WO2013127057A1

WO2013127057A1 - Ack channel design for early termination of r99 downlink traffic

Info

Publication number: WO2013127057A1
Application number: PCT/CN2012/071676
Authority: WO
Inventors: Sharad Deepak Sambhwani; Sony John Akkarakaran; Jiye Liang; Yin Huang
Original assignee: Qualcomm Incorporated
Priority date: 2012-02-27
Filing date: 2012-02-27
Publication date: 2013-09-06
Also published as: IN2014MN01719A; WO2013127091A1

Abstract

A method of transmitting acknowledgements on certain slots of the R99 uplink DPCCH channel for traffic packets sent on the R99 downlink channel, by replacing the TPC bits by Ack bits transmitted with on-off keying, applying a pre-configured boost to the transmit power of the entire slot in which an Ack has to be transmitted, or to only the Ack symbol in that slot, and not applying any boost to slots not reserved for Ack/Nack transmission or slots in which a Nack has to be sent; and modifying the NodeB receiver algorithms to account for the extra power boost once the Ack/Nack detector detects that an Ack has been transmitted in a given slot.

Description

ACK CHANNEL DESIGN FOR EARLY TERMINATION OF R99 DOWNLINK TRAFFIC

BACKGROUND

[0001] 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. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). 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). 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). 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.

[0002] As the demand for mobile broadband access continues to increase, research and development continue to advance the UMTS technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.

SUMMARY

[0003] These and other aspects of the invention will become more fully understood upon a review of the detailed description, which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system. [0005] FIG. 2 is a block diagram conceptually illustrating an example of a telecommunications system.

[0006] FIG. 3 is a conceptual diagram illustrating an example of an access network.

[0007] FIG. 4 is a block diagram conceptually illustrating an example of a Node B in communication with a UE in a telecommunications system.

DETAILED DESCRIPTION

[0008] The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

[0009] FIG. 1 is a conceptual diagram illustrating an example of a hardware implementation for an apparatus 100 employing a processing system 114. In this example, 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. Depending upon the nature of the apparatus, a user interface 112 (e.g., keypad, display, speaker, microphone, joystick) may also be provided.

[0010] 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.

[0011] The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards. By way of example and without limitation, the aspects of the present disclosure illustrated in FIG. 2 are presented with reference to a UMTS system 200 employing a W-CDMA air interface. 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. In this example, 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. Here, 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.

[0012] 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. In the instant specification, 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.

[0013] 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^ppiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), or some other suitable terminology. For clarity, 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. Examples of 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. 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. In a UMTS system, the UE 210 may further include a universal subscriber identity module (USIM) 211, which contains a user's subscription information to a network. For illustrative purposes, one UE 210 is shown in communication with a number of the Node Bs 208. The downlink (DL), also called the forward link, refers to the communication link from a Node B 208 to a UE 210, and the uplink (UL), also called the reverse link, refers to the communication link from a UE 210 to a Node B 208.

[0014] The core network 204 interfaces with one or more access networks, such as the UTRAN 202. As shown, the core network 204 is a GSM core network. However, as those skilled in the art will recognize, the various concepts presented throughout this disclosure may be implemented in a RAN, or other suitable access network, to provide UEs with access to types of core networks other than GSM networks.

[0015] 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. In the illustrated example, the core network 204 supports irrnit-switrVi^pH services with a MSC 212 and a GMSC 214. In some applications, the GMSC 214 may be referred to as a media gateway (MGW). One or more RNCs, such as the RNC 206, may be connected to the MSC 212. 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. 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. The HLR is also associated with an authentication center (AuC) that contains subscriber- specific authentication data. When a call is received for a particular UE, the GMSC 214 queries the HLR 215 to determine the UE's location and forwards the call to the particular MSC serving that location.

[0016] 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.

[0017] The UMTS air interface is a spread spectrum Direct-Sequence Code Division

Multiple Access (DS-CDMA) system. 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. Another air interface for UMTS that utilizes DS-CDMA, and uses time division duplexing, is the TD-SCDMA air interface. Those skilled in the art will recognize that although various examples described herein may refer to a WCDMA air interface, the underlying principles are equally applicable to a TD- SCDMA air interface.

[0018] Referring to Fig. 3, an access network 300 in a UTRAN architecture is illustrated. 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. In cell 304, antenna groups 318, 320, and 322 each correspond to a different sector. In cell 306, 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. For example, UEs 330 and 332 may be in communication with Node B 342, UEs 334 and 336 may be in communication with Node B 344, and UEs 338 and 340 can be in communication with Node B 346. Here, 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.

[0019] As the UE 334 moves from the illustrated location in cell 304 into cell 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. For example, during a call with the source cell 304, or at any other time, 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. Further, depending on the quality of these parameters, 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). [0020] The modulation and multiple access scheme employed by the access network

300 may vary depending on the particular telecommunications standard being deployed. By way of example, 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. 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.

[0021] 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. In the downlink communication, 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). For example, 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. Channel estimates from a channel processor 444 may be used by a controller/processor 440 to determine the coding, modulation, spreading, and/or scrambling schemes for the transmit processor 420. These 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.

[0022] At the UE 450, 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. When frames are unsuccessfully decoded by the receiver processor 470, the controller/processor 490 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.

[0023] In the uplink, data from a data source 478 and control signals from the controller/processor 490 are provided to a transmit processor 480. The data source 478 may represent applications running in the UE 450 and various user interfaces (e.g., keyboard). Similar to the functionality described in connection with the downlink transmission by the Node B 410, the transmit processor ARn nmviH^pc 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, derived by the channel processor 494 from a reference signal transmitted by the Node B 410 or from feedback contained in the midamble transmitted by the Node B 410, 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.

[0024] 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.

[0025] The controller/processors 440 and 490 may be used to direct the operation at the Node B 410 and the UE 450, respectively. For example, 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.

[0026] Examples of the invention are shown in the appendices.

[0027] 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. However, 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.

[0028] International Application No. PCT/CN2009/075179 (WO2011/063569) entitled

"Increasing Capacity in Wireless Communications," (hereinafter referred to as [1]), which is hereby incorporated by reference herein, outlined TDM and CDM approaches to design of the

Ack channel. In U.S. Provisional Application No. (Attorney Docket No.

121588P1) entitled "Ack channel design for early termination of R99 uplink traffic," filed February 24, 2012, (hereinafter referred to as [2]) which is hereby incorporated by reference herein, detailed design principles and options were presented, some specific to the Ack for uplink traffic, and many equally applicable to both uplink and downlink Ack channels. In

International Application No. (Attorney Docket No. 121601P1) entitled

"Frame Early Termination of UL transmissions on dedicated channel," filed February 24, 2012 in China, (hereinafter referred to as [3]) which is hereby incorporated by reference herein, some specific design options were considered for the Ack channel for downlink traffic, in the context of defining algorithms for early termination of transmissions in response to Acks. Here we present further design options and solutions to some issues that arise in their implementations .

[0029] As explained in [3], 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). To be received reliably, 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. Note that 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.

[0030] 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.

[0031] Another approach for the 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. However, 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, the encoding of the E-DPCCH or the HS-DPCCH could be modified to allow inclusion of a bit indicating Ack/Nack.

[0032] 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.

[0033] Several aspects of a telecommunications system have been presented with reference to a W-CDMA system. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards.

[0034] By way of example, various aspects may be extended to other UMTS systems such as TD-SCDMA, High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), High Speed Packet Access Plus (HSPA+) and TD- CDMA. Various aspects may also be extended to systems employing Long Term Evolution (LTE) (in FDD, TDD, or both modes), LTE-Advanced (LTE-A) (in FDD, TDD, or both modes), CDMA2000, Evolution-Data Optimized (EV-DO), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra- Wideband (UWB), Bluetooth, and/or other suitable systems. 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. [0035] In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a "processing system" that includes one or more processors. Examples of 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. 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. 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. By way of example, a computer- program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.

[0036] It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Ba ^™^m H^si an preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented unless specifically recited therein.

[0037] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more." Unless specifically stated otherwise, the term "some" refers to one or more. A phrase referring to "at least one of a list of items refers to any combination of those items, including single members. As an example, "at least one of: a, b, or c" is intended to cover: a; b; c; a and b; a and c; b and c; and a, b and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase "means for" or, in the case of a method claim, the element is recited using the phrase "step for."

[0038] Ack channel design for early termination of R99 downlink traffic (Sharad

Sambhwani, Sony Akkarakaran, Jiye Liang, Yin Huang)

Description of the Problem

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. However, 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. Description of the Invention

Previous work [1] has outlined TDM and CDM approaches to design of the Ack channel. In [2], detailed design principles and options were presented, some specific to the Ack for uplink traffic, and many equally applicable to both uplink and downlink Ack channels. In [3], some specific design options were considered for the Ack channel for downlink traffic, in the context of defining algorithms for early termination of transmissions in response to Acks. Here we present further design options and solutions to some issues that arise in their implementations.

As explained in [3], 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). To be received reliably, 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. Note that 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.

Another approach for the 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. However, 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, the encoding of the E- DPCCH or the HS-DPCCH could be modified to allow inclusion of a bit indicating Ack/Nack.

Detectability

• Where does this invention reside?

o UE: receiver, NodeB: Transmitter.

• How would you detect if someone infringes?

o Involves standards change.

• How easy is it to create a design work-around? If it is easy and new, please consider including this in your invention.

o Potential work-arounds included in the invention.

Claim Recommendations

• 1) A method of transmitting acknowledgements on certain slots of the R99 uplink DPCCH channel for traffic packets sent on the R99 downlink channel, by

o Replacing the TPC bits by Ack bits transmitted with on-off keying, o Applying a pre-configured boost to the transmit power of the entire slot in which an Ack has to be transmitted, or to only the Ack symbol in that slot, and not applying any boost to slots not reserved for Ack/Nack transmission or slots in which a Nack has to be sent, o Modifying the NodeB receiver algorithms to account for the extra power boost once the Ack/Nack detector detects that an Ack has been transmitted in a given slot.

• 2) A method of transmitting acknowledgements on the R99 uplink channel for traffic packets sent on the R99 downlink channel, by sending the Ack/Nack information on an OVSF code channel distinct from that used by the uplink DPCCH or DPDCH.

• 3) The method of claim 2), where the 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.

References

• [1] "Increasing Capacity in Wireless Communications", Docket No. 100147, Qualcomm.

• [2] "Ack channel design for early termination of R99 uplink traffic", Qualcomm

• [3] "Frame Early Termination of UL transmissions on dedicated channel", Qualcomm

Ack channel design for early termination of R99 uplink traffic (Sony

Akkarakaran, Sharad Sambhwani)

Description of the Problem

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. However, 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.

Description of the Invention

Previous work [1] has outlined TDM and CDM approaches to design of the Ack channel. Here we (a) present detailed implementation options for the TDM and CDM approaches, (b) present an alternative approach involving I-Q multiplexing, and (c) present solutions to some issues that arise in these implementations in the context of R99 transmissions. As shown in [1], the Ack channel is transmitted using on-off keying to reduce its power requirement. The 'off transmissions (sent with zero power) represent negative acknowledgment (Nack) until an 'on' transmission is sent at a pre- configured power to represent positive acknowledgment (Ack). In one approach, 'off transmissions are sent after an 'on' transmission until the end of the packet. These 'off transmissions do not signify Nack, but are rather intended to be ignored since the packet has already been acknowledged. In another approach, the Ack may be sent multiple times per packet, to increase the reliability of its reception. In yet another approach, 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. Note that although the Ack transmission uses on-off signaling, 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. For example, 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. As an example, 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. This creates nonuniform rate uplink power control with a higher average power-control rate than that obtained by reserving every alternate slot ULTPC for Ack/Nack. This trades off uplink power-control rate for Ack delay, since fewer Ack opportunities implies that the receiver may have to wait longer before it can send the Ack.

In the current specification, 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. For example, 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. However, when Ack has to be sent, 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).

In general 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.

Another approach for the 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. However, 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.

Detectability

• Where does this invention reside?

o UE: receiver, NodeB: Transmitter.

• How would you detect if someone infringes?

o Involves standards change.

o Potential work-arounds included in the invention.

Claim Recommendations

1) A method of transmitting acknowledgements on R99 downlink channel for traffic packets sent on the R99 uplink channel, by

o creating a slot format that includes positions for Ack bits, o defining a subset of slots in which the new slot format thus created will be used,

o pre-configuring the power-level at which the Ack bits will be sent in this new slot format

2) The method of claim 1), where the new slot format replaces all TPC bits of the previously used slot format by Ack bits

3) The method of claim 1) where the new slot format replaces a subset of the TPC bits of the previously used slot format by Ack bits

4) The method of claim 3) where the subset of the TPC bits replaced by Ack bits consists of half of the bits, which are then I-Q multiplexed with the remaining half of the TPC bits. 5) The method of claim 3), where the transmit power offset between the TPC bits and the DPDCH bits may be different in the slots where Ack is transmitted, as compared to the slots in which Nack is transmitted, and the difference in these offsets is pre-configured and known to the receiver.

6) The method of claim 3), where the receiver subsystem that demodulates the TPC bits declares an erasure if an Ack is detected in the same slot.

7) The method of claim 1) where the new slot format is used every alternate slot

8) The method of claim 1) where the new slot format is used once every third slot, or less frequently.

9) A method of transmitting acknowledgements on R99 downlink channel for traffic packets sent on the R99 uplink channel, by using resources of another existing downlink control channel.

10) The method of claim 9) where the existing downlink control channel is the F-DPCH and a subset of the F-DPCH bit positions are reserved for the Ack channel

11) The method of claim 9) where the existing downlink channel is the E- HICH or E-RGCH, and a pre-configured signature sequence is reserved for the Ack channel.

12) The method of claim 1) where the Ack is sent only at most once per packet, after the packet decodes successfully

13) The method of claim 1) where the Ack is sent multiple times for the same packet after it decodes successfully to increase its reliability

14) The method of claim 13) where the decision to repeat the Ack is based on an assessment of whether the previous Ack was received, by monitoring the received packet energy to determine whether the transmitter has stopped transmitting the packet in response to the Ack.

15) The method of claim 1), where transmission of Ack may be skipped even though the packet was decoded, based on other criteria

16) The method of claim 15), where the other criterion is the condition when there is insufficient transmit power available to transmit the Ack,

17) The method of claim 15), where the other criterion is the condition that there will be only a small duration of time for which the transmission of the packet that is being acknowledged can be stopped, after accounting for the time that the packet was decoded and the delay in reception of the Ack.

References

^■ [1] "Increasing Capacity in Wireless Communications", Docket No. 100147, Qualcomm.

[3] Frame Early Termination of UL transmissions on dedicated channel

(Jiye Liang, Yin Huang, Sharad Sambhwani, Sony Akarrakaran)

Description of the Problem

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.

Description of the Invention

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:

(a) Stop transmitting the portion of its usual transmitted waveform that is used by NodeB-Rx exclusively to decode the packet which was acknowledged (b) Continue to transmit other portions of the transmit waveform that NodeB-Rx needs to demodulate for other uses, such as control of NodeB-Tx transmissions (eg, power-control and Ack/Nack for information packet sent by NodeB-Tx),

(c) Stop transmission of these residual portions mentioned in (b) once their use ends. Specifically, once UE-Rx has decoded the packet that NodeB-Tx has been transmitting to it, UE-Tx transmits an Ack for this packet and then a tight power- control for NodeB-Tx transmissions is no longer necessary for the duration of this packet, hence all UE-Tx transmissions of commands used for this power-control can be stopped. Similarly, the Ack/Nack transmission is also stopped since the packet has already been acknowledged by an Ack.

It is readily seen that the roles of UE and NodeB are interchangeable here; the above rules also apply if UE and NodeB are interchanged throughout the description of the rules. Similarly, the rules to be applied by the receivers are readily inferred from the above rules describing the transmitters: 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. These rules describe the earliest point of time at which the various modules can be powered down; however, implementation constraints in practical receivers may make it beneficial to power down at a later time, or in some cases, not power down at all.

The implementation of the above rules will depend on the encoding/modulation scheme used to transmit the control information (power-control and Ack/Nack). For example, the Ack/Nack is usually transmitted with on-off keying. In this case, 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.

In the context of R99 uplink, the current specification states that 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. In this case, 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. As an example, 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. In the slots that have not been thus reserved, the DPCCH may be transmitted as in the current specification, carrying pilots, DLTPC and TFCI. In the reserved slots however, 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. Thus, a Nack could be sent in these reserved slots by suppressing the DPCCH transmission altogether, resulting in system capacity gains. To send an Ack in the reserved slots, the current DPCCH format could be used with DLTPC replaced by Ack, or a new format could be used. Examples of 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. Once the Ack has been sent, the DPCCH can then be completely DTXed as both the uplink and downlink packets have been decoded.

Detectability

• Where does this invention reside?

o Transmitter and receiver of both UE and NodeB

• How would you detect if someone infringes? o Involves standards change.

o Potential work-arounds included in the invention.

Claim Recommendations

1) A method for determining when transmissions of data and control information from a transceiver unit can be terminated prior to complete transmission of the data packets, in a system in which the receivers in the transceiver units attempt to decode the data packets prior to their complete receiption and send acknowledgment feedback about the success or failure of these decode attempts. The method consists of

o Terminating the data transmission as well as the portion of the control transmission that is only required to enable decoding of the data transmission, as soon as the data transmission is acknowledged by its intended receiver

o Terminating the entire transmission (both data and control) as soon as both the following have occurred:

^■ The data transmission has already been terminated

^■ The packet transmissions occuring during the same time interval that are intended for reception by the receiver within the transceiver unit have been received and an acknowledgment has been sent to indicate the reception.

2) The method of claim 1), where the transceiver unit is an R99 UE, the data transmissions are carried on the uplink DPDCH channel and the control transmissions are the pilots, TPC and TFCI carried on the uplink DPCCH channel.

3) The method of claim 2), where the UE acknowledges downlink data packets from the NodeB by sending Ack/Nack in a subset of slots reserved for this purpose; for example, every alternate slot.

4) The method of claim 3), where, in the slots reserved for Ack/Nack, the TPC symbols carried on the DPCCH are replaced by on-off keyed Ack/Nack symbols,

if the uplink DPDCH packet has not yet been acknowledged, the other symbols (besides TPC) are unchanged,

if the uplink DPDCH packet has already been acknowledged,

^■ the other symbols (besides TPC) are DTXed (i.e., transmitted with zero power) when Nack is sent, implying that the entire DPCCH is DTXed in such slots,

^■ the other (non-TPC) symbols are either left unchanged from the current specification, or modified, or DTXed when Ack is sent. Specifically, 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.

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A method of transmitting acknowledgements on certain slots of the R99 uplink DPCCH channel for traffic packets sent on the R99 downlink channel, by

^■ Replacing the TPC bits by Ack bits transmitted with on-off keying,

^■ Applying a pre-configured boost to the transmit power of the entire slot in which an Ack has to be transmitted, or to only the Ack symbol in that slot, and not applying any boost to slots not reserved for Ack/Nack transmission or slots in which a Nack has to be sent.

^■ Modifying the NodeB receiver algorithms to account for the extra power boost once the Ack/Nack detector detects that an Ack has been transmitted in a given slot.

2. A method of transmitting acknowledgements on the R99 uplink channel for traffic packets sent on the R99 downlink channel, by sending the Ack/Nack information on an OVSF code channel distinct from that used by the uplink DPCCH or DPDCH.

3. The method of claim 2, where the 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.