the cluster and a memory coupled with the at least one processor.
• RACH random access channel
• Certain aspects of the present disclosure provide a program product for wireless communications by a node belonging to a cluster of cells having a macro node and one or more other type nodes, comprising a computer readable medium having instructions stored thereon.
• the instructions are generally for transmitting a tertiary synchronization signal (TSS) that uniquely identifies the node within the cluster, wherein the cluster is identified by a primary synchronization signal (PSS) and secondary synchronization signal (SSS).
• TSS tertiary synchronization signal
• PSS primary synchronization signal
• SSS secondary synchronization signal
• Certain aspects of the present disclosure provide a program product for wireless communications by a user equipment (UE) within a cluster of cells having a macro node and one or more other type nodes, comprising a computer readable medium having instructions stored thereon.
• the instructions are generally for detecting a tertiary synchronization signal (TSS), wherein the cluster is identified by a primary synchronization signal (PSS) and secondary synchronization signal (SSS) and identifying a node within the cluster that transmitted the TSS.
• TSS tertiary synchronization signal
• PSS primary synchronization signal
• SSS secondary synchronization signal
• Certain aspects of the present disclosure provide a program product for wireless communications by a node belonging to a cluster of cells having a macro node and one or more other type nodes, comprising a computer readable medium having instructions stored thereon.
• the instructions are generally for participating in at least a portion of a random access channel (RACH) procedure with a user equipment (UE) and determining, based on capability information obtained during the portion of the RACH procedure, capability of the UE to detect and communicate with other type nodes in the cluster.
• RACH random access channel
• UE user equipment
• Certain aspects of the present disclosure provide a program product for wireless communications by a user equipment (UE) within a cluster of cells having a macro node and one or more other type nodes, comprising a computer readable medium having instructions stored thereon.
• the instructions are generally for participating in at least a portion of a random access channel (RACH) procedure with one of the other type nodes in the cluster and conveying, during the portion of the RACH procedure, capability of the UE to detect and communicate with other type nodes in the cluster.
• RACH random access channel
• FIG. 1 illustrates a multiple access wireless communication system, according to aspects of the present disclosure.
• FIG. 2 is a block diagram of a communication system, according to aspects of the present disclosure.
• FIG. 3 illustrates an example frame structure, according to aspects of the present disclosure.
• FIG. 4 illustrates an example sub frame resource element mapping, according aspects of the present disclosure.
• FIG. 5 illustrates an example wireless communication system, according aspects of the present disclosure.
• FIG. 6 illustrates an example densely deployed network, in which aspects of the present disclosure may be practiced.
• FIG. 7 illustrates an example subframe structure with tertiary synchronization signals (TSSs), according aspects of the present disclosure.
• FIG. 8 illustrates example operations that may be performed by a wireless node, according to aspects of the present disclosure.
• FIG. 9 illustrates example operations that may be performed by a user equipment (UE), according to aspects of the present disclosure.
• UE user equipment
• FIG. 10 illustrates example operations of a random access channel (RACH) procedure that may be performed by a wireless node, according to aspects of the present disclosure.
• RACH random access channel
• FIG. 11 illustrates example operations of a RACH procedure that may be performed by a user equipment (UE), according to aspects of the present disclosure.
• UE user equipment
• CDMA Code Division Multiple Access
• TDMA Time Division Multiple Access
• FDMA Frequency Division Multiple Access
• OFDMA Orthogonal FDMA
• SC-FDMA Single-Carrier FDMA
• a CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc.
• UTRA includes Wideband-CDMA (W-CDMA) and Low Chip Rate (LCR).
• cdma2000 covers IS-2000, IS-95 and IS-856 standards.
• a TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM).
• GSM Global System for Mobile Communications
• An OFDMA network may implement a radio technology such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, Flash-OFDM®, etc.
• E-UTRA, E-UTRA, and GSM are part of Universal Mobile Telecommunication System (UMTS).
• UMTS Universal Mobile Telecommunication System
• LTE Long Term Evolution
• UTRA, E-UTRA, GSM, UMTS and LTE are described in documents from an organization named "3rd Generation Partnership Project" (3GPP).
• cdma2000 is described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2).
• SC-FDMA Single carrier frequency division multiple access
• SC-FDMA has similar performance and essentially the same overall complexity as those of OFDMA system.
• SC-FDMA signal has lower peak-to-average power ratio (PAPR) because of its inherent single carrier structure.
• PAPR peak-to-average power ratio
• SC-FDMA has drawn great attention, especially in the uplink communications where lower PAPR greatly benefits the mobile terminal in terms of transmit power efficiency. It is currently a working assumption for uplink multiple access scheme in 3GPP Long Term Evolution (LTE), or Evolved UTRA.
• LTE Long Term Evolution
• An access point 100 includes multiple antenna groups, one including 104 and 106, another including 108 and 110, and an additional including 112 and 114. In Fig. 1, only two antennas are shown for each antenna group, however, more or fewer antennas may be utilized for each antenna group.
• Access terminal 116 is in communication with antennas 112 and 114, where antennas 112 and 114 transmit information to access terminal 116 over forward link 120 and receive information from access terminal 116 over reverse link 118.
• Access terminal 122 is in communication with antennas 106 and 108, where antennas 106 and 108 transmit information to access terminal 122 over forward link 126 and receive information from access terminal 122 over reverse link 124.
• communication links 118, 120, 124 and 126 may use different frequency for communication.
• forward link 120 may use a different frequency then that used by reverse link 118.
• Each group of antennas and/or the area in which they are designed to communicate is often referred to as a sector of the access point.
• antenna groups each are designed to communicate to access terminals in a sector, of the areas covered by access point 100.
• the transmitting antennas of access point 100 utilize beamforming in order to improve the signal-to-noise ratio of forward links for the different access terminals 116 and 124. Also, an access point using beamforming to transmit to access terminals scattered randomly through its coverage causes less interference to access terminals in neighboring cells than an access point transmitting through a single antenna to all its access terminals.
• An access point may be a fixed station used for communicating with the terminals and may also be referred to as an access point, a Node B, or some other terminology.
• An access terminal may also be called an access terminal, user equipment (UE), a wireless communication device, terminal, access terminal or some other terminology.
• UE user equipment
• FIG. 2 is a block diagram of an embodiment of a transmitter system 210 (also known as an access point) and a receiver system 250 (also known as an access terminal) in a MIMO system 200.
• a transmitter system 210 also known as an access point
• a receiver system 250 also known as an access terminal
• traffic data for a number of data streams is provided from a data source 212 to a transmit (TX) data processor 214.
• TX transmit
• each data stream is transmitted over a respective transmit antenna.
• TX data processor 214 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data.
• the coded data for each data stream may be multiplexed with pilot data using OFDM techniques.
• the pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response.
• the multiplexed pilot and coded data for each data stream is then modulated (i.e., symbol mapped) based on a particular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols.
• the data rate, coding, and modulation for each data stream may be determined by instructions performed by processor 230.
• TX MIMO processor 220 which may further process the modulation symbols (e.g., for OFDM).
• TX MIMO processor 220 then provides Nr modulation symbol streams to N T - transmitters (TMTR) 222a through 222t.
• TMTR T - transmitters
• TX MIMO processor 220 applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.
• Each transmitter 222 receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. Nr modulated signals from transmitters 222a through 222t are then transmitted from ⁇ antennas 224a through 224t, respectively.
• the transmitted modulated signals are received by N R antennas 252a through 252r, and the received signal from each antenna 252 is provided to a respective receiver (RCVR) 254a through 254r.
• Each receiver 254 conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding "received" symbol stream.
• An RX data processor 260 then receives and processes the N R received symbol streams from N R receivers 254 based on a particular receiver processing technique to provide Nr "detected" symbol streams.
• the RX data processor 260 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream.
• the processing by RX data processor 260 is complementary to that performed by TX MIMO processor 220 and TX data processor 214 at transmitter system 210.
• a processor 270 periodically determines which pre-coding matrix to use. Processor 270 formulates a reverse link message comprising a matrix index portion and a rank value portion.
• the reverse link message may comprise various types of information regarding the communication link and/or the received data stream.
• the reverse link message is then processed by a TX data processor 238, which also receives traffic data for a number of data streams from a data source 236, modulated by a modulator 280, conditioned by transmitters 254a through 254r, and transmitted back to transmitter system 210.
• the modulated signals from receiver system 250 are received by antennas 224, conditioned by receivers 222, demodulated by a demodulator 240, and processed by a RX data processor 242 to extract the reserve link message transmitted by the receiver system 250.
• Processor 230 determines which pre-coding matrix to use for determining the beamforming weights and then processes the extracted message.
• Logical Control Channels comprise Broadcast Control Channel (BCCH), which is a DL channel for broadcasting system control information.
• PCCH Paging Control Channel
• MCCH Multicast Control Channel
• MBMS Multimedia Broadcast and Multicast Service
• Dedicated Control Channel is a point-to-point bi-directional channel that transmits dedicated control information used by UEs having an RRC connection.
• Logical Traffic Channels comprise a Dedicated Traffic Channel (DTCH), which is a point-to-point bi-directional channel, dedicated to one UE, for the transfer of user information.
• DTCH Dedicated Traffic Channel
• MTCH Multicast Traffic Channel
• Transport Channels are classified into DL and UL.
• DL Transport Channels comprise a Broadcast Channel (BCH), Downlink Shared Data Channel (DL-SDCH), and a Paging Channel (PCH), the PCH for support of UE power saving (DRX cycle is indicated by the network to the UE), broadcasted over entire cell and mapped to PHY resources which can be used for other control/traffic channels.
• the UL Transport Channels comprise a Random Access Channel (RACH), a Request Channel (REQCH), an Uplink Shared Data Channel (UL-SDCH), and a plurality of PHY channels.
• the PHY channels comprise a set of DL channels and UL channels.
• the DL PHY channels comprise: Common Pilot Channel (CPICH)
• Synchronization Channel (SCH)
• CCCH Common Control Channel
• SDCCH Shared DL Control Channel
• MCCH Multicast Control Channel
• DL-PSDCH DL Physical Shared Data Channel
• PICH Paging Indicator Channel
• the UL PHY Channels comprise:
• PRACH Physical Random Access Channel
• CQICH Channel Quality Indicator Channel
• ASICH Antenna Subset Indicator Channel
• UL-PSDCH UL Physical Shared Data Channel
• BPICH Broadband Pilot Channel
• a channel structure that preserves low PAR (at any given time, the channel is contiguous or uniformly spaced in frequency) properties of a single carrier waveform.
• Rel-8 refers to Release 8 of the LTE standard.
• FIG. 3 shows an exemplary frame structure 300 for FDD in LTE.
• the transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames.
• Each radio frame may have a predetermined duration (e.g., 10 milliseconds (ms)) and may be partitioned into 10 subframes with indices of 0 through 9.
• Each subframe may include two slots.
• Each radio frame may thus include 20 slots with indices of 0 through 19.
• Each slot may include L symbol periods, e.g., seven symbol periods for a normal cyclic prefix (as shown in FIG. 2) or six symbol periods for an extended cyclic prefix.
• the 2L symbol periods in each subframe may be assigned indices of 0 through 2L-1.
• an eNB may transmit a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) on the downlink in the center 1.08 MHz of the system bandwidth for each cell supported by the eNB.
• PSS primary synchronization signal
• SSS secondary synchronization signal
• the PSS and SSS may be transmitted in symbol periods 6 and 5, respectively, in subframes 0 and 5 of each radio frame with the normal cyclic prefix, as shown in FIG. 3.
• the PSS and SSS may be used by UEs for cell search and acquisition.
• the eNB may transmit a cell-specific reference signal (CRS) across the system bandwidth for each cell supported by the eNB.
• CRS cell-specific reference signal
• the CRS may be transmitted in certain symbol periods of each subframe and may be used by the UEs to perform channel estimation, channel quality measurement, and/or other functions.
• the eNB may also transmit a Physical Broadcast Channel (PBCH) in symbol periods 0 to 3 in slot 1 of certain radio frames.
• PBCH Physical Broadcast Channel
• the PBCH may carry some system information.
• the eNB may transmit other system information such as System Information Blocks (SIBs) on a Physical Downlink Shared Channel (PDSCH) in certain subframes.
• SIBs System Information Blocks
• PDSCH Physical Downlink Shared Channel
• the eNB may transmit control information/data on a Physical Downlink Control Channel (PDCCH) in the first B symbol periods of a subframe, where B may be configurable for each subframe.
• the eNB may transmit traffic data and/or other data on the PDSCH in the remaining symbol periods of each subframe.
• FIG. 4 shows two exemplary subframe formats 410 and 420 for the downlink with the normal cyclic prefix.
• the available time frequency resources for the downlink may be partitioned into resource blocks.
• Each resource block may cover 12 subcarriers in one slot and may include a number of resource elements.
• Each resource element may cover one subcarrier in one symbol period and may be used to send one modulation symbol, which may be a real or complex value.
• Subframe format 410 may be used for an eNB equipped with two antennas.
• a CRS may be transmitted from antennas 0 and 1 in symbol periods 0, 4, 7 and 11.
• a reference signal is a signal that is known a priori by a transmitter and a receiver and may also be referred to as pilot.
• a CRS is a reference signal that is specific for a cell, e.g., generated based on a cell identity (ID).
• ID cell identity
• Subframe format 420 may be used for an eNB equipped with four antennas.
• a CRS may be transmitted from antennas 0 and 1 in symbol periods 0, 4, 7 and 11 and from antennas 2 and 3 in symbol periods 1 and 8.
• a CRS may be transmitted on evenly spaced subcarriers, which may be determined based on cell ID. Different eNBs may transmit their CRSs on the same or different subcarriers, depending on their cell IDs.
• resource elements not used for the CRS may be used to transmit data (e.g., traffic data, control data, and/or other data).
• E-UTRA Evolved Universal Terrestrial Radio Access
• An interlace structure may be used for each of the downlink and uplink for FDD in LTE.
• Q interlaces with indices of 0 through Q - l may be defined, where Q may be equal to 4, 6, 8, 10, or some other value.
• Each interlace may include subframes that are spaced apart by Q frames.
• interlace q may include subframes q, q + Q , q + 2Q , etc., where q e ⁇ 0, Q - 1 ⁇ .
• the wireless network may support hybrid automatic retransmission (HARQ) for data transmission on the downlink and uplink.
• HARQ hybrid automatic retransmission
• a transmitter e.g., an eNB
• a receiver e.g., a UE
• all transmissions of the packet may be sent in subframes of a single interlace.
• each transmission of the packet may be sent in any subframe.
• a UE may be located within the coverage area of multiple eNBs.
• One of these eNBs may be selected to serve the UE.
• the serving eNB may be selected based on various criteria such as received signal strength, received signal quality, pathloss, etc.
• Received signal quality may be quantified by a signal-to-noise-and-interference ratio (SINR), or a reference signal received quality (RSRQ), or some other metric.
• SINR signal-to-noise-and-interference ratio
• RSRQ reference signal received quality
• the UE may operate in a dominant interference scenario in which the UE may observe high interference from one or more interfering eNBs.
• FIG. 5 illustrates an example wireless system 500 in which certain aspects of the present disclosure may be practiced.
• the wireless system 500 includes a donor base station (BS) 502 that communicates with a user equipment (UE) 504 via a relay node (RN) 506.
• the RN 506 may communicate with the donor BS 502 via a backhaul link 508 and the relay node 506 may communicate with the UE 504 via an access link 510.
• the RN 506 may receive downlink messages from the donor BS 502 over the backhaul link 508 and relay these messages to the UE 504 over the access link 510.
• RN 506 may, thus, be used to supplement a coverage area and help fill "coverage holes.”
• a RN 506 may appear to a UE 504 as a conventional BS.
• certain types of UEs may recognize a RN as such, which may enable certain features.
• a relay BS in FIG. 5
• UE user equipment
• UeNB UE relay
• nodes may include, for example remote radio heads (RRHs) or relay nodes, which may include UEs acting as relay nodes (which may be referred to as UEnBs).
• RRHs remote radio heads
• UEnBs UEs acting as relay nodes
• UEs acting as relays may be able to go into a dormant state to conserve power and become active ("light up") only at times (e.g., periodically or upon detecting an event- such as an uplink signal from a UE).
• the present disclosure provides various techniques that may be beneficial in such deployments.
• One desirable feature of such a deployment is for a UE to be able to identify, within a given cell, a particular node. Therefore, even dormant nodes may need to transmit low duty cycle signals in downlink for a UE to detect.
• the UE may then send measurement reports, for example, allowing a macro eNB to select an ideal node to serve the UE based on the reported measurements.
• a node may transmit tertiary synchronization signals (TSS) that uniquely identifies the node within a cluster, wherein the cluster itself is identified by a primary synchronization signal (PSS) and secondary synchronization signal (SSS).
• TSS tertiary synchronization signals
• PSS primary synchronization signal
• SSS secondary synchronization signal
• UEs may transmit uplink signals allowing this detection (e.g., low duty cycle signals). Reception/detection of these signals may be transmitted to a macro to help make decisions on which node should serve the UE. Further, nodes may be triggered, based on the detection to begin transmitting their own reference signals (e.g., TSS, CRS, CSI-RS, etc.).
• TSS Time Division Multiple Access
• CRS CRS
• CSI-RS CSI-RS
• aspects of the present disclosure provide techniques that may allow for a separation for radio resource management (RRM) and radio link management (RLM) from other functionalities.
• RRM radio resource management
• RLM radio link management
• PSS/SSS/CRS may provide cluster information for RRM, while a different reference signal (referred to herein as a tertiary synchronization signal or TSS) and/or CSI-RS may provide more detailed information for densely deployed nodes (e.g., RRH/UE relay).
• TSS tertiary synchronization signal
• CSI-RS may provide more detailed information for densely deployed nodes (e.g., RRH/UE relay).
• CSI-RS may provide more detailed information for densely deployed nodes (e.g., RRH/UE relay).
• FIG. 6 illustrates an example system with two clusters (labeled Cluster 1 and Cluster 2), in which TSS may be utilized.
• a macro cell eNB may transmit a PSSl/SSSl/CRSl unique to the cluster, while other type nodes transmit TSS unique to the transmitting node (e.g. TSSl, TSS2, with two nodes involved in CoMP transmitting the same TSS2). As shown, some nodes may transmit PSS/SSS/CRS/TSS, while other nodes may transmit only TSS.
• TSS TSS
• PSS/SSS e.g., with a scrambling code based on PSS/SSS
• a UE may still be able to derive the cluster ID from TSS alone.
• the macro eNB may transmit PSS2/SSS2/CSR2, with different type nodes each transmitting a unique TSS (TSS1, TSS2, and TSS3).
• the relatively dense deployment of nodes within a cluster may impose further requirements on cell IDs (e.g., on the order of 4000).
• cell IDs e.g., on the order of 4000.
• CGI close group indicator
• TSS may allow for additional cell identification.
• a TSS may be transmitted with relatively low density to save energy.
• TSS may be transmitted with a PSS/SSS like sequence structure to be implementation efficient.
• TSS time and frequency resources of TSS.
• TSS may be localized to center 6 RBs.
• TSS may be optimized for synchronized network but still be functional for asynchronous networks. It may also be desirable to limit density of transmissions in an effort to keep pilot pollution low and avoid interfering cells. Low density of the TSS can allow reuse and effectively reduce interference. It may also be desirable to provide efficient DRX support.
• TSS may provide TSS designs that allow sufficient time domain reuse.
• time reuse of TSS may allow relatively easy identification of 8-10 cells (by a UE) without interference cancelation (IC).
• PSS/SSS/TSS may work for both synchronous and asynchronous systems.
• TSS may be transmitted the same 0/5 subframe locations with PSS/SSS and can be low density (e.g., such as 40 ms periodicity or even larger).
• Certain coordinated multipoint (CoMP) scenarios may depend on CRS and CRS interference cancellation for RLM, RRM, and tracking loops.
• CSI- RS is typically used only for CSI and possible interference.
• NCT network control and timing
• PSS/SSS sequence may not be changed, but time/frequency locations may or may not be changed.
• Current UE Relay Considerations may include Network centric solutions or UE centric solutions.
• an eNB may identify which UE (or UEs) may benefit from relay operations and the eNB may send a PDCCH order for RACH with specific sequence.
• the relay UE may detect RACH and turn on upon reception of strong RACH or report RACH detection/measurement to a macro cell to coordinate what relays should turn on.
• a UE may transmit specific UL signal such as SRS.
• UE relays that detect SRS can either light up upon reception of strong SRS or report to Macro cell to coordinate who to turn on.
• a clustered deployment may be used for RRM, in which each Macro cell along with RRH or relays forms a cluster.
• RRM among clusters may be handled based on PSS/SSS/CRS.
• Cell identification as well as association to RRH or UE relay is based on a two layered approach.
• a cluster may be associated with PSS/SSS, while individual nodes transmit a TSS that uniquely identifies that node.
• a Macro cell may transmit PSS/SSS/CRS with periodicity of 5 ms. This allows a UE to identify cluster as well as perform RRM among clusters (and may be compliant to the Rel 11 NCT decision).
• Each RRH or relay node may further transmit unique signal for its identification, generally referred to herein as a TSS (Tertiary Synchronization Signal).
• TSS may be linked to each cluster (e.g., as a function of PSS/SSS). Combining PSS/SSS/TSS, a UE can uniquely identify the individual cells in a hyper dense cluster. In some cases, the use of PSS/SSS/TSS may be backwards compatible. While UEs of a first capability (so called "legacy UEs" compliant with an earlier version of a standard) may stop at PSS/SSS, UEs of a second capability (“non-legacy UEs”) may use TSS. TSS may be used for NCT or legacy carrier as well for CoMP operations. [0086] In some cases, a new RACH format may help with Autonomous Cell Association.
• Support of a new RACH format may be broadcasted in one of the SIB or MIB from each cluster, e.g. Macro cell.
• the configuration of RACH format may be further linked to the unique ID of the RRH or relay node.
• a UE may use a new RACH format with the specific configuration for Msg 1. Upon detection of Msg 1 with the specific configuration, the RRH or UE relay knows immediately which cell the UE is trying to RACH into and can respond with Msg 2 and so on without network intervention. This is autonomous mode of RRH/relay node identification and UE association.
• CSI-RS use for cell association may be limited because CSI- RS is originally introduced for CSI measurements. It was not designed to handle many other new functions such as RLM, path loss for OL PC, and others. Therefore, an enhanced signal may help separate the functionality of RLM and OLPC from CSI. In this case, CSI-RS may be used only for CSI and interference measurements.
• a Clustered RRM Approach may utilize Cell Association Based on TSS.
• TSS may be transmitted to allow further cell association for new UEs.
• PSS/SSS/CRS Upon detection of PSS/SSS/CRS, UE finds the right cluster for RRM as well as tracking loop.
• a new UE For data connections, a new UE may further detect the TSS and RACH configuration.
• a UE Upon detecting strong TSS, a UE may directly RACH into the closest TSS. This approach may provide relatively exact UL power control to the intended cell and may also reduce the congestion for the Macro cell to handle all the UEs.
• UE relays that are in dormant/energy saving mode may not need to transmit TSS, only UE relays that intend to serve users can transmit low duty cycle TSS.
• UE relays in active transmission mode further transmit CSI-RS for CSI and DM-RS based data transmissions.
• relays may need to signal loading information by TSS, e.g. by indicating whether additional users are allowed.
• the TSS design provided herein may provide various functionality, such as Cell identification, RSRP measurement for cell search, and/or PL measurement for OL PC.
• TSS time/frequency location may be localized in frequency (e.g. center 6 RB).
• TSS may also be transmitted in subframes 0/5 in order to allow efficient cell search and power saving.
• TSS density for RSRP/PL measurement, it can be transmitted at lower duty cycle than PSS/SSS, e.g. every 40 ms. It may also be an event triggered transmission, i.e. relay node will only transmit TSS when it is required to transmit (e.g., upon detecting a UE based on SRS transmissions). Frequency domain density may be similar to that of PSS/SSS (e.g. on the order of 72 tones).
• TSS time reuse may be designed to avoid/reduce pilot pollution and additional cell identification.
• Excluding PSS/SSS/PBCH there are 20 symbols. So in each radio frame, there are 20 choices for the location of TSS.
• This symbol location may provide relatively large reuse factor for interference reduction for the detection of TSS.
• the symbol location can be further tied to the PSS/SSS to convey unique ID for the relay node, e.g. the 8x required cell ID identification.
• FIG. 7 illustrates an example frame structure according to one example TSS allocation.
• TSS may be transmitted on one of the symbols in subframe 0 or 5 that is not used by PSS/SSS/PBCH. This may give the same density as PSS/SSS.
• CRS may only be used for tracking loop, so antenna ports 2 and 3 are never used.
• TSS can be transmitted on the tones defined on antenna ports 2 and 3. This may maximally reuse the structure of current Rel 8. This may give 48 tones, less than PSS/SSS density, but sufficient to convey large number of cell IDs together with PSS/SSS. It may typically be desirable to avoid collision on any CRS symbols to avoid interference.
• FIG. 8 illustrates example operations 800 that may be performed by a wireless node utilizing TSS, such as that shown in FIG. 7.
• the wireless node may be a node belonging to a cluster of cells having a macro node and one or more other type nodes.
• the operations 800 may begin, at 802, by determining a tertiary synchronization signal (TSS) that uniquely identifies the node within the cluster, wherein the cluster is identified by a primary synchronization signal (PSS) and secondary synchronization signal (SSS).
• TSS tertiary synchronization signal
• PSS primary synchronization signal
• SSS secondary synchronization signal
• the node may transmit the TSS.
• FIG. 9 illustrates example operations 900 that may be performed by a wireless node to detect TSS.
• the operations 900 may be considered complementary to those shown in FIG. 8 and may be performed, for example, by a user equipment (UE) within a cluster of cells having a macro node and one or more other type nodes.
• UE user equipment
• the operations 900 begin, at 902, by detecting a tertiary synchronization signal (TSS), wherein the cluster is identified by a primary synchronization signal (PSS) and secondary synchronization signal (SSS).
• TSS tertiary synchronization signal
• PSS primary synchronization signal
• SSS secondary synchronization signal
• the UE identifies a node within the cluster that transmitted the TSS.
• TSS can use Chu sequence or binary sequence similar to PSS/SSS. In some cases, different shifts or binary sequences can be used to provide further identification. SSS with different scrambling code may also be used to provide further identification (and the scrambling code may be a function of PSS/SSS or cell ID or global cell ID).
• TSS may be transmitted in some or all cells including Macro, RRH and UE relay, but at different rates. For example, for RRH, periodic transmission may make sense (as power may not be as big an issue as with UE relays).
• the time domain periodicity can be configurable depending on the need, e.g. to satisfy the RLM requirement. For UE relay, it should be transmitted only on an as-needed basis. If UE relay is serving any UE, it should transmit TSS periodically to maintain RLM. For UE relays that do not have any UE served, it may have other options, for example, to transmit TSS at a much reduced periodicity and/or transmit TSS only if some UL signal is received from the UE
• CSI-RS based with increased antenna port and density the increased density of CSI-RS can be viewed as a special form of TSS.
• Position RS based, "SIB-lite” transmission with more detailed information similar to system information block (SIB), or any form of a "beacon” signal with focused power on certain tones are also options.
• a special RACH format may be used for UEs that are capable of communication with other type nodes such as RRHs and relay UEs.
• a special RACH format may be used to indicate such capability of the UE.
• Network response may be different depending on the UE capability, for example, conveyed by Msg 1.
• Relay/CoMP capable UE may be handled by relay/RRH, while other UEs may be handled by the Macro.
• a similar format as current RACH may be used, but in Msg 3 capability information of UE may be revealed.
• UE's RACH procedure may be handled by Macro, then setup RRH/Relay connection.
• FIG. 10 illustrates example operations 1000 that may be performed by a wireless node utilizing a new RACH procedure.
• the wireless node may be a node belonging to a cluster of cells having a macro node and one or more other type nodes.
• the operations 1000 may begin, at 1002, by participating in at least a portion of a random access channel (RACH) procedure with a user equipment (UE).
• RACH random access channel
• UE user equipment
• the wireless node determines, based on capability information obtained during the portion of the RACH procedure, capability of the UE to detect and communicate with other type nodes in the cluster.
• FIG. 11 illustrates example operations 1100 that may be performed by a wireless node to detect TSS.
• the operations 1100 may be considered complementary to those shown in FIG. 10 and may be performed, for example, by a user equipment (UE) within a cluster of cells having a macro node and one or more other type nodes.
• UE user equipment
• the operations 1100 begin, at 1102, by participating in at least a portion of a random access channel (RACH) procedure with one of the other type nodes in the cluster.
• RACH random access channel
• the UE conveys, during the portion of the RACH procedure, capability of the UE to detect and communicate with other type nodes in the cluster.
• a UE may send Msg 1 to be received by all relay nodes.
• the relay nodes may convey detection as well as signal strength to Macro, and Macro decides on which relay to serve. If Msg 2 is responded from relay, it may have some delay.
• a new RACH format there are various design options, for example, including shortened format based on the low density requirement and the format may have a narrower bandwidth than 6 RBs.
• DSP digital signal processor
• ASIC application specific integrated circuit
• FPGA field programmable gate array
• a general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine.
• a processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
• a software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
• An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium.
• the storage medium may be integral to the processor.
• the processor and the storage medium may reside in an ASIC.
• the ASIC may reside in a user terminal.
• the processor and the storage medium may reside as discrete components in a user terminal.

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• 2013
  • 2013-04-25 US US13/870,523 patent/US9510212B2/en not_active Expired - Fee Related
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