1. Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to channel quality index (CQI) reporting and generation in a wireless network, such as a TD-SCDMA network.
2. Background
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 Universal 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). For example, China is pursuing TD-SCDMA as the underlying air interface in the UTRAN architecture with its existing GSM infrastructure as the core network. 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 is a collection of two mobile telephony protocols, High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA), which extends and improves the performance of existing wideband protocols.
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.
Offered is a method of wireless communication. The method includes computing a spectral efficiency metric of each allocated resource of a data channel based at least in part on an amplitude and energy of received symbols of the data channel. The method also includes reporting a channel quality metric based at least in part on the spectral efficiency metric.
Offered is an apparatus for wireless communication. The apparatus includes means for computing a spectral efficiency metric of each allocated resource of a data channel based at least in part on an amplitude and energy of received symbols of the data channel. The apparatus also includes means for reporting a channel quality metric based at least in part on the spectral efficiency metric.
Offered is a computer program product configured for operation in a wireless communication network. The computer program product includes a non-transitory computer-readable medium having non-transitory program code recorded thereon. The program code includes program code to compute a spectral efficiency metric of each allocated resource of a data channel based at least in part on an amplitude and energy of received symbols of the data channel. The program code also includes program code to report a channel quality metric based at least in part on the spectral efficiency metric.
Offered is an apparatus configured for operation of a multi-radio user equipment (UE) in a wireless communication network. The apparatus includes a memory and a processor(s) coupled to the memory. The processor(s) is configured to compute a spectral efficiency metric of each allocated resource of a data channel based at least in part on an amplitude and energy of received symbols of the data channel. The processor(s) is also configured to report a channel quality metric based at least in part on the spectral efficiency metric.
This has outlined, rather broadly, the features and technical advantages of the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages of the disclosure will be described below. It should be appreciated by those skilled in the art that this disclosure may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the teachings of the disclosure as set forth in the appended claims. The novel features, which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages, will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.
The features, nature, and advantages of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout.
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 the 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.
Turning now to
The geographic region covered by the RNS 107 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 transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), or some other suitable terminology. For clarity, two node Bs 108 are shown; however, the RNS 107 may include any number of wireless node Bs. The node Bs 108 provide wireless access points to a core network 104 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. For illustrative purposes, three UEs 110 are shown in communication with the node Bs 108. The downlink (DL), also called the forward link, refers to the communication link from a node B to a UE, and the uplink (UL), also called the reverse link, refers to the communication link from a UE to a node B.
The core network 104, as shown, includes 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.
In this example, the core network 104 supports circuit-switched services with a mobile switching center (MSC) 112 and a gateway MSC (GMSC) 114. One or more RNCs, such as the RNC 106, may be connected to the MSC 112. The MSC 112 is an apparatus that controls call setup, call routing, and UE mobility functions. The MSC 112 also includes a visitor location register (VLR) (not shown) that contains subscriber-related information for the duration that a UE is in the coverage area of the MSC 112. The GMSC 114 provides a gateway through the MSC 112 for the UE to access a circuit-switched network 116. The GMSC 114 includes a home location register (HLR) (not shown) 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 114 queries the HLR to determine the UE's location and forwards the call to the particular MSC serving that location.
The core network 104 also supports packet-data services with a serving GPRS support node (SGSN) 118 and a gateway GPRS support node (GGSN) 120. GPRS, which stands for General Packet Radio Service, is designed to provide packet-data services at speeds higher than those available with standard GSM circuit-switched data services. The GGSN 120 provides a connection for the RAN 102 to a packet-based network 122. The packet-based network 122 may be the Internet, a private data network, or some other suitable packet-based network. The primary function of the GGSN 120 is to provide the UEs 110 with packet-based network connectivity. Data packets are transferred between the GGSN 120 and the UEs 110 through the SGSN 118, which performs primarily the same functions in the packet-based domain as the MSC 112 performs in the circuit-switched domain.
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 over a much wider bandwidth through multiplication by a sequence of pseudorandom bits called chips. The TD-SCDMA standard is based on such direct sequence spread spectrum technology and additionally calls for a time division duplexing (TDD), rather than a frequency division duplexing (FDD) as used in many FDD mode UMTS/W-CDMA systems. TDD uses the same carrier frequency for both the uplink (UL) and downlink (DL) between a node B 108 and a UE 110, but divides uplink and downlink transmissions into different time slots in the carrier.
At the UE 350, a receiver 354 receives the downlink transmission through an antenna 352 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 354 is provided to a receive frame processor 360, which parses each frame, and provides the midamble 214 (
In the uplink, data from a data source 378 and control signals from the controller/processor 390 are provided to a transmit processor 380. The data source 378 may represent applications running in the UE 350 and various user interfaces (e.g., keyboard). Similar to the functionality described in connection with the downlink transmission by the node B 310, the transmit processor 380 provides 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 394 from a reference signal transmitted by the node B 310 or from feedback contained in the midamble transmitted by the node B 310, may be used to select the appropriate coding, modulation, spreading, and/or scrambling schemes. The symbols produced by the transmit processor 380 will be provided to a transmit frame processor 382 to create a frame structure. The transmit frame processor 382 creates this frame structure by multiplexing the symbols with a midamble 214 (
The uplink transmission is processed at the node B 310 in a manner similar to that described in connection with the receiver function at the UE 350. A receiver 335 receives the uplink transmission through the antenna 334 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 335 is provided to a receive frame processor 336, which parses each frame, and provides the midamble 214 (
The controller/processors 340 and 390 may be used to direct the operation at the node B 310 and the UE 350, respectively. For example, the controller/processors 340 and 390 may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. The computer readable media of memories 342 and 392 may store data and software for the node B 310 and the UE 350, respectively. For example, the memory 392 of the UE 350 may store a CQI generation module 391 which, when executed by the controller/processor 390, configures the UE 350 for determining an expected synchronization channel code word based on the operating frequency and base station identification code of a base station. A scheduler/processor 346 at the node B 310 may be used to allocate resources to the UEs and schedule downlink and/or uplink transmissions for the UEs.
CQI Reporting and Generation
A user equipment (UE) reports a channel quality index (CQI) of a downlink (DL) HS-PDSCH (High Speed-Physical Downlink Shared Channel) to a base station to inform the base station of the quality of downlink communications between the base station and the UE. A CQI report may include a recommended modulation format (RMF), and a recommended transport block (TB) size (RTBS). The CQI report may be carried on the HS-SICH (High-Speed Shared Information Channel).
Proposed is a method for a UE to report a channel quality metric (such as a CQI) to a base station based on a calculation of the spectral efficiency of the downlink communications. The teachings below may be applied to a single antenna or to multiple antennae. The UE may compute an effective signal to interference ratio (SIR)/spectral efficiency (SE) metric and use the SE metric to report channel quality. The SE metric may be calculated over one or more resources allocated to the UE. Examples of such a resource may be a code, frequency, and/or time. For example, as described below the UE may calculate the SE metric over all data carrying channels in a particular subframe. As also described below, the UE may filter the SE metric over subframes to arrive at an average value. The UE may then use the SE metric (or averaged SE metric, etc.) to arrive at one or more channel quality metrics, such a recommended modulation format and RTBS, to report to a base station, such as in a CQI report.
A UE may calculate the SE metric in a number of ways. Calculation of the SE metric may be based on a present modulation scheme. As an example, if a present modulation scheme is QPSK (Quadrature Phase Shift Keying) or QAM16 (quadrature amplitude modulation) the SE metric may be calculated as follows. The amplitude (A) and energy (E) of a signal may be determined. The SE metric value may be calculated as A2/E. This SE metric may be calculated for each subframe and/or for each data carrying code channel. The SE metric may then be used to calculate a signal-to-noise ratio (SNR). Alternatively, a look-up-table may be available to the UE which lists SE metrics and corresponding SNR values based on a present modulation scheme The SE metric may also be used to determine a value for a capacity of each code channel allocated to the UE. The capacity may be a measurement of the maximum code rate supported by a particular allocated code channel. The capacity may also be calculated by the UE or pulled from a look-up-table, and may also be based on modulation scheme.
Based on the above calculations/lookups, the UE may average all the individual capacities of each code channel to arrive at a single value of a spectral efficiency metric, called SE effective (SEeff), that may be used to estimate the quality of the transmission in the subframe. To calculate SEeff the UE may average the capacity over all the allocated code channels in a subframe by adding up the capacity of each code channel n for all allocated code channels in a subframe 1 through N, then average that number by dividing by N as shown in the equation below:
As illustrated, one way to calculate the spectral efficiency metric is with the capacity (CAP) function. Other equivalent functions may also be used.
For a different modulation scheme, such as QAM64 modulation, the UE may calculate the SE metric differently. The UE may determine the amplitude (A) and energy (E) values over each allocated code channel. The UE may then average the A and E values over the allocated code channels. Using those average values, the UE may then determine the value of the SE metric Aavg2/Eavg. The UE may then calculate the capacity of the code channel or determine the capacity from a look-up-table. This capacity value may then be used as the effective SE metric, SEeff. These calculations may be performed for each subframe and/or for each data carrying code channel. The calculated SE values may be averaged over multiple subframes. The spectral efficiency value may also be filtered, for example using a single value tap infinite impulse response (IIR) filter. The following equation may be used:
SEavg[n+1]=(1−α)SEavg[n]+αSEeff
where α is an adjustment value to be determined based on field conditions and n represents how many calculations have been performed since receipt of a reset command. The filter may be reset after gaps in high speed transmission. When a reset command is received, at the next SE update, the average SE for the measurement may be set to the effective SE as shown below:
SEavg[1]=SEeff
In one aspect an outer loop may be used to adjust the SEavg based on an adjustment factor as determined by long term statistics. For example, if the UE is over-reporting or under-reporting the CQI metric (and thus misrepresenting the throughput loss) by some shift factor, the SE metric may be adjusted to correct the reporting. This adjusted value may be referred to as SEadj. Techniques for structuring the outer loop and adjusting the SE metric are discussed in co-pending U.S. patent application Ser. No. 14/027,898, in the names of Kang, et al., filed on Sep. 16, 2013 (Attorney Docket Number 124704) and in provisional patent application 61/712,070, filed on Oct. 10, 2012, in the names of Kang, et al., the disclosures of which are expressly incorporated by reference in their entireties. The SE may also be adjusted by converting SEavg into a SIR value, adjusting the SIR value, and then converting back to an SE value.
When an SE metric is determined (be it an average SE metric, effective SE metric, or otherwise) a value for the channel metric may be determined for reporting. For a CQI value, the SE metric may be used to determine a recommended modulation format and RTBS.
The choice of recommended modulation format may be based at least in part on the SE metric and the rate a UE can support. The supported rate may be indicated by a UE category, which may indicate supported modulation formats. Certain SE thresholds (Th) may be established where, if a SE metric falls within those thresholds, a certain modulation format is selected as the recommended modulation format. For example, for UE categories above 15, the recommended modulation format may be chosen using the following equations:
0≦SE≦Th1→select QPSK
Th1<SE≦Th2→select QAM16
Th2<SE→select QAM64
For UE categories 15 or below, the recommended modulation format may be chosen using the following equations:
0≦SE≦Th1→select QPSK
else→select QAM16
The recommended transport block size (RTBS) may also be selected based at least in part on the SE metric. Different values of the SE metric, such as SEavg, may be mapped to different code rate values, for example using a look up table that indicates what code rates are desired for which SE values. Different desired code rates may be based on the recommended modulation format. The RTBS may then be determined based on the code rate and the resource allocation of the most recently decoded High Speed Shared Control Channel (HS-SCCH) and High Speed-Physical Downlink Shared Channel (HS-PDSCH) pair. The number of resources allocated to the UE may be multiplied by the code rate to arrive at a desired RTBS.
A check may be made to ensure that the RTBS does not exceed the capacity of the network, i.e., to make sure that the selected RTBS<1.0 after the addition of a CRC (cyclic redundancy check). The RTBS should satisfy the following check:
where 24 is the size of the CRC, 4 is the number of tail bits for each code segment, CEIL(TBSize/5114) is the number of code segments, and PhChBits is the number of bits allocated to the HS-PDSCH transmission.
The apparatus includes a processing system 514 coupled to a transceiver 530. The transceiver 530 is coupled to one or more antennas 520. The transceiver 530 enables communicating with various other apparatus over a transmission medium. The processing system 514 includes a processor 522 coupled to a computer-readable medium 526. The processor 522 is responsible for general processing, including the execution of software stored on the computer-readable medium 526. The software, when executed by the processor 522, causes the processing system 514 to perform the various functions described for any particular apparatus. The computer-readable medium 526 may also be used for storing data that is manipulated by the processor 522 when executing software.
The processing system 514 includes a computing module 502 for computing a spectral efficiency metric. The processing system 514 includes a reporting module 504 for reporting a channel quality metric. The modules may be software modules running in the processor 522, resident/stored in the computer-readable medium 526, one or more hardware modules coupled to the processor 522, or some combination thereof. The processing system 514 may be a component of the UE 350 and may include the memory 392, and/or the controller/processor 390.
In one configuration, an apparatus such as a UE is configured for wireless communication including means for computing. In one aspect, the above means may be the controller/processor 390, the memory 392, CQI generation module 391, computing module 502, and/or the processing system 514 configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a module or any apparatus configured to perform the functions recited by the aforementioned means.
In one configuration, an apparatus such as a UE is configured for wireless communication including means for reporting. In one aspect, the above means may be the controller/processor 390, the memory 392, CQI generation module 391, reporting module 504, antennae 352, transmitter 356, and/or the processing system 514 configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a module or any apparatus configured to perform the functions recited by the aforementioned means.
Several aspects of a telecommunications system has been presented with reference to TD-SCDMA systems. 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. By way of example, various aspects may be extended to other UMTS systems such as W-CDMA, 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.
Several processors have been described in connection with various apparatuses and methods. These processors may be implemented using electronic hardware, computer software, or any combination thereof. Whether such processors are implemented as hardware or software will depend upon the particular application and overall design constraints imposed on the system. By way of example, a processor, any portion of a processor, or any combination of processors presented in this disclosure may be implemented with a microprocessor, microcontroller, digital signal processor (DSP), a field-programmable gate array (FPGA), a programmable logic device (PLD), a state machine, gated logic, discrete hardware circuits, and other suitable processing components configured to perform the various functions described throughout this disclosure. The functionality of a processor, any portion of a processor, or any combination of processors presented in this disclosure may be implemented with software being executed by a microprocessor, microcontroller, DSP, or other suitable platform.
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 non-transitory computer-readable medium. A computer-readable medium may include, by way of example, memory such as a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., compact disc (CD), digital versatile disc (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, or a removable disk. Although memory is shown separate from the processors in the various aspects presented throughout this disclosure, the memory may be internal to the processors (e.g., cache or register).
Computer-readable media 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.
It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Based upon design 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.
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.”
This application claims the benefit under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 61/711,658 entitled “CQI REPORTING AND GENERATION IN TD-SCDMA,” filed on Oct. 9, 2012 in the names of Khandekar, et al., the disclosure of which is expressly incorporated by reference herein in its entirety.
Number | Date | Country | |
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61711658 | Oct 2012 | US |