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
  • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
  • H04L1/0072—Error control for data other than payload data, e.g. control data
  • H04L1/0073—Special arrangements for feedback channel
• • 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
  • H04L1/1607—Details of the supervisory signal
  • H04L1/1692—Physical properties of the supervisory signal, e.g. acknowledgement by energy bursts
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
  • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
  • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
  • H04L1/1829—Arrangements specially adapted for the receiver end
  • H04L1/1861—Physical mapping arrangements

Definitions

• Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on.
• Such networks which are usually multiple access networks, support communications for multiple users by sharing the available network resources.
• UTRAN UMTS Terrestrial Radio Access Network
• the UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP).
• UMTS Universal Mobile Telecommunications System
• 3GPP 3rd Generation Partnership Project
• the UMTS which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband- Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA).
• W-CDMA Wideband- Code Division Multiple Access
• TD-CDMA Time Division-Code Division Multiple Access
• TD-SCDMA Time Division-Synchronous Code Division Multiple Access
• the UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks.
• HSPA High Speed Packet Access
• FIG. 1 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.
• FIG. 2 is a block diagram conceptually illustrating an example of a telecommunications system.
• FIG. 3 is a conceptual diagram illustrating an example of an access network.
• FIG. 4 is a block diagram conceptually illustrating an example of a Node B in communication with a UE in a telecommunications system.
• FIG. 1 is a conceptual diagram illustrating an example of a hardware implementation for an apparatus 100 employing a processing system 114.
• the processing system 114 may be implemented with a bus architecture, represented generally by the bus 102.
• the bus 102 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 114 and the overall design constraints.
• the bus 102 links together various circuits including one or more processors, represented generally by the processor 104, and computer-readable media, represented generally by the computer- readable medium 106.
• the bus 102 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.
• a bus interface 108 provides an interface between the bus 102 and a transceiver 110.
• the transceiver 110 provides a means for communicating with various other apparatus over a transmission medium.
• a user interface 112 e.g., keypad, display, speaker, microphone, joystick
• keypad e.g., keypad, display, speaker, microphone, joystick
• the processor 104 is responsible for managing the bus 102 and general processing, including the execution of software stored on the computer-readable medium 106.
• the software when executed by the processor m ⁇ . tVi p processing system 114 to perform the various functions described infra for any particular apparatus.
• the computer-readable medium 106 may also be used for storing data that is manipulated by the processor 104 when executing software.
• a UMTS network includes three interacting domains: a Core Network (CN) 204, a UMTS Terrestrial Radio Access Network (UTRAN) 202, and User Equipment (UE) 210.
• CN Core Network
• UTRAN UMTS Terrestrial Radio Access Network
• UE User Equipment
• the UTRAN 202 provides various wireless services including telephony, video, data, messaging, broadcasts, and/or other services.
• the UTRAN 202 may include a plurality of Radio Network Subsystems (RNSs) such as an RNS 207, each controlled by a respective Radio Network Controller (RNC) such as an RNC 206.
• RNSs Radio Network Subsystems
• the UTRAN 202 may include any number of RNCs 206 and RNSs 207 in addition to the RNCs 206 and RNSs 207 illustrated herein.
• the RNC 206 is an apparatus responsible for, among other things, assigning, reconfiguring and releasing radio resources within the RNS 207.
• the RNC 206 may be interconnected to other RNCs (not shown) in the UTRAN 202 through various types of interfaces such as a direct physical connection, a virtual network, or the like, using any suitable transport network.
• Communication between a UE 210 and a Node B 208 may be considered as including a physical (PHY) layer and a medium access control (MAC) layer. Further, communication between a UE 210 and an RNC 206 by way of a respective Node B 208 may be considered as including a radio resource control (RRC) layer.
• RRC radio resource control
• the PHY layer may be considered layer 1; the MAC layer may be considered layer 2; and the RRC layer may be considered layer 3.
• Information hereinbelow utilizes terminology introduced in Radio Resource Control (RRC) Protocol Specification, 3GPP TS 25.331 v9.1.0, incorporated herein by reference.
• the geographic region covered by the SRNS 207 may be divided into a number of cells, with a radio transceiver apparatus serving each cell.
• a radio transceiver apparatus is commonly referred to as a Node B in UMTS applications, but may also be referred to by those skilled in the art as a base station (BS), a base transceiver station (BTS), a radio base station, a radio transceiver a tranc pp iver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), or some other suitable terminology.
• BS basic service set
• ESS extended service set
• AP access point
• three Node Bs 208 are shown in each SRNS 207; however, the SRNSs 207 may include any number of wireless Node Bs.
• the Node Bs 208 provide wireless access points to a core network (CN) 204 for any number of mobile apparatuses.
• a mobile apparatus include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a notebook, a netbook, a smartbook, a personal digital assistant (PDA), a satellite radio, a global positioning system (GPS) device, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device.
• SIP session initiation protocol
• PDA personal digital assistant
• GPS global positioning system
• multimedia device e.g., a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device.
• MP3 player digital audio player
• the mobile apparatus is commonly referred to as user equipment (UE) in UMTS applications, but may also be referred to by those skilled in the art as a mobile station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology.
• the UE 210 may further include a universal subscriber identity module (USIM) 211, which contains a user's subscription information to a network.
• USIM universal subscriber identity module
• DL downlink
• UL uplink
• the core network 204 interfaces with one or more access networks, such as the UTRAN 202.
• the core network 204 is a GSM core network.
• GSM Global System for Mobile communications
• the core network 204 includes a circuit-switched (CS) domain and a packet- switched (PS) domain.
• Some of the circuit-switched elements are a Mobile services Switching Centre (MSC), a Visitor location register (VLR) and a Gateway MSC.
• Packet- switched elements include a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN).
• Some network elements, like EIR, HLR, VLR and AuC may be shared by both of the circuit- switched and packet-switched domains.
• the core network 204 supports irrnit-switrVi p H services with a MSC 212 and a GMSC 214.
• the GMSC 214 may be referred to as a media gateway (MGW).
• MGW media gateway
• the MSC 212 is an apparatus that controls call setup, call routing, and UE mobility functions.
• the MSC 212 also includes a visitor location register (VLR) that contains subscriber-related information for the duration that a UE is in the coverage area of the MSC 212.
• VLR visitor location register
• the GMSC 214 provides a gateway through the MSC 212 for the UE to access a circuit- switched network 216.
• the core network 204 includes a home location register (HLR) 215 containing subscriber data, such as the data reflecting the details of the services to which a particular user has subscribed.
• HLR home location register
• the HLR is also associated with an authentication center (AuC) that contains subscriber-specific authentication data.
• AuC authentication center
• the GMSC 214 queries the HLR 215 to determine the UE's location and forwards the call to the particular MSC serving that location.
• the core network 204 also supports packet-data services with a serving GPRS support node (SGSN) 218 and a gateway GPRS support node (GGSN) 220.
• GPRS which stands for General Packet Radio Service, is designed to provide packet-data services at speeds higher than those available with standard circuit-switched data services.
• the GGSN 220 provides a connection for the UTRAN 202 to a packet- based network 222.
• the packet-based network 222 may be the Internet, a private data network, or some other suitable packet-based network.
• the primary function of the GGSN 220 is to provide the UEs 210 with packet-based network connectivity. Data packets may be transferred between the GGSN 220 and the UEs 210 through the SGSN 218, which performs primarily the same functions in the packet-based domain as the MSC 212 performs in the circuit- switched domain.
• the UMTS air interface is a spread spectrum Direct-Sequence Code Division
• the spread spectrum DS-CDMA spreads user data through multiplication by a sequence of pseudorandom bits called chips.
• the W- CDMA air interface for UMTS is based on such direct sequence spread spectrum technology and additionally calls for a frequency division duplexing (FDD).
• FDD uses a different carrier frequency for the uplink (UL) and downlink (DL) between a Node B 208 and a UE 210.
• TD-SCDMA Another air interface for UMTS that utilizes DS-CDMA, and uses time division duplexing.
• the multiple access wireless communication system includes multiple cellular regions (cells), including cells 302, 304, and 306, each of which may include one or more sectors.
• the multiple sectors can be formed by groups of antennas with each antenna responsible for communication with UEs in a portion of the cell. For example, in cell 302, antenna groups 312, 314, and 316 may each correspond to a different sector.
• antenna groups 318, 320, and 322 each correspond to a different sector.
• antenna groups 324, 326, and 328 each correspond to a different sector.
• the cells 302, 304 and 306 may include several wireless communication devices, e.g., User Equipment or UEs, which may be in communication with one or more sectors of each cell 302, 304 or 306.
• UEs 330 and 332 may be in communication with Node B 342
• UEs 334 and 336 may be in communication with Node B 344
• UEs 338 and 340 can be in communication with Node B 346.
• each Node B 342, 344, 346 is configured to provide an access point to a core network 204 (see FIG. 2) for all the UEs 330, 332, 334, 336, 338, 340 in the respective cells 302, 304, and 306.
• a serving cell change (SCC) or handover may occur in which communication with the UE 334 transitions from the cell 304, which may be referred to as the source cell, to cell 306, which may be referred to as the target cell.
• Management of the handover procedure may take place at the UE 334, at the Node Bs corresponding to the respective cells, at a radio network controller 206 (see FIG. 2), or at another suitable node in the wireless network.
• the UE 334 may monitor various parameters of the source cell 304 as well as various parameters of neighboring cells such as cells 306 and 302.
• the UE 334 may maintain communication with one or more of the neighboring cells. During this time, the UE 334 may maintain an Active Set, that is, a list of cells that the UE 334 is simultaneously connected to (i.e., the UTRA cells that are currently assigning a downlink dedicated physical channel DPCH or fractional downlink dedicated physical channel F-DPCH to the UE 334 may constitute the Active Set).
• an Active Set that is, a list of cells that the UE 334 is simultaneously connected to (i.e., the UTRA cells that are currently assigning a downlink dedicated physical channel DPCH or fractional downlink dedicated physical channel F-DPCH to the UE 334 may constitute the Active Set).
• the standard may vary depending on the particular telecommunications standard being deployed.
• the standard may include Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB).
• EV-DO and UMB are air interface standards promulgated by the 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access to mobile stations.
• 3GPP2 3rd Generation Partnership Project 2
• the standard may alternately be Universal Terrestrial Radio Access (UTRA) employing Wideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA; Global System for Mobile Communications (GSM) employing TDMA; and Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM employing OFDM A.
• UTRA, E-UTRA, UMTS, LTE, LTE Advanced, and GSM are described in documents from the 3GPP organization.
• CDMA2000 and UMB are described in documents from the 3GPP2 organization.
• the actual wireless communication standard and the multiple access technology employed will depend on the specific application and the overall design constraints imposed on the system.
• FIG. 4 is a block diagram of a Node B 410 in communication with a UE 450, where the Node B 410 may be the Node B 208 in FIG. 2, and the UE 450 may be the UE 210 in FIG. 2.
• a transmit processor 420 may receive data from a data source 412 and control signals from a controller/processor 440. The transmit processor 420 provides various signal processing functions for the data and control signals, as well as reference signals (e.g., pilot signals).
• the transmit processor 420 may provide cyclic redundancy check (CRC) codes for error detection, coding and interleaving to facilitate forward error correction (FEC), mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM), and the like), spreading with orthogonal variable spreading factors (OVSF), and multiplying with scrambling codes to produce a series of symbols.
• BPSK binary phase-shift keying
• QPSK quadrature phase-shift keying
• M-PSK M-phase-shift keying
• M-QAM M-quadrature amplitude modulation
• OVSF orthogonal variable spreading factors
• the channel estimates may be derived from a reference signal transmitted by the UE 450 or from feedback from the UE 450.
• the symbols generated thf » transmit processor 420 are provided to a transmit frame processor 430 to create a frame structure.
• the transmit frame processor 430 creates this frame structure by multiplexing the symbols with information from the controller/processor 440, resulting in a series of frames.
• the frames are then provided to a transmitter 432, which provides various signal conditioning functions including amplifying, filtering, and modulating the frames onto a carrier for downlink transmission over the wireless medium through antenna 434.
• the antenna 434 may include one or more antennas, for example, including beam steering bidirectional adaptive antenna arrays or other similar beam technologies.
• a receiver 454 receives the downlink transmission through an antenna 452 and processes the transmission to recover the information modulated onto the carrier.
• the information recovered by the receiver 454 is provided to a receive frame processor 460, which parses each frame, and provides information from the frames to a channel processor 494 and the data, control, and reference signals to a receive processor 470.
• the receive processor 470 then performs the inverse of the processing performed by the transmit processor 420 in the Node B 410. More specifically, the receive processor 470 descrambles and despreads the symbols, and then determines the most likely signal constellation points transmitted by the Node B 410 based on the modulation scheme. These soft decisions may be based on channel estimates computed by the channel processor 494.
• the soft decisions are then decoded and deinterleaved to recover the data, control, and reference signals.
• the CRC codes are then checked to determine whether the frames were successfully decoded.
• the data carried by the successfully decoded frames will then be provided to a data sink 472, which represents applications running in the UE 450 and/or various user interfaces (e.g., display).
• Control signals carried by successfully decoded frames will be provided to a controller/processor 490.
• the controller/processor 490 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.
• ACK acknowledgement
• NACK negative acknowledgement
• a transmit processor 480 receives data from a data source 478 and control signals from the controller/processor 490 and provides signals to a transmit processor 480.
• the data source 478 may represent applications running in the UE 450 and various user interfaces (e.g., keyboard).
• the transmit processor ARn nmviH p c various signal processing functions including CRC codes, coding and interleaving to facilitate FEC, mapping to signal constellations, spreading with OVSFs, and scrambling to produce a series of symbols.
• Channel estimates may be used to select the appropriate coding, modulation, spreading, and/or scrambling schemes.
• the symbols produced by the transmit processor 480 will be provided to a transmit frame processor 482 to create a frame structure.
• the transmit frame processor 482 creates this frame structure by multiplexing the symbols with information from the controller/processor 490, resulting in a series of frames.
• the frames are then provided to a transmitter 456, which provides various signal conditioning functions including amplification, filtering, and modulating the frames onto a carrier for uplink transmission over the wireless medium through the antenna 452.
• the uplink transmission is processed at the Node B 410 in a manner similar to that described in connection with the receiver function at the UE 450.
• a receiver 435 receives the uplink transmission through the antenna 434 and processes the transmission to recover the information modulated onto the carrier.
• the information recovered by the receiver 435 is provided to a receive frame processor 436, which parses each frame, and provides information from the frames to the channel processor 444 and the data, control, and reference signals to a receive processor 438.
• the receive processor 438 performs the inverse of the processing performed by the transmit processor 480 in the UE 450.
• the data and control signals carried by the successfully decoded frames may then be provided to a data sink 439 and the controller/processor, respectively. If some of the frames were unsuccessfully decoded by the receive processor, the controller/processor 440 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.
• ACK acknowledgement
• NACK negative acknowledgement
• the controller/processors 440 and 490 may be used to direct the operation at the Node B 410 and the UE 450, respectively.
• the controller/processors 440 and 490 may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions.
• the computer readable media of memories 442 and 492 may store data and software for the Node B 410 and the UE 450, respectively.
• a scheduler/processor 446 at the Node B 410 may be used to allocate resources to the UEs and schedule downlink and/or uplink transmissions for the UEs.
• R99 packets transmitted over time durations (TTIs) of 10ms, 20ms, 40ms or 80ms are often decodable by the receiver prior to reception of the entire packet.
• TTIs time durations
• Substantial system capacity gains are possible if the transmitter stops the packet transmission as soon as it is made aware that the receiver has succeeded in decoding the packet early.
• realizing these capacity gains requires a fast and reliable feedback channel on which the receiver can inform the transmitter of the success (Ack) or failure (Nack) of its early decoding attempts.
• one design option for sending Ack/Nack on the uplink is to carry it on the uplink DPCCH, by replacing the TPC field by an on/off keyed Ack/Nack field in a subset of slots (eg, every alternate slot).
• the Ack may need a higher transmit power than the TPC.
• One option is to boost the Ack symbols by a pre-configured power offset relative to the TPC symbols. In some cases, selective boosting of certain symbols within the slot could lead to harmful RF impairments. To avoid this, the entire DPCCH slot in which an Ack has to be sent can be boosted in power relative to the power level at which it would have been transmitted as per the current R99 specification.
• this power boost only applies for the slots in which 'Ack' has to be sent, and not for slots where 'Nack' is sent or for slots that are not reserved for Ack/Nack transmission.
• the NodeB receiver algorithms that rely on DPCCH symbol power measurements can be appropriately modified to account for this known power boost once the Ack/Nack detector detects an Ack in a particular slot.
• Ack/Nack is sent on a different channel that uses a separate spreading code. This has the advantage of keeping the uplink power-control rate undisturbed, at the expense of using an additional code resource.
• the new code resource need not be exclusively for the Ack/Nack channel; other already existing control channels may be modified to accommodate the Ack/Nack channel.
• the encoding of the E-DPCCH or the HS-DPCCH could be modified to allow inclusion of a bit indicating Ack/Nack.
• the above discussed methods and systems may reside in the UE receiver and/or Node B transmitter. Further, the implementation of the present invention may involve a standards change.
• TD-SCDMA High Speed Downlink Packet Access
• HSDPA High Speed Downlink Packet Access
• HSUPA High Speed Uplink Packet Access
• HSPA+ High Speed Packet Access Plus
• LTE Long Term Evolution
• LTE-A LTE-Advanced
• CDMA2000 Evolution-Data Optimized
• UMB Ultra Mobile Broadband
• IEEE 802.11 Wi-Fi
• IEEE 802.16 WiMAX
• IEEE 802.20 Ultra- Wideband
• Bluetooth Bluetooth
• the actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.
• processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure.
• DSPs digital signal processors
• FPGAs field programmable gate arrays
• PLDs programmable logic devices
• state machines gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure.
• One or more processors in the processing system may execute software.
• Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.
• the software may reside on a computer-readable medium.
• the computer-readable medium may be a non-transitory computer-readable medium.
• a non-transitory computer-readable medium includes, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., compact disk (CD), digital versatile disk (DVD)), a smart card, a flash memory device (e.g., card, stick, key drive), random access memory (RAM), read only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), a register, a removable disk, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer.
• a magnetic storage device e.g., hard disk, floppy disk, magnetic strip
• an optical disk e.g., compact disk (CD), digital versatile disk (DVD)
• a smart card e.g., a flash memory device (e.g., card, stick, key drive), random access memory (RAM), read only memory (ROM), programmable ROM
• the computer-readable medium may also include, by way of example, a carrier wave, a transmission line, and any other suitable medium for transmitting software and/or instructions that may be accessed and read by a computer.
• the computer-readable medium may be resident in the processing system, external to the processing system, or distributed across multiple entities including the processing system.
• the computer-readable medium may be embodied in a computer-program product.
• a computer- program product may include a computer-readable medium in packaging materials.
• R99 packets transmitted over time durations (TTIs) of 10ms, 20ms, 40ms or 80ms are often decodable by the receiver prior to reception of the entire packet.
• TTIs time durations
• Substantial system capacity gains are possible if the transmitter stops the packet transmission as soon as it is made aware that the receiver has succeeded in decoding the packet early.
• realizing these capacity gains requires a fast and reliable feedback channel on which the receiver can inform the transmitter of the success (Ack) or failure (Nack) of its early decoding attempts.
• one design option for sending Ack/Nack on the uplink is to carry it on the uplink DPCCH, by replacing the TPC field by an on/off keyed Ack/Nack field in a subset of slots (eg, every alternate slot).
• the Ack may need a higher transmit power than the TPC.
• One option is to boost the Ack symbols by a pre-configured power offset relative to the TPC symbols. In some cases, selective boosting of certain symbols within the slot could lead to harmful RF impairments. To avoid this, the entire DPCCH slot in which an Ack has to be sent can be boosted in power relative to the power level at which it would have been transmitted as per the current R99 specification.
• this power boost only applies for the slots in which 'Ack' has to be sent, and not for slots where 'Nack' is sent or for slots that are not reserved for Ack/Nack transmission.
• the NodeB receiver algorithms that rely on DPCCH symbol power measurements can be appropriately modified to account for this known power boost once the Ack/Nack detector detects an Ack in a particular slot.
• Replacing TPC by Ack in selected uplink slots has the impact of reducing the power- control rate for the downlink. Similar to the case explained in [2], negative performance impacts from this can be mitigated by optimizing the configuration parameters such as power-control stepsize and receiver algorithm parameters such as SNR estimation filter coefficients, to account for the reduced power-control rate. Also as in [2], this impact could be reduced by an alternative design that replaces only a part of the TPC symbols by Ack/Nack symbols in the slots reserved for sending Ack/Nack; for example, I-Q multiplexing of TPC and Ack/Nack symbols.
• Ack channel design is a CDM approach, in which the Ack/Nack is sent on a different channel that uses a separate spreading code. This has the advantage of keeping the uplink power-control rate undisturbed, at the expense of using an additional code resource.
• the new code resource need not be exclusively for the Ack/Nack channel; other already existing control channels may be modified to accommodate the Ack/Nack channel.
• the encoding of the E- DPCCH or the HS-DPCCH could be modified to allow inclusion of a bit indicating Ack/Nack.
• o UE receiver, NodeB: Transmitter.
• OVSF code channel is the one used by E-DPCCH or HS-DPCCH, whose encoding is modified to allow inclusion of a bit indicating the Ack/Nack information.
• R99 packets transmitted over time durations (TTIs) of 10ms, 20ms, 40ms or 80ms are often decodable by the receiver prior to reception of the entire packet.
• TTIs time durations
• Substantial system capacity gains are possible if the transmitter stops the packet transmission as soon as it is made aware that the receiver has succeeded in decoding the packet early.
• realizing these capacity gains requires a fast and reliable feedback channel on which the receiver can inform the transmitter of the success (Ack) or failure (Nack) of its early decoding attempts.
• the Ack channel is transmitted using on-off keying to reduce its power requirement.
• the 'off transmissions represent negative acknowledgment (Nack) until an 'on' transmission is sent at a pre- configured power to represent positive acknowledgment (Ack).
• 'off transmissions are sent after an 'on' transmission until the end of the packet.
• the Ack may be sent multiple times per packet, to increase the reliability of its reception.
• the Ack may be repeated only if it is determined that the original Ack transmission was not received correctly. Such a determination can be made by continued monitoring of the energy of the received packet even after it has been decoded, in order to determine whether the transmitter has stopped the packet transmission in response to the Ack. In all these approaches, a decision could also be made to avoid sending an Ack even though the packet was decoded, based on other criteria.
• Examples of such criteria are (a) if the transmitter sending the Ack is close to its maximum power limit, or (b) if the packet only decoded very near to its completion, so that the amount of time for which the packet transmission could be stopped (after accounting for the delay in receiving the Ack) would be very small or zero.
• the receiver subsystem detecting the Ack/Nack need not be based only on energy detection; it could also employ coherent demodulation using channel estimates that are already available and in use for demodulation of other control and data channels.
• One approach for the Ack channel sent on the downlink to acknowledge packets received on the uplink is a TDM design in which certain time durations on the DL R99 DPCH channel are reserved for sending the Ack/Nack information.
• the time durations reserved could be a subset of those normally used to send ULTPC bits, which are sent every slot as per the current specification.
• every alternate slot could be reserved for Ack/Nack instead of ULTPC. This has the impact of reducing the uplink power-control rate by a factor of half, which may affect the uplink performance. The uplink performance impact may be reduced by re- optimizations that account for the reduced power-control rate.
• These optimizations include configuration parameters such as the power-control step size as well as uplink receiver algorithms and their parameters, such as the filter coefficients for the power- control SNR estimation filter.
• the ULTPC bits may also be used by the downlink receiver for other purposes, such as SNR estimation for downlink power control, so reducing the ULTPC bit rate could impact these other uses as well. Again, these impacts could be reduced by re-optimizing configuration parameters such as the downlink power control stepsize, and downlink receiver parameters such as the downlink SNR estimation filter coefficients, to account for the reduced ULTPC bit rate.
• the ULTPC bit rate reduction impacts could also be reduced by reserving a smaller subset of the ULTPC bit positions for the Ack/Nack.
• the number of ULTPC bits per slot is always even, so another option would be use half of them for ULTPC and the other half for Ack/Nack.
• the ULTPC and the Ack can be I-Q multiplexed in each slot. This preserves the uplink power-control rate, but impacts the ULTPC demodulation performance instead. This impact can be eliminated by appropriately increasing the ULTPC transmit power to compensate for the reduced number of ULTPC bits.
• This scheme does not affect the ULTPC bit decoding performance when a Nack has to be sent, due to the use of on-off keying.
• receiver imperfections such as channel estimation errors, frequency offsets and I-Q phase imbalances may cause degradation in the ULTPC bit demodulation.
• This degradation may be acceptable since it only happens infrequently, as Ack is sent only once or a few times per packet. This degradation may be further reduced by declaring a ULTPC bit erasure whenever an Ack is detected. Another way to reduce this degradation is to transmit the ULTPC bit with a higher power in the slots where Ack needs to be sent, as compared to the power used in slots where Nack needs to be sent. The difference between these powers is known to the receiver and can thus be accounted for in other algorithms that may use the ULTPC bits (eg, SNR estimation for downlink power control).
• the above approaches may be described as creating a new slot-format that allows the Ack transmission, and defining the subset of slots that will use the newly created slot-format.
• Ack channel design is a CDM approach, in which the Ack/Nack is sent on a different channel that uses a separate spreading code. This has the advantage of keeping the uplink power-control rate undisturbed, at the expense of using an additional code resource.
• the new code resource need not be exclusively for the Ack/Nack channel; other already existing control channels may be modified to accommodate the Ack/Nack channel. For example, some bit positions on the F-DPCH, or some signature sequences on E-HICH or E-RGCH can be reserved for transmitting the Ack/Nack information.
• o UE receiver, NodeB: Transmitter.
• R99 packets transmitted over time durations (TTIs) of 10ms, 20ms, 40ms or 80ms are often decodable by the receiver prior to reception of the entire packet. Substantial system capacity gains are possible if the transmitter stops the packet transmission as soon as it is made aware that the receiver has succeeded in decoding the packet early. Receiver power consumption savings are also possible because appropriate receiver subsystems can be powered down from the time of successful early decoding until the end of the packet duration. Transmissions on both uplink and downlink include both control and data packets, and control information on one link could impact the transmission and performance of the other link. Hence, an appropriate control logic is required to determine which transmissions can be stopped and at what time relative to the end of the packet, so as to maximize the power savings and capacity gains from early termination while minimizing its unwanted side-effects.
• TTIs time durations
• the invention consists of a set of rules to be applied by both the UE and NodeB transceivers in response to reception of acknowledgements (Ack) of early decoding of packets.
• the underlying principle is as follows: Denote the transceiver functions at the two ends of the communications link by UE-Tx, UE-Rx, NodeB-Tx, and NodeB- Rx. If UE-Rx receives an Ack from NodeB-Tx for a packet that is being transmitted by UE-Tx, then UE-Tx must carry out the following actions:
• the UE-Rx must initially try to decode the data packet sent by NodeB-Tx as well as monitor the control information (power- control and Ack/Nack for UE-Tx transmissions).
• the data packet decoding module can be powered down (eg, to save on current consumption) from the time the packet is decoded until the end of the packet.
• the modules decoding the power-control and Ack/Nack information can be powered down as soon as an Ack is received.
• the implementation of the above rules will depend on the encoding/modulation scheme used to transmit the control information (power-control and Ack/Nack).
• the Ack/Nack is usually transmitted with on-off keying.
• the transmissions both before and after the Ack is sent are identical zero-power transmissions (DTX), except that the ones before the Ack have the interpretation of Nack (i.e., packet was not received), while the ones after the Ack (until the end of the packet) are simply ignored by the receiver since it has already received the Ack.
• DTX zero-power transmissions
• control information (TPC bits that control downlink power, and TFCI) is carried on the DPCCH, which also carries pilots to aid demodulation of control and data channels.
• the uplink data packets are carried on DPDCH which uses a different spreading code than DPCCH.
• the UE-Tx can stop the DPDCH transmission as soon as it receives an Ack from the Node-B on the downlink.
• the DPCCH is no longer required as a phase reference for demodulation of DPDCH, but is still required to carry control information, and the phase reference needed to demodulate this control information.
• the control information carried consists of DLTPC bits that control the downlink power, Ack/Nack indication for the downlink packet, and the TFCI indicating the type of packet transmitted on the uplink.
• the TFCI is no longer needed as the uplink packet has already been acknowledged.
• the remaining control information could be sent at a reduced rate, hence the rate of DPCCH transmissions can be reduced, resulting in reduced interference to other users and thus, to gains in system capacity.
• one method to allow UE-Tx to transmit the Ack/Nack information is to reserve certain slots in which the DLTPC will be replaced by Ack, thus reducing the downlink power-control rate. For example, every alternate slot can be reserved for Ack/Nack instead of DLTPC.
• the DPCCH may be transmitted as in the current specification, carrying pilots, DLTPC and TFCI.
• the pilots are not necessary due to the on-off nature of the Ack/Nack signalling which can be demodulated using an energy detector, and the TFCI is also not necessary as the uplink packet has been acknowledged.
• a Nack could be sent in these reserved slots by suppressing the DPCCH transmission altogether, resulting in system capacity gains.
• the current DPCCH format could be used with DLTPC replaced by Ack, or a new format could be used.
• new slot formats are (a) with only the Ack symbol present and all other symbols (pilot and TFCI) being replaced by DTX, (b) using the format of the current specification with TPC replaced by Ack and TFCI either DTXed, or replaced by a known pilot, or sent as in the current specification, in which case it can still be used as a pilot at the receiver since the receiver has already decoded the TFCI.
• the DPCCH can then be completely DTXed as both the uplink and downlink packets have been decoded.
• the method consists of
• the transceiver unit is an R99 UE
• the data transmissions are carried on the uplink DPDCH channel
• the control transmissions are the pilots, TPC and TFCI carried on the uplink DPCCH channel.
• the other (non-TPC) symbols are either left unchanged from the current specification, or modified, or DTXed when Ack is sent.
• the pilots may be DTXed or left unchanged.
• the TFCI may be DTXed, left unchanged, or replaced by a known pilot.
• the TFCI is already known to the receiver in this case, and hence can be used as a pilot even if it is left unchanged.

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• 2012
  • 2012-02-27 WO PCT/CN2012/071676 patent/WO2013127057A1/en not_active Ceased
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• 2013
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