HK1218471B - Method, apparatus and medium for scrambling sequence initialization for coordinaed multi-point transmissions - Google Patents

Description

Method, device and medium for initializing scrambling sequence for coordinated multi-point transmission

This application is a divisional application of the Chinese patent application with application number 201080043601.0 (PCT/US2010/050987), application date September 30, 2010, and invention name “Scrambling sequence initialization for coordinated multi-point transmission”.

This application claims priority to U.S. Provisional Patent Application No. 61/247,114, filed September 30, 2009, entitled “PDSCH Scrambling Sequence Initialization for LTE-A,” which is hereby incorporated by reference in its entirety.

Technical Field

The present invention relates generally to the field of wireless communications, and more particularly to initialization of scrambling sequences used in physical channels in wireless communication systems.

Background Art

This section is intended to provide background or context for the disclosed embodiments. The description herein may include concepts that could be implemented, but not necessarily those that have been previously conceived or implemented. Therefore, unless otherwise indicated herein, the material described in this section is not prior art with respect to the description and claims of this application and is not admitted to be prior art by virtue of inclusion in this section.

Wireless communication systems are widely deployed to provide various communication services, such as voice and data. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP long term evolution (LTE) systems, and orthogonal frequency division multiple access (OFDMA) systems.

Orthogonal frequency division multiplexing (OFDM) communication systems effectively divide the entire system bandwidth into multiple subcarriers, which may also be referred to as frequency subchannels, tones, or frequency bins. For an OFDM system, the data to be transmitted (i.e., information bits) is first encoded using a specific coding scheme to produce coded bits, and the coded bits are further grouped into multi-bit symbols, which are then mapped to modulation symbols. Each modulation symbol corresponds to a point in a signal constellation defined by the specific modulation scheme used for data transmission (e.g., M-PSK or M-QAM). A modulation symbol may be transmitted on each frequency subcarrier in each time interval that may be related to the bandwidth of each frequency subcarrier. Therefore, OFDM can be used to prevent inter-symbol interference (ISI) caused by frequency selective fading, which is characterized by varying amounts of attenuation across the system bandwidth.

Typically, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals, which can communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from the base station to the terminal, while the reverse link (or uplink) refers to the communication link from the terminal to the base station. This communication link can be established via a single-input single-output, multiple-input single-output, or multiple-input multiple-output (MIMO) system.

MIMO systems use multiple ( _NT ) transmit antennas and multiple ( _NR ) receive antennas for data transmission. The MIMO channel consisting of _NT transmit antennas and _NR receive antennas can be decomposed into _NS independent channels, which are also called spatial channels. Typically, each of the _NS independent channels corresponds to a dimension. If the additional dimensions created by multiple transmit and receive antennas are utilized, the MIMO system can provide higher performance (e.g., higher throughput and/or greater reliability). MIMO systems also support time division duplex (TDD) and frequency division duplex (FDD) systems. In a TDD system, forward link and reverse link transmissions are on the same frequency range, so that the reciprocity principle allows the forward link channel to be estimated based on the reverse link channel. This enables the access point to extract transmit beamforming gain on the forward link when multiple antennas are available at the access point.

Coordinated multi-point (CoMP) communication provides the possibility that two or more cells can simultaneously serve the same user equipment (UE) to increase the signal-to-noise ratio at the UE. Using CoMP, two or more cells can transmit PDSCH resources to the same UE at substantially the same time, while one cell (the serving cell) manages control signaling on the Physical Downlink Control Channel (PDCCH).

Summary of the Invention

The disclosed embodiments relate to systems, methods, apparatus, and computer program products for generating a shared initialization code to generate a common scrambling sequence for a PDSCH scrambling code in a coordinated multi-point (CoMP) transmission network in an advanced wireless communication system.

In one embodiment, a method includes: generating a shared initialization code in a serving cell of a coordinated multi-point (CoMP) transmission network, wherein the shared initialization code includes a virtual serving cell identifier; initializing a scrambling sequence generator using the shared initialization code; generating a scrambling sequence from the shared initialization code; and generating scrambled data using the scrambling sequence.

In one embodiment, the method includes sending the shared initialization code to the other cell of the CoMP transmission network via a system controller coupled to the serving cell and the other cell of the CoMP transmission network.

In another embodiment, the method includes sending the shared initialization code from the serving cell to a user equipment (UE) on a physical downlink control channel (PDCCH); and sending the scrambled data to the UE on a first physical downlink shared data channel (PSDCH).

In one embodiment, the initialization code includes a user equipment (UE) identifier, a codeword index, and a transmission slot index, wherein, in one embodiment, the UE identifier includes a virtual UE identifier, the codeword index includes one of a serving cell codeword index and a virtual codeword index, and the transmission slot index includes one of a serving cell transmission slot index and a virtual transmission slot index. In another embodiment, the initialization code includes the codeword index, the transmission slot index, and the virtual serving cell identifier.

In one embodiment, the CoMP transmission network includes multiple cells. In another embodiment, the CoMP transmission network includes a single cell.

In one embodiment, the method includes: receiving the shared initialization code at another CoMP cell, and using the shared initialization code to initialize a scrambling sequence generator in the other CoMP cell; using the shared initialization code to generate the scrambling sequence; using the scrambling sequence to generate scrambled data; and sending the scrambled data to the UE on a second PDSCH.

In one embodiment, the method includes: receiving the shared initialization code at the UE; initializing a scrambling sequence generator in the UE using the shared initialization code; generating the scrambling sequence using the shared initialization code; receiving scrambled data on at least one of a first PDSCH and a second PDSCH; and descrambling the scrambled data using the scrambling sequence.

In one embodiment, another method includes: generating a shared initialization code in a serving cell of a coordinated multi-point (CoMP) transmission network, wherein the shared initialization code includes a serving cell identifier; sending the initialization code to another cell in the CoMP transmission network via a system controller coupled to the serving cell and the other cell of the CoMP transmission network; and sending the shared initialization code from the serving cell to a user equipment (UE) on a physical downlink control channel (PDCCH).

In one embodiment, the method further includes: initializing a scrambling sequence generator using the shared initialization code; generating a scrambling sequence from the shared initialization code; generating scrambled data using the scrambling sequence; and sending the scrambled data to a user equipment (UE) on a first physical downlink shared channel (PDSCH).

In one embodiment, the method includes: receiving the shared initialization code at another CoMP cell; initializing a scrambling sequence generator in the other CoMP cell using the shared initialization code; generating the scrambling sequence using the shared initialization code; generating scrambled data using the scrambling sequence; and sending the scrambled data to the UE on a second PDSCH.

In one embodiment, the serving cell identifier includes a virtual serving cell identifier, a UE identifier, a codeword index, and a transmission slot index, wherein, in one aspect, the UE identifier includes a virtual UE identifier.

In one embodiment, the codeword index includes one of a serving cell codeword index and a virtual codeword index, and the transmission slot index includes one of a serving cell slot index and a virtual transmission slot index.

In one embodiment, the initialization code includes the serving cell identifier, the codeword index, and the transmission slot index.

In one embodiment, the method includes: receiving the shared initialization code at the UE; initializing a scrambling sequence generator in the UE using the shared initialization code; generating the scrambling sequence using the shared initialization code; receiving scrambled data on at least one of a first PDSCH and a second PDSCH; and descrambling the scrambled data using the scrambling sequence.

In one embodiment, a method includes: receiving, at a user device, a component of a shared initialization code from a CoMP serving cell, wherein the component of the shared initialization code is configured to generate an uplink scrambling sequence for a CoMP transport network; generating the shared initialization code to initialize a scrambling sequence generator for a physical uplink shared channel; sending the shared initialization code on a physical uplink control channel to a cell in the CoMP transport network, wherein the cell in the CoMP transport network is configured to descramble data on the physical uplink shared channel from the UE using the scrambling sequence generated from the shared initialization code; and sending the scrambled data on the physical uplink shared channel to the cell in the CoMP transport network.

In one embodiment, another method includes: receiving, at a user equipment (UE) from a CoMP serving cell, a shared initialization code configured to generate a common scrambling sequence for a coordinated multi-point (CoMP) transmission network; and sending the shared initialization code to another cell in the CoMP transmission network.

In one embodiment, the another cell in the CoMP transmission network is configured to scramble data using a scrambling sequence generated using the shared initialization code, and to send the scrambled data to the UE.

In one embodiment, the method includes receiving scrambled data at the UE from at least one of: receiving scrambled data on a first PDSCH from the CoMP serving cell and receiving scrambled data on a second PDSCH from another cell in the CoMP transmission network.

In one embodiment, the initialization code includes a codeword index, a transmission slot index, and a cell identifier. In one embodiment, the initialization code further includes a UE identifier. In one embodiment, the UE identifier includes a virtual UE identifier.

In one embodiment, the codeword index includes one of a serving cell codeword index and a virtual codeword index, the transmission slot index includes one of a serving cell transmission slot index and a virtual transmission slot index, and the cell identifier includes one of a serving cell identifier and a virtual cell identifier.

In one embodiment, a serving cell in a CoMP transmission network includes a processor and a memory, wherein the memory includes processor-executable instructions that, when executed by the processor, configure the serving cell to: generate a shared initialization code for the CoMP transmission network, wherein the shared initialization code includes a virtual serving cell identifier; initialize a scrambling sequence generator using the shared initialization code; generate a scrambling sequence from the shared initialization code; and generate scrambled data using the scrambling sequence.

In one embodiment, the memory includes additional processor-executable instructions that, when executed by the processor, configure the serving cell to send the shared initialization code to the other cell of the CoMP transmission network via a system controller coupled to the serving cell and the other cell of the CoMP transmission network.

In one embodiment, the memory further comprises processor-executable instructions that, when executed by the processor, configure the serving cell to transmit the shared initialization code from the serving cell to a user equipment (UE) on a physical downlink control channel (PDCCH).

In one embodiment, the memory includes processor-executable instructions that, when executed by the processor, configure the serving cell to send the scrambled data to the UE on a first physical downlink shared data channel (PSDCH).

In one embodiment, the initialization code includes a user equipment (UE) identifier, a codeword index, and a transmission slot index. In one embodiment, the UE identifier includes a virtual UE identifier, the codeword index includes one of a serving cell codeword index and a virtual codeword index, and the transmission slot index includes one of a serving cell transmission slot index and a virtual transmission slot index.

In one embodiment, the initialization code includes a codeword index, a transmission slot index, and a virtual serving cell identifier.

In one embodiment, a serving cell in a CoMP transmission network includes a processor and a memory, the memory including processor-executable instructions that, when executed by the processor, configure the serving cell to: generate a shared initialization code for the CoMP transmission network, wherein the shared initialization code includes a serving cell identifier; send the initialization code to another cell in the CoMP transmission network via a system controller coupled to the serving cell and another cell of the CoMP transmission network; and send the shared initialization code to a user equipment (UE) on a physical downlink control channel (PDCCH). In one embodiment, the serving cell identifier includes a virtual serving cell identifier.

In one embodiment, the memory further includes processor-executable instructions that, when executed by the processor, configure the serving cell to: initialize a scrambling sequence generator using the shared initialization code; generate a scrambling sequence from the shared initialization code; generate scrambled data using the scrambling sequence; and send the scrambled data to a user equipment (UE) on a physical downlink shared channel (PDSCH).

In one embodiment, the initialization code includes a UE identifier, a codeword index, and a transmission slot index. In one embodiment, the UE identifier includes a virtual UE identifier. In one embodiment, the codeword index includes one of a serving cell codeword index and a virtual codeword index, and the transmission slot index includes one of a serving cell slot index and a virtual transmission slot index. In one embodiment, the initialization code includes a serving cell identifier, a codeword index, and a transmission slot index.

In one embodiment, a communications device includes a processor and a memory, the memory including processor-executable instructions that, when executed by the processor, configure the communications device to: receive a shared initialization code from a CoMP serving cell, the shared initialization code configured to generate a common scrambling sequence for a coordinated multi-point (CoMP) transmission network; and transmit the shared initialization code to another cell in the CoMP transmission network. In one embodiment, the other cell in the CoMP transmission network is configured to scramble data using a scrambling sequence generated using the shared initialization code.

In one embodiment, the memory further includes processor-executable instructions that, when executed by the processor, configure the communications device to receive scrambled data from at least one of: receiving scrambled data from the CoMP serving cell on a first PDSCH, and receiving scrambled data from another cell in the CoMP transmission network on a second PDSCH.

In one embodiment, the initialization code includes a codeword index, a transmission slot index, and a cell identifier. In one embodiment, the initialization code further includes a UE identifier. In one embodiment, the codeword index includes one of a serving cell codeword index and a virtual codeword index, the transmission slot index includes one of a serving cell transmission slot index and a virtual transmission slot index, and the cell identifier includes one of a serving cell identifier and a virtual cell identifier. In one embodiment, the UE identifier includes a virtual UE identifier.

These and other features of the various embodiments, as well as the manner in which they are organized and operated, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings in which like reference numerals are used to refer to like parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

A number of provided embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which:

FIG1 shows a wireless communication system;

FIG2 shows a block diagram of a communication system;

FIG3 shows a scrambling sequence generator in one embodiment;

FIG4 illustrates a wireless communication system configured for coordinated multi-point transmission/reception in one embodiment;

FIG5 is a block diagram illustrating a system configured to use a shared initialization code for scrambling in one embodiment;

FIG6 is a flow chart illustrating a method in an evolved node base station (eNodeB) in one embodiment;

FIG7A is a flow chart illustrating a method in a user device in one embodiment;

FIG7B is a flow chart illustrating another method in a user device in one embodiment;

FIG8 shows a system in one embodiment; and

FIG9 illustrates an exemplary apparatus for processing data in a wireless communication system.

DETAILED DESCRIPTION

In the following description, details and illustrations are set forth for purposes of explanation rather than limitation in order to provide a thorough understanding of the various disclosed embodiments. However, it will be apparent to those skilled in the art that these various embodiments may be implemented in other embodiments that depart from these details and illustrations.

As used herein, the terms "component," "module," "system," and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component can be, but is not limited to, a process running on a processor, a processor, an object, an executable file, an execution thread, a program, and/or a computer. As an example, both an application running on a computing device and the computing device can be a component. One or more components can be located in an execution process and/or an execution thread, and a component can be located on one computer and/or distributed between two or more computers. In addition, these components can be executed from various computer-readable media having various data structures stored thereon. These components can communicate via local and/or remote processes, such as by communicating based on signals having one or more data packets (e.g., data from a component that interacts with a local system, another component in a distributed system, and/or interacts with other systems over a network such as the Internet using the signal).

In addition, certain embodiments are described herein in conjunction with user equipment. User equipment may also be referred to as a user terminal and may include some or all of the functions of a system, a subscriber unit, a user station, a mobile station, a mobile wireless terminal, a mobile device, a node, an equipment, a remote station, a remote terminal, a terminal, a wireless communication device, a wireless communication device or a user agent. User equipment may be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a smart phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a laptop, a handheld communication device, a handheld computing device, a satellite radio, a wireless modem card and/or another processing device for communicating via a wireless system. In addition, various schemes are described herein in conjunction with base stations. A base station may be utilized to communicate with one or more wireless terminals, and a base station may also be referred to as an access point, a node, a node B, an evolved node B (eNB) or some other network entity and may include some or all of its functions. The base station communicates with the wireless terminal via an air interface. Communication may be carried out through one or more sectors. A base station can act as a router between the wireless terminal and the rest of the access network, which may include an Internet Protocol (IP) network, by converting received air-interface frames into IP packets. The base station can also coordinate the management of attributes of the air interface and can also be a gateway between the wired network and the wireless network.

Various aspects, embodiments, or features will be presented in terms of systems that may include multiple devices, components, modules, and the like. It will be understood and appreciated that various systems may include additional devices, components, modules, and the like, and/or may not include all of the devices, components, modules, and the like discussed in conjunction with the figures. Combinations of these aspects may also be used.

Additionally, in the subject description, the word "exemplary" is used to mean "serving as an example, instance, or illustration." Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, the use of the word "exemplary" is intended to present concepts in a concrete manner.

Various disclosed embodiments can be incorporated into a communication system. In one example, such a communication system utilizes orthogonal frequency division multiplexing (OFDM), which effectively divides the overall system bandwidth into multiple ( _NF ) subcarriers, which may also be referred to as frequency subchannels, tones, or frequency bins. In an OFDM system, the data to be transmitted (i.e., information bits) is first encoded using a particular coding scheme to generate coded bits, and the coded bits are further grouped into multi-bit symbols, which are then mapped to modulation symbols. Each modulation symbol corresponds to a point in a signal constellation defined by the particular modulation scheme (e.g., M-PSK or M-QAM) used for data transmission. A modulation symbol can be transmitted on each of the _NF frequency subcarriers in each time interval that can be related to the bandwidth of each frequency subcarrier. Consequently, OFDM can be used to prevent intersymbol interference (ISI) caused by frequency selective fading, which is characterized by varying amounts of attenuation across the system bandwidth.

Typically, a wireless multiple access communication system can simultaneously support communication with multiple wireless terminals. Each terminal can communicate with one or more base stations via transmissions on the forward link and the reverse link. The forward link (or downlink) refers to the communication link from the base station to the terminal, and the reverse link (or uplink) refers to the communication link from the terminal to the base station. This communication link can be established via a single-input single-output, multiple-input single-output, or multiple-input multiple-output (MIMO) system.

MIMO systems typically use multiple ( _NT ) transmit antennas and multiple ( _NR ) receive antennas for data transmission. The MIMO channel consisting of _NT transmit antennas and _NR receive antennas can be decomposed into _NS independent channels, also known as spatial channels, where _NS ≤ min{ _NT , _NR }. Each of the _NS independent channels corresponds to a dimension. If the additional dimensions created by multiple transmit and receive antennas are utilized, the MIMO system can provide higher performance (e.g., higher throughput and/or greater reliability). MIMO systems also support time division duplex (TDD) and frequency division duplex (FDD) systems. In a TDD system, forward and reverse link transmissions are on the same frequency range, so that the reciprocity principle allows the forward link channel to be estimated based on the reverse link channel. This enables the base station to extract transmit beamforming gain on the forward link when multiple antennas are available at the base station.

FIG1 illustrates a wireless communication system in which various disclosed embodiments may be implemented. Base station 100 may include multiple antenna groups, each of which may include one or more antennas. For example, if base station 100 includes six antennas, one antenna group may include a first antenna 104 and a second antenna 106, another antenna group may include a third antenna 108 and a fourth antenna 110, and a third group may include a fifth antenna 112 and a sixth antenna 114. It should be noted that although each antenna group is illustrated as including two antennas, more or fewer antennas may be used in each antenna group.

Referring back to FIG. 1 , first user device 116 is shown, for example, in communication with fifth antenna 112 and sixth antenna 114 to facilitate information transmission to first user device 116 via first forward link 120 and information reception from first user device 116 via first reverse link 118. FIG. 1 also shows second user device 122, for example, in communication with third antenna 108 and fourth antenna 110 to facilitate information transmission to second user device 122 via second forward link 126 and information reception from second user device 122 via second reverse link 124. In a frequency division duplex (FDD) system, communication links 118, 120, 124, and 126 shown in FIG. 1 can use different frequencies for communication. For example, first forward link 120 can use a different frequency than that used by first reverse link 118.

In some embodiments, each group of antennas and/or the area in which they are designated to communicate can be referred to as a sector of the base station. For example, the different antenna groups shown in FIG1 can be designed to communicate with user devices in a sector of base station 100. When communicating via forward links 120 and 126, the transmit antennas of base station 100 utilize beamforming to improve the signal-to-noise ratio of the forward links for different user devices 116 and 122. Furthermore, a base station that uses beamforming to transmit to user devices randomly scattered throughout its coverage area causes less interference to user devices in neighboring cells than a base station that transmits omnidirectionally to all of its user devices using a single antenna.

A communication network that may employ some of the various disclosed embodiments may include logical channels, which are categorized as control channels and traffic channels. Logical control channels may include: a broadcast control channel (BCCH), which is a downlink channel used to broadcast system control information; a paging control channel (PCCH), which is a downlink channel that transmits paging information; and a multicast control channel (MCCH), which is a point-to-multipoint downlink channel used to transmit multimedia broadcast and multicast service (MBMS) scheduling and control information for one or more multicast traffic channels (MTCHs). Typically, after a radio resource control (RRC) connection is established, the MCCH is used only by user devices receiving MBMS. A dedicated control channel (DCCH) is another logical control channel, a point-to-point bidirectional channel used to transmit dedicated control information, such as user-specific control information used by user devices with an RRC connection. A common control channel (CCCH) is also a logical control channel that can be used for random access information. Logical traffic channels may include a dedicated traffic channel (DTCH), which is a point-to-point bidirectional channel dedicated to a single user device for transmitting user information. In addition, a multicast traffic channel (MTCH) may be used for point-to-multipoint downlink transmission of traffic data.

The communication network implementing some of the various disclosed embodiments may also include logical transport channels, which are classified into downlink (DL) and uplink (UL). DL transport channels may include: a broadcast channel (BCH), a downlink shared data channel (DL-SDCH), a multicast channel (MCH), and a paging channel (PCH). UL transport channels may include a random access channel (RACH), a request channel (REQCH), an uplink shared data channel (UL-SDCH), and multiple physical channels. Physical channels may also include a set of downlink channels and uplink channels.

In some disclosed embodiments, the downlink physical channels may include at least one of the following: a common pilot channel (CPICH), a synchronization channel (SCH), a common control channel (CCCH), a shared downlink control channel (SDCCH), a multicast control channel (MCCH), a shared uplink assignment channel (SUACH), an acknowledgement channel (ACKCH), a downlink physical shared data channel (DL-PSDCH), an uplink power control channel (UPCCH), a paging indication channel (PICH), a load indication channel (LICH), a physical broadcast channel (PBCH), a physical control format indicator channel (PCFICH), a physical downlink control channel (PDCCH), a physical hybrid ARQ indicator channel (PHICH), a physical downlink shared channel (PDSCH), and a physical multicast channel (PMCH). The uplink physical channels may include at least one of the following: physical random access channel (PRACH), channel quality indicator channel (CQICH), acknowledgement channel (ACKCH), antenna subset indication channel (ASICH), shared request channel (SREQCH), uplink physical shared data channel (UL-PSDCH), broadband pilot channel (BPICH), physical uplink control channel (PUCCH) and physical uplink shared channel (PUSCH).

In addition, the following terms and features are used in describing the various disclosed embodiments:

3G third generation

3GPP Third Generation Partnership Project

ACLR Adjacent Channel Leakage Ratio

ACPR Adjacent Channel Power Ratio

ACS Adjacent Channel Selectivity

ADS Advanced Design System

AMC Adaptive Modulation and Coding

A-MPR Additional Maximum Power Reduction

ARQ Automatic Repeat Request

BCCH Broadcast Control Channel

BTS Base Transceiver Station

CDD Cyclic Delay Diversity

CCDF complementary cumulative distribution function

CDMA Code Division Multiple Access

CFI Control Format Indicator

Co-MIMO

CP Cyclic Prefix

CPICH Common Pilot Channel

CPRI Common Public Radio Interface

CQI Channel Quality Indicator

CRC Cyclic Redundancy Check

DCI Downlink Control Indicator

DFT Discrete Fourier Transform

DFT-SOFDM Discrete Fourier Transform Spread Spectrum OFDM

DL Downlink (base station to user transmission)

DL-SCH Downlink Shared Channel

DSP digital signal processing

DT Development Kit

DVSA Digital Vector Signal Analysis

EDA Electronic Design Automation

E-DCH Enhanced Dedicated Channel

E-UTRAN Evolved UMTS Terrestrial Radio Access Network

eMBMS Evolved Multimedia Broadcast Multicast Service

eNB Evolved Node B

EPC Evolved Packet Core

EPRE Energy per resource unit

ETSI European Telecommunications Standards Institute

E-UTRA Evolved UTRA

E-UTRAN Evolved UTRAN

EVM Error Vector Magnitude

FDD Frequency Division Duplex

FFT Fast Fourier Transform

FRC Fixed Reference Channel

FS1 Frame structure type 1

FS2 Frame structure type 2

GSM Global System for Mobile Communications

HARQ Hybrid Automatic Repeat Request

HDL Hardware Description Language

HI HARQ indication

HSDPA High Speed Downlink Packet Access

HSPA High Speed Packet Access

HSUPA High Speed Uplink Packet Access

IFFT inverse FFT

IoT interoperability testing

IP Internet Protocol

LO local oscillator

LTE Long Term Evolution

MAC Media Access Control

MBMS Multimedia Broadcast Multicast Service

MBSFN Multicast/Broadcast over Single Frequency Network

MCH Multicast Channel

MIMO Multiple Input Multiple Output

MISO Multiple Input Single Output

MME Mobility Management Entity

MOP Maximum Output Power

MPR Maximum Power Reduction

MU-MIMO Multi-User MIMO

NAS Non-Access Stratum

OBSAI Open Base Station Architecture Interface

OFDM Orthogonal Frequency Division Multiplexing

OFDMA Orthogonal Frequency Division Multiple Access

PAPR Peak to Average Power Ratio

PAR Peak to Average Ratio

PBCH Physical Broadcast Channel

P-CCPCH Primary Common Control Physical Channel

PCFICH Physical Control Format Indicator Channel

PCH Paging Channel

PDCCH Physical Downlink Control Channel

PDCP Packet Data Convergence Protocol

PDSCH Physical Downlink Shared Channel

PHICH Physical Hybrid ARQ Indicator Channel

PHY Physical Layer

PRACH Physical Random Access Channel

PMCH Physical Multicast Channel

PMI precoding matrix indicator

P-SCH Primary Synchronization Signal

PUCCH Physical Uplink Control Channel

PUSCH Physical Uplink Shared Channel

FIG2 illustrates a block diagram of an exemplary communication system in which various embodiments may be implemented. The MIMO communication system 200 shown in FIG2 includes a transmitter system 210 (e.g., a base station or access point) and a receiver system 250 (e.g., an access terminal or user device) within the MIMO communication system 200. Those skilled in the art will appreciate that, even though the base station is referred to as the transmitter system 210 and the user device is referred to as the receiver system 250, embodiments of these systems are capable of bidirectional communication. In this regard, the terms "transmitter system 210" and "receiver system 250" should not be used to imply unidirectional communication from either system. It should also be noted that the transmitter system 210 and receiver system 250 of FIG2 are each capable of communicating with multiple other receiver systems and transmitter systems, not explicitly shown in FIG2. At the transmitter system 210, traffic data for multiple data streams is provided from a data source 212 to a transmitter (TX) data processor 214. Each data stream may be transmitted via its own transmitter system. TX data processor 214 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data.

The coded data for each data stream can be multiplexed with pilot data using, for example, OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and can be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (symbol mapped) based on a particular modulation scheme (e.g., BPSK, QPSK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream can be determined by instructions executed by the processor 230 of the transmitter system 210.

2 , the modulation symbols for all data streams are provided to a TX MIMO processor 220, which may further process the modulation symbols (e.g., for OFDM). TX MIMO processor 220 then provides _NT modulation symbol streams to _NT transmitter system transceivers (TMTRs) 222a through 222t. In one embodiment, TX MIMO processor 220 may further apply beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

Each transmitter system transceiver 222a through 222t receives and processes a respective symbol stream to provide one or more analog signals, and further conditions the analog signals to provide a modulated signal suitable for transmission via the MIMO channel. In some embodiments, the conditioning may include, but is not limited to, operations such as amplification, filtering, and frequency upconversion. The modulated signals generated by the transmitter system transceivers 222a through 222t are then transmitted from the transmitter system antennas 224a through 224t shown in FIG.

At receiver system 250, the transmitted modulated signals are received by receiver system antennas 252a through 252r. A received signal from each receiver system antenna 252a through 252r is provided to a respective receiver system transceiver (RCVR) 254a through 254r. Each receiver system transceiver 254a through 254r conditions the respective received signal, digitizes the conditioned signal to provide samples, and may further process the samples to provide a corresponding "received" symbol stream. In some embodiments, conditioning may include, but is not limited to, operations such as filtering, amplification, and downconversion.

The RX data processor 260 then receives and processes the symbol streams from the receiver system transceivers 254a through 254r based on a particular receiver processing technique to provide a plurality of "detected" symbol streams. In one example, each detected symbol stream includes symbols that can be estimates of the symbols transmitted for the corresponding data stream. The RX data processor 260 then at least partially demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the corresponding data stream. The processing by the RX data processor 260 can be complementary to that performed by the TX MIMO processor 220 and the TX data processor 214 at the transmitter system 210. The RX data processor 260 can also provide the processed symbol streams to a data sink 264.

In some embodiments, a channel response estimate is generated by RX data processor 260 and may be used at receiver system 250 to perform space/time processing, adjust power levels, change modulation rates or schemes, and/or other appropriate operations. Additionally, RX data processor 260 may further estimate channel characteristics such as the signal-to-noise ratio (SNR) and signal-to-interference ratio (SIR) of the detected symbol streams. RX data processor 260 may then provide the estimated channel characteristics to processor 270. In one example, RX data processor 260 and/or processor 270 of receiver system 250 may further derive an estimate of the "operating" SNR for the system. Processor 270 of receiver system 250 may also provide channel state information (CSI), which may include information about the communication link and/or received data stream. This information may include, for example, the operating SNR and other channel information, which may be used by transmitter system 210 (e.g., a base station or eNodeB) to make appropriate decisions, such as user device scheduling, MIMO configuration, modulation and coding selection, and the like. At the receiver system 250, the CSI generated by processor 270 is processed by the TX data processor 238, modulated by the modulator 280, conditioned by the receiver system transceivers 254a through 254r, and transmitted back to the transmitter system 210. Additionally, a data source 236 at the receiver system 250 may provide additional data to be processed by the TX data processor 238.

In some embodiments, the processor 270 at the receiver system 250 may also periodically determine which precoding matrix to use. The processor 270 formulates a reverse link message, which includes a matrix index portion and a rank value portion. The reverse link message may include various information related to the communication link and/or the received data stream. The reverse link message may then be processed by the TX data processor 238 at the receiver system 250, which also receives traffic data for multiple data streams from the data source 236. The processed information is then modulated by the modulator 280, conditioned by one or more receiver system transceivers 254a to 254r, and transmitted back to the transmitter system 210.

In some embodiments of the MIMO communication system 200, the receiver system 250 is capable of receiving and processing spatially multiplexed signals. In these systems, spatial multiplexing is performed at the transmitter system 210 by multiplexing and transmitting different data streams across the transmitter system antennas 224a through 224t. This is in contrast to using a transmit diversity scheme, in which the same data stream is transmitted from multiple transmitter system antennas 224a through 224t. In MIMO communication systems 200 capable of receiving and processing spatially multiplexed signals, a precoding matrix is typically used at the transmitter system 210 to ensure that the signals transmitted from each transmitter system antenna 224a through 224t are sufficiently decorrelated from one another. This decorrelation ensures that the composite signal arriving at any particular receiver system antenna 252a through 252r can be received and the individual data streams can be determined in the presence of signals carrying other data streams from other transmitter system antennas 224a through 224t.

Because the amount of cross-correlation between streams can be affected by the environment, it is advantageous for receiver system 250 to provide feedback to transmitter system 210 regarding the received signal. In these systems, both transmitter system 210 and receiver system 250 include a codebook with multiple precoding matrices. In some cases, each of these precoding matrices can be related to the amount of cross-correlation experienced in the received signal. Because sending the index of a particular matrix is more advantageous than sending the value within the matrix, the feedback control signal sent from receiver system 250 to transmitter system 210 typically includes the index of the particular precoding matrix. In some cases, the feedback control signal also includes a rank index, which indicates to transmitter system 210 how many independent data streams are used in spatial multiplexing.

Other embodiments of MIMO communication system 200 are configured to utilize a transmit diversity scheme instead of the spatial multiplexing scheme described above. In these embodiments, identical data streams are transmitted on transmitter system antennas 224a through 224t. In these embodiments, the data rate transmitted to receiver system 250 is typically lower than in a MIMO communication system 200 employing spatial multiplexing. These embodiments improve the robustness and reliability of the communication channel. In a transmit diversity system, each signal transmitted from transmitter system antennas 224a through 224t is subject to a different interference environment (e.g., fading, reflections, multipath phase shifts). In these embodiments, the different signal characteristics received at receiver system antennas 252a through 252r are useful in determining the appropriate data stream. In these embodiments, the rank indicator is typically set to 1, indicating that transmitter system 210 does not utilize spatial multiplexing.

Other embodiments may utilize a combination of spatial multiplexing and transmit diversity. For example, in a MIMO communication system 200 utilizing four transmitter system antennas 224a through 224t, a first data stream may be transmitted on two of the transmitter system antennas 224a through 224t, and a second data stream may be transmitted on the remaining two of the transmitter system antennas 224a through 224t. In these embodiments, the rank index is set to an integer lower than the full rank of the precoding matrix to indicate to the transmitter system 210 that a combination of spatial multiplexing and transmit diversity is being used.

At the transmitter system 210, the modulated signals from the receiver system 250 are received by the transmitter system antennas 224a through 224t, conditioned by the transmitter system transceivers 222a through 222t, demodulated by the transmitter system demodulator 240, and processed by the RX data processor 242 to extract the reverse link message sent by the receiver system 250. In some embodiments, the processor 230 of the transmitter system 210 then determines which precoding matrix to use for future forward link transmissions and then processes the extracted message. In other embodiments, the processor 230 uses the received signals to adjust beamforming weights for future forward link transmissions.

In other embodiments, the reported CSI is provided to the processor 230 of the transmitter system 210 and used to determine, for example, the data rate and coding and modulation scheme to be used for one or more data streams. The determined coding and modulation scheme can then be provided to one or more transmitter system transceivers 222a through 222t at the transmitter system 210 for quantization and/or use in later transmission to the receiver system 250. Additionally and/or alternatively, the reported CSI can be used by the processor 230 of the transmitter system 210 to generate various controls for the TX data processor 214 and the TX MIMO processor 220. In one embodiment, the CSI and/or other information processed by the RX data processor 242 of the transmitter system 210 can be provided to a data sink 244.

In some embodiments, processor 230 at transmitter system 210 and processor 270 at receiver system 250 may direct the operations of their respective systems. Additionally, memory 232 at transmitter system 210 and memory 272 at receiver system 250 may provide storage for program codes and data used by transmitter system processor 230 and receiver system processor 270, respectively. Furthermore, at receiver system 250, a variety of processing techniques may be used to process the _NR received signals to detect the _NT transmitted symbol streams. These receiver processing techniques may include spatial receiver processing techniques and space-time receiver processing techniques, which may include equalization techniques, "successive zero forcing/equalization and interference cancellation" receiver processing techniques, and/or "successive interference cancellation" or "successive cancellation" receiver processing techniques.

In LTE Rel-8, the physical downlink layer primarily converts data into reliable signals for transmission over the radio interface between the eNodeB and the user equipment (UE). Channel coding is first used to protect each data block from transmission errors. In LTE Rel-8, a codeword is an independently coded data block corresponding to a single transport block (TB) passed from the media access control (MAC) layer to the physical layer and protected by a CRC.

Depending on the rank of the transmission, there can be one or two codewords, where the rank is equal to the number of spatial layers. Spatial layers is the term used in LTE for the different streams resulting from spatial multiplexing and can be described as the mapping of symbols onto transmit antenna ports. For ranks greater than 1, two codewords can be sent. The number of codewords is always less than or equal to the number of layers, which in turn is always less than or equal to the number of antenna ports.

Figure 3 illustrates the formation of a downlink LTE signal after channel coding. Codewords 301 are scrambled in the scrambling stage 302. Following scrambling 302, data bits from each channel are mapped to complex-valued modulation symbols in the modulation mapper 304 and subsequently to layers in the layer mapper 306. Each layer 307 is precoded in the precoder 308, where each layer is identified by a precoding vector whose size equals the number of transmit antenna ports. The data in each layer is then mapped to resource elements (REs) in the RE mapper 310. A resource element is the smallest unit of resource in LTE and consists of one OFDM subcarrier for the duration of one OFDM symbol. Finally, the REs are converted into complex-valued OFDM signals using the IFFT in the OFDM signal generator 312 and output to antenna ports 313.

Scrambling is applied to all downlink physical channels and serves as a shield against interference. The scrambling sequence in all cases uses a 31-order Gold code, which provides 2 ³¹ sequences that are not cyclically shifted from each other. Gold codes also have the attractive feature of being generated with very low implementation complexity because they can be derived from the modulo-2 addition of two maximum-length sequences (called M-sequences), which can be generated using a simple shift register. Figure 4 shows an exemplary shift register implementation of the LTE Rel-8 scrambling sequence generator.

As shown in FIG4 , the scrambling sequence generator 400 includes two 31-bit maximum length linear feedback shift registers 401 and 402 having characteristic polynomials (x ³¹ +x ²⁸ +1) and (x ³¹ +x ³⁰ +x ²⁹ +x ²⁸ +1), respectively. The outputs of the two registers 401 and 402 are added modulo 2 in an adder 403.

For LTE Rel-8 PDSCH transmission, based on the cell identity (9 bits), transmission slot index (5 bits), codeword index (1 bit) and UE identifier (16 bits), a scrambling sequence generator (e.g., generator 400) is initialized with a coded bit block c _init at the beginning of each subframe according to the following formula:

Where n _RNTI corresponds to the radio network temporary identifier (RNTI) associated with the PDSCH transmission, q is the codeword index (0 or 1), n _s is the slot index (0 to 19), and N _ID ^cell is the ID of a given cell. This is shown in Figure 4. In addition, after each initialization, a fast forward of 1600 positions is applied to ensure low cross-correlation between sequences used in neighboring cells.

A similar process is performed in case of Physical Uplink Shared Channel (PUSCH) transmission, where the scrambling sequence generator in the UE is initialized. However, in case of uplink, the scrambling initialization code is given by:

where n is _{the RNTI} and is as defined above, and _ns is the transmission slot index of the uplink transmission frame. The structure of the initialization code for the uplink differs from that for the downlink in that there is no codeword index q associated with the uplink initialization code.

While this approach randomizes interference between cells and between UEs, it also results in additional operations and overhead in the management of coordinated multi-point transmission. Downlink coordinated multi-point (DL-CoMP) transmission makes it possible for two or more cells to serve the same UE simultaneously. That is, two or more cells can send PDSCH to the same UE almost simultaneously. In some schemes, control signaling (PDSCH) is sent from only one cell (denoted as the serving cell). It is therefore desirable for all cells involved in DL-CoMP to have the same PDSCH scrambling sequence. This is particularly relevant for dynamic switching between single-point transmission and multi-point (CoMP) transmission - UE transparent single-point/multi-point transmission. For transparent operation, the scrambling of the reference signals (RS) and data from different cells participating in the joint transmission to a given UE should be the same. However, it will be appreciated that the initialization code given in equation (1) is cell-specific, where its current form results in different PDSCH scrambling sequences for different cells. Note also that the UE specific ID (n _RNTI ) is implicitly included in the aforementioned PDSCH scrambling sequence initialization.

Figure 5 illustrates a cluster of cells (501, 503, 505) in a wireless network with respective base stations 502, 504, and 506. For example, to maintain communication using base station 502 in sector 507 and base station 504 in sector 508 in DL-CoMP mode, UE 510 can generate two different scrambling sequences based on two different initialization codes. One scrambling sequence is generated from an initialization code based on the cell ID of base station 502, the RNTI of UE 510, the codeword index for base station 502, and the transmission slot index of base station 502. Another scrambling sequence is generated from an initialization code based on the cell ID of base station 504, the RNTI of UE 510, the codeword index for base station 504, and the transmission slot index of base station 504. Additionally, if UE 510 is mobile and moves into range of base station 506 in cell 505, UE 510 may need to generate a third scrambling sequence based on parameters associated with base station 506 during the handover process. All of this complexity creates a considerable amount of control channel signaling overhead.

According to the solution of the present disclosure, these additional complexities regarding DL-CoMP can be avoided. In order to solve the problem of cell-specific scrambling, in one embodiment, a method is provided so that all cells involved in the DL-CoMP operation use a pre-specified cell ID of the serving cell. That is,

Where is the ID of the designated serving cell, regardless of whether this given cell is the actual serving cell. Another possibility is to assign a virtual ID associated with a group of cells such as cells 501, 503, and 505. This virtual ID can be semi-statically configured and indicated to the UE. In this case, the initialization code is given by:

Note that the group ID or virtual ID may or may not be associated with the cell ID serving the UE.

In order to reduce the complexity involved in the cells involved in DL-CoMP operation, it is desirable to omit the UE ID from the initialization code used for scrambling operation. In this case, the initialization code is simplified to:

Where N _ID is the serving cell ID or a virtual ID representing the group. In this case, the bits in the scrambling sequence generator can be padded with zeros to maintain compatibility with LTE Rel-8 requirements. Alternatively, a virtual UE ID n _virtual can be used, similar to the virtual cell ID described above, so that the initialization code is defined as:

For the cells involved in CoMP operation, it is desirable that these cells be aligned at least on subframe boundaries. However, it is possible that different cells may have different subframe indices. For example, cell 501 may be aligned on subframes 0, 1, 2, 3, etc., while cell 503 may be aligned on subframes 1, 2, 3, 4, etc. That is, the two cells are aligned on subframe boundaries but not necessarily on subframe indices (i.e., not fully synchronized, or not radio frame aligned). In this case, the _ns value used in the above scrambling should be the same for all involved cells and can be based on the subframe index of the serving cell or based on a virtual subframe/time slot index, where all involved cells exchange and share a common value.

Similarly, for example, the transmission slot index can be replaced by the slot index of the serving cell or a virtual slot index assigned to the group. The same scheme can be applied to the codeword index to specify the codeword index of the serving cell or a virtual codeword. It should be noted that these changes to the parameters of the scrambling sequence initialization code will not affect the normal operation of other UEs in the group. It should also be noted that the use of virtual parameters in the initialization code will not affect the randomness of the CoMP scrambling sequence relative to other UEs in the CoMP cell.

As described above, the initialization code for the physical uplink shared channel (PUSCH) in the UE has the same structure as the initialization code for the PDCCH, except for the lack of a codeword index (which is not relevant for the uplink). Therefore, all the configurations described for the downlink scrambling initialization code, except for the codeword option, can also be applied to the uplink. That is, according to this disclosure, the uplink scrambling initialization code can use a serving cell identifier or a virtual serving cell identifier, a UE identifier or a virtual UE identifier, and a UE transmission slot index or a virtual UE transmission slot index. Similarly, the uplink scrambling initialization code can omit the UE identifier.

A similar scheme can be used to generate a scrambling sequence to scramble the UE Reference Signal (UE-RS) for all cells involved in the CoMP transmission.

A scheme for initializing the UE-RS sequence is given by:

In order to generate the same UE-RS random sequence for all cells involved, the same design principle as above is also applicable. Specifically, c _init can be defined as follows:

Wherein, N _ID is a designated serving cell ID or a virtual cell ID.

Communication of these common initialization parameter values (virtual or otherwise) between CoMP cells may be accomplished via a backhaul controller, such as system controller 520 in FIG. 5 , described in detail below.

For the uplink, the UE may receive relevant parameters (i.e., serving cell identifier and UE identifier) and may then send uplink initialization code parameters (serving cell identifier, UE identifier, and UE transmission slot index) to other cells participating in the UL-CoMP (i.e., point-to-multipoint) transmission network via the Physical Uplink Control Channel (PUCCH) to enable scrambled transmission on the Physical Uplink Shared Channel (PUSCH).

FIG8 illustrates a system 800 according to an exemplary embodiment. In FIG8 , base station 810 is designated as a CoMP serving cell, base station 820 is a CoMP cell in a CoMP transmission network, and user equipment (UE) 830 is a UE configured for DL-CoMP. System 800 utilizes an initialization code generator 801 and a scrambling sequence generator 802 in each base station and UE involved in DL-CoMP transmission. Base station 810 communicates with UE 830 via downlink 803, which supports a physical downlink control channel (PDCCH) 804 and a physical downlink shared channel (PDCCH) 805. Base station 820 communicates with UE 830 via downlink 806, which supports a PDCCH 807 and a PDSCH 809. In turn, UE 830 communicates with base station 820 via uplink 810, which supports a physical uplink control channel (PUCCH) 811 and a physical uplink shared channel (PUSCH) 812. Communications between base station 810 and base station 820 are managed by a system controller 840. Although FIG8 shows only two base stations and one UE, it will be appreciated that the embodiments provided are not limited in this regard and may include more than two base stations and more than one UE.

Generally, system 800 generates a shared initialization code for use in scrambling sequence generation in each base station and UE involved in a CoMP transmission network (collectively referred to as a CoMP participant), and each CoMP participant includes: a scrambling sequence generator 802, which can be implemented in hardware, software, firmware, or some combination thereof, as is known in the art; and an initialization code generator 801, which can be implemented in hardware, software, firmware, or some combination thereof, as is known in the art.

In general, system 800 generates the same shared scrambling initialization code for PDSCH between a CoMP base station and a UE so that the same (i.e., common) sequence is generated by all cells involved in downlink (DL) coordinated multipoint transmission/reception (CoMP) operation to optimize switching operations between single-point and multipoint CoMP transmissions. Similarly, system 800 generates the same shared scrambling initialization code for PUSCH transmission between a UE configured for CoMP operation and a CoMP base station so that the scrambling sequence used to scramble data transmissions on the PUSCH is the same as the scrambling sequence used by the CoMP base station to descramble data transmissions on the PUSCH.

In one approach, all cells involved in DL-CoMP can use the same serving cell identifier (ID), regardless of whether a given cell is the serving cell. This cell ID can be communicated between cells as a parameter, with each cell subsequently using the same cell ID during initialization. In another approach, a virtual ID is generated and used by each cell involved in DL-CoMP operations or communications. Similarly, requiring all cells other than the serving cell to use the same cell ID can facilitate switching between single-point and multi-point CoMP transmissions.

In system 800 of FIG8 , base station 810 (CoMP serving cell) is configured to generate a shared initialization code using initialization code generator 801 based on a real or virtual cell identifier, a real or virtual codeword index, a real or virtual transmission slot index, and optionally, a real or virtual identifier of UE 830. Base station 810 is configured to send the shared initialization code to UE 830 on downlink 803 using PDCCH 804.

The base station 810 is also configured to send a shared initialization code parameter to the base station 820 (CoMP cell) via the controller 840. The base station 820 is configured to generate a shared initialization code locally, initialize the local scrambling sequence generator 802, and scramble data to be sent on the downlink 806 to the UE 830 via the PDCCH 807.

UE 830 is configured to receive a shared initialization code or code parameters on PDCCH 804, and locally generate a shared initialization code in generator 801, initialize its local sequence generator 802, and generate a descrambling sequence based on the initialization code. UE 830 is further configured to receive scrambled data from base station 810 on PDSCH 803 and from base station 820 on PDSCH 809, and descramble the scrambled data using the descrambling code.

In other embodiments, base station 810 does not send the initialization code to base station 820. Instead, after receiving the initialization code from base station 810 on PDCCH 804, UE 830 sends the initialization code to base station 820 on uplink 810 via physical uplink control channel 811. After receiving the initialization code from UE 830, base station 820 processes the code as described above, scrambles the data, and sends the data to UE 830.

In another embodiment, UE 830 receives a serving cell identifier or a virtual serving cell identifier and a UE identifier or a virtual UE identifier from base station 810. UE 830 may then use the serving cell identifier (real or virtual), the UE identifier (real or virtual), and the PUSCH transmission slot index (real or virtual) associated with the UE to generate a UL-CoMP initialization code for PUSCH CoMP transmission and send the initialization code or its parameters to base station 820 on PUCCH 811 (and to base station 810 on another PUCCH, not shown). UE 830 may then send scrambled UL-CoMP data to base stations 810 and 820 on corresponding PUSCHs, and base stations 810 and 820 may descramble the scrambled PUSCH data using a descrambling sequence generated from the UL-CoMP scrambling initialization code received from UE 830.

Fig. 6 is a flow chart illustrating a method 600 according to an embodiment provided. For simplicity of explanation, the method is shown and described as a series of operations. However, it will be understood that the method is not limited by the order of operations, because according to one or more embodiments, some operations can be performed in a different order than shown and described herein and/or performed simultaneously with other operations. For example, those skilled in the art will understand and appreciate that the method can be represented as a series of related states or events, such as in a state diagram, alternatively. In addition, according to one or more embodiments disclosed, not all illustrated operations are required to implement the method.

In FIG6 , and with reference to exemplary system 800, the method begins at operation 602, where a shared initialization code is generated in a serving cell 810 of a CoMP transmission network, wherein the shared initialization code includes at least a virtual serving cell ID and a virtual UE identifier. At operation 604, the shared initialization code is transmitted to another cell 820 of the CoMP transmission network. Another cell 820 may be coupled to serving cell 810 via a system controller 840. At operation 606, the shared initialization code is transmitted from serving cell 810 to UE 830 on a physical downlink control channel (PDCCH) 804. At operation 608, a scrambling sequence generator 802 in serving cell 810 is initialized using the initialization code. At operation 610, a scrambling sequence is generated by sequence generator 802 in serving cell 810, and at operation 612, scrambled data is generated using the scrambling sequence. As described above, the initialization code may include: a serving cell ID or a virtual serving cell ID, a UE ID, a virtual UE ID or no UE ID, a codeword index or a virtual codeword index, and a transmission slot index or a virtual transmission slot index.

FIG7A is a flow chart illustrating a method 700 according to one provided embodiment. In FIG7A , and with reference to exemplary system 800, method 700 begins at operation 702, where a UE 830 receives a shared initialization code from a CoMP serving cell 810, wherein the shared initialization code is configured to generate a common scrambling sequence for a coordinated multi-point (CoMP) transmission network. At operation 704, UE 830 transmits the shared initialization code to another cell 820 in the CoMP transmission network, where the other cell in the CoMP transmission network scrambles data using the scrambling sequence generated using the shared initialization code and transmits the scrambled data to the UE. At operation 706, UE 830 receives scrambled data from at least one of: receiving scrambled data on a first PDSCH 805 from the CoMP serving cell 810, and receiving scrambled data on a second PDSCH 809 from another cell 820 in the CoMP transmission network.

FIG7B is a flow chart illustrating a method 750 according to one provided embodiment. In FIG7B , and with reference to exemplary system 800, method 750 begins at operation 752, where UE 830 receives a component of a shared initialization code from CoMP serving cell 810, wherein the component of the shared initialization code is configured to generate an uplink scrambling sequence for the CoMP transmission network. At operation 754, UE 830 generates a shared initialization code to initialize a scrambling sequence generator for a physical uplink shared channel (PUSCH). At operation 756, UE 830 transmits the shared initialization code on a physical uplink control channel (PUCCH) to a cell (e.g., 810 or 820) in the CoMP transmission network, wherein the cell in the CoMP transmission network is configured to descramble data on the PUSCH from the UE using the scrambling sequence generated from the shared initialization code. At operation 758, the UE transmits the scrambled data on the PUSCH to the cell in the CoMP transmission network.

FIG9 illustrates an apparatus 900 in which various disclosed embodiments may be implemented. Specifically, the apparatus 900 shown in FIG9 may include at least a portion of an access point (e.g., base stations 810 and 820 shown in FIG8 ), at least a portion of a user device (e.g., user device 830 shown in FIG8 ), at least a portion of a system controller (e.g., system controller 840 shown in FIG8 ), and/or at least a portion of a transmitter system or a receiver system (e.g., transmitter system 210 and receiver system 250 shown in FIG2 ). The apparatus 900 shown in FIG9 may be located in a wireless network and receive input data, for example, via one or more receivers and/or appropriate receiving and decoding circuitry (e.g., antennas, transceivers, demodulators, etc.). The apparatus 900 shown in FIG9 may also transmit output data, for example, via one or more transmitters and/or appropriate encoding and transmitting circuitry (e.g., antennas, transceivers, modulators, etc.). Additionally or alternatively, the apparatus 900 shown in FIG9 may be located in a wired network.

FIG9 also shows that the apparatus 900 may include a memory 902 that can store instructions for performing one or more operations, such as signal conditioning, analysis, etc. In addition, the apparatus 900 shown in FIG9 may include a processor 904 that can execute instructions stored in the memory 902 and/or instructions received from another device. For example, the instructions may be related to configuring or operating the apparatus 900 or a related communication device. It should be noted that although the memory 902 shown in FIG9 is shown as a single block, it may include two or more separate memories that constitute separate physical and/or logical units. In addition, when the memory is communicatively connected to the processor 904, it may be located entirely or partially outside the apparatus 900 shown in FIG9 . It will also be understood that one or more components or modules such as the initialization code generator 801 and sequence generator 802 shown in FIG8 may be located in a memory such as the memory 902.

It will be appreciated that the memory described in conjunction with the disclosed embodiments may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. By way of example and not limitation, the non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable ROM (EEPROM), or flash memory. The volatile memory may include random access memory (RAM), which may serve as external cache memory. By way of example and not limitation, the RAM may be provided in a variety of ways, such as synchronous RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM).

It should also be noted that the apparatus 900 of Figure 9 can be used in conjunction with a user device or mobile device, and can be, for example, a module such as an SD card, a network card, a wireless network card, a computer (including a laptop, a desktop, a personal digital assistant (PDA), a mobile phone, a smart phone, or any other suitable terminal that can be used to access a network. The user device accesses the network by means of an access component (not shown). In one example, the connection between the user device and the access component can be wireless in nature, wherein the access component can be a base station and the user device is a wireless terminal. For example, the terminal and the base station can communicate by means of any suitable wireless protocol, including but not limited to: time division multiple access (TDMA), code division multiple access (CDMA), frequency division multiple access (FDMA), orthogonal frequency division multiplexing (OFDM), FLASH OFDM, orthogonal frequency division multiple access (OFDMA), or any other suitable protocol.

An access component can be an access node associated with a wired or wireless network. For this purpose, the access component can be, for example, a router, a switch, or the like. The access component can include one or more interfaces, such as a communication module, for communicating with other network nodes. Alternatively, the access component can be a base station (or wireless access point) in a cellular network, where a base station (or wireless access point) is used to provide wireless coverage to multiple users. Such base stations (or wireless access points) can be deployed to provide continuous coverage to one or more cellular phones and/or other wireless terminals.

It will be understood that the embodiments and features described herein can be implemented by hardware, software, firmware, or any combination thereof. The various embodiments described herein are described in the context of a method or process. In one embodiment, these methods or processes can be implemented by a computer program product contained in a computer-readable medium, and the computer program product includes computer-executable instructions, such as program code, executed by a computer in a network environment. As described above, memory and/or computer-readable media can include removable and non-removable storage devices, including but not limited to read-only memory (ROM), random access memory (RAM), compact disc (CD), digital versatile disc (DVD), etc. When implemented in software, these functions can be stored or transmitted as one or more instructions or codes on a computer-readable medium. Computer-readable media includes both computer storage media and communication media, and communication media includes any medium that is convenient for transmitting a computer program from one location to another. The storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer. By way of example, and not limitation, such computer-readable media may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code modules in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor.

In addition, any connection is appropriately referred to as a computer-readable medium. For example, if a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) is used to send software from a website, server, or other remote source, the coaxial cable, fiber optic cable, twisted pair, DSL are included in the definition of medium. Disk and disc used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, wherein disks often reproduce data magnetically, while discs reproduce data optically by laser. Combinations of the above media should also be included within the scope of computer-readable media.

Generally, program modules may include routines, programs, objects, components, data structures, etc., which perform specific tasks or implement abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of program code for executing the methods disclosed herein. The specific sequence of these executable instructions or associated data structures represents an example of corresponding operations for implementing the functions described in these steps or processes.

The various exemplary logics, logic blocks, modules, and circuits described in conjunction with the solutions disclosed herein may be implemented or executed using a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a combination of multiple microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration. In addition, at least one processor may include one or more modules operable to perform one or more of the steps and/or operations described above.

For software implementation, the techniques described herein can be implemented using modules (e.g., procedures, functions, etc.) that perform the functions described herein. The software code can be stored in a memory unit and can be executed by a processor. The memory unit can be implemented within the processor or external to the processor. In the case of an external processor, the memory unit can be communicatively coupled to the processor by various methods known in the art. In addition, at least one processor can include one or more modules operable to perform the functions described herein.

The techniques described herein can be used in various wireless communication systems, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms "system" and "network" are often used interchangeably. A CDMA system can implement radio technologies such as Universal Terrestrial Radio Access (UTRA) and CDMA2000. UTRA includes Wideband CDMA (W-CDMA) and other variants of CDMA. In addition, CDMA2000 covers the IS-2000, IS-95, and IS-856 standards. A TDMA system can implement radio technologies such as Global System for Mobile Communications (GSM). An OFDMA system can implement radio technologies such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-Telecom, and others. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) is a version of UMTS that uses E-UTRA, which utilizes OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTE, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). Additionally, CDMA2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). Furthermore, these wireless communication systems may include peer-to-peer (e.g., user device-to-user device) ad hoc network systems, often using unpaired, unlicensed spectrum, 802.xx wireless LAN, Bluetooth, and any other short-range or long-range wireless communication technology.

Single-carrier frequency division multiple access (SC-FDMA) is a technique that can be used in conjunction with the disclosed embodiments and utilizes single-carrier modulation and frequency-domain equalization. SC-FDMA offers similar performance and substantially similar overall complexity to OFDMA systems. Due to the inherent single-carrier structure of SC-FDMA signals, SC-FDMA signals have a lower peak-to-average power ratio (PAPR). SC-FDMA can be used in uplink communications, where a lower PAPR significantly benefits user devices in terms of transmit power efficiency.

In addition, the various schemes or features described herein can be implemented as methods, devices or products using standard programming and/or engineering techniques. The term "product" as used herein is intended to include computer programs that can be accessed from any computer-readable device, carrier or medium. For example, computer-readable media can include, but are not limited to, magnetic storage devices (e.g., hard disks, floppy disks, magnetic strips, etc.), optical disks (e.g., compact disks (CDs), digital versatile disks (DVDs), etc.), smart cards, and flash memory devices (e.g., EPROMs, cards, sticks, key drives, etc.). In addition, the various storage media described herein can represent one or more devices and/or other machine-readable media for storing information. The term "machine-readable medium" can include, but is not limited to, wireless channels and various other media capable of storing, containing and/or carrying instructions and/or data. In addition, a computer program product can include a computer-readable medium having one or more instructions or codes that are operable to cause a computer to perform the functions described herein.

In addition, the steps and/or operations of the methods or algorithms described in conjunction with the solutions disclosed herein may be directly embodied as hardware, software modules executed by a processor, or a combination of the two. The software modules may be located in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium may be coupled to the processor so that the processor can read information from and write information to the storage medium. Alternatively, the storage medium may be integrated into the processor. Furthermore, in some embodiments, the processor and storage medium may be located in an ASIC. Alternatively, the ASIC may be located in a user device (e.g., UE 830 in FIG. 8 ). Alternatively, the processor and storage medium may be located as discrete components in a base station (e.g., base station 810 in FIG. 8 ). Furthermore, in some embodiments, the steps and/or operations of the methods or algorithms may be located as one or any combination of code sets and/or instruction sets on a machine-readable medium and/or computer-readable medium, which may be included in a computer program product.

Although the above disclosure discusses a number of exemplary embodiments, it should be noted that various changes and modifications may be made without departing from the scope of the described embodiments as defined by the appended claims. Accordingly, the described embodiments are intended to encompass all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, although elements of the described embodiments are described or claimed in the singular, the plural is contemplated unless expressly limited to the singular. Furthermore, all or part of any embodiment may be used together with all or part of any other embodiment unless otherwise stated.

With respect to the extension of the word "comprising" as used in the detailed description or the claims, the word is intended to mean inclusive, with a meaning similar to the word "including" when used as a transitional word in a claim. Furthermore, the word "or" as used in the detailed description or the claims is intended to mean an inclusive "or" rather than an exclusive "or." That is, unless specified otherwise or clear from the context, "X employs A or B" is intended to mean any inherently inclusive permutation. That is, the phrase "X employs A or B" is satisfied in any of the following instances: X employs A; X employs B; or X employs both A and B. Furthermore, the articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more," unless specified otherwise or clear from the context to refer to the singular.

Claims (36)

1. A communication method, comprising: A virtual cell identifier is transmitted from the serving cell in a Cooperative Multipoint (CoMP) transport network, wherein the virtual cell identifier is different from the serving cell identifier of the serving cell; The UE-RS sequence generator is initialized at least in part based on the virtual cell identifier; A UE-RS sequence is generated using the already initialized UE-RS sequence generator, and the UE-RS sequence is associated with the virtual cell identifier; and The UE-RS is transmitted at least in part based on the UE-RS sequence. 2. The method of claim 1, further comprising: Transmit the serving cell identifier. 3. The method of claim 2, further comprising: The scrambling sequence generator is initialized at least in part based on the serving cell identifier; A scrambling sequence is generated using the scrambling sequence generator, and the scrambling sequence is associated with the serving cell identifier; and Scrambled data is generated at least in part based on the scrambled sequence. 4. The method of claim 2, further comprising: The UE-RS sequence generator is initialized at least in part based on the serving cell identifier; A second UE-RS sequence is generated using the UE-RS sequence generator, the second UE-RS sequence being associated with the serving cell identifier; and The second UE-RS is generated at least in part based on the second UE-RS sequence. 5. The method of claim 1, wherein the UE-RS is generated without a UE identifier. 6. The method of claim 1, further comprising: Data scrambled using a scrambling sequence is transmitted on the Physical Downlink Shared Channel (PDSCH), wherein the scrambling sequence is at least partially based on the serving cell identifier. 7. The method of claim 1, further comprising: Transmit a virtual UE identifier from the serving cell. 8. The method of claim 1, further comprising: Transmit codeword index and transmission time slot index from the serving cell. 9. The method of claim 8, wherein, The codeword index includes one of the serving cell codeword index and the virtual codeword index, and The transmission time slot index includes one of the serving cell transmission time slot index and the virtual transmission time slot index. 10. A communication device, comprising: Processor; and The memory includes processor-executable instructions that, when executed by the processor, configure the communication device: A virtual cell identifier is transmitted from the serving cell in a Cooperative Multipoint (CoMP) transport network, wherein the virtual cell identifier is different from the serving cell identifier of the serving cell; The UE-RS sequence generator is initialized at least in part based on the virtual cell identifier; The UE-RS sequence is generated using the UE-RS sequence generator, and the UE-RS sequence is associated with the virtual cell identifier; and The UE-RS is transmitted at least in part based on the UE-RS sequence. 11. The communication device of claim 10, wherein the memory further includes processor-executable instructions, which, when executed by the processor, configure the communication device: Transmit the serving cell identifier of the serving cell. 12. The communication device of claim 11, wherein the memory further includes processor-executable instructions, which, when executed by the processor, configure the communication device: The scrambling sequence generator is initialized at least in part based on the serving cell identifier; A scrambling sequence is generated using the scrambling sequence generator, and the scrambling sequence is associated with the serving cell identifier; and Scrambled data is generated at least in part based on the scrambled sequence. 13. The communication device of claim 11, wherein the memory further includes processor-executable instructions that, when executed by the processor, configure the communication device: The UE-RS sequence generator is initialized at least in part based on the serving cell identifier; A second UE-RS sequence is generated using the UE-RS sequence generator, the second UE-RS sequence being associated with the serving cell identifier; and The second UE-RS is generated at least in part based on the second UE-RS sequence. 14. The communication device of claim 10, wherein the UE-RS is generated without a UE identifier. 15. The communication device of claim 10, wherein the memory further includes processor-executable instructions, which, when executed by the processor, configure the communication device: Data scrambled using a scrambling sequence is transmitted on the Physical Downlink Shared Channel (PDSCH), wherein the scrambling sequence is at least partially based on the serving cell identifier. 16. The communication device of claim 10, wherein the memory further includes processor-executable instructions that, when executed by the processor, configure the communication device: Transmit the virtual UE identifier. 17. The communication device of claim 10, wherein the memory further includes processor-executable instructions that, when executed by the processor, configure the communication device: Transmit codeword index and transmission time slot index from the serving cell. 18. The communication device as claimed in claim 17, wherein, The codeword index includes one of the serving cell codeword index and the virtual codeword index, and The transmission time slot index includes one of the serving cell transmission time slot index and the virtual transmission time slot index. 19. A non-transitory computer-readable storage medium storing computer-executable program code, said computer-executable program code, when executed by a computer, causes the computer to perform the following steps: A virtual cell identifier is transmitted from the serving cell in a Cooperative Multipoint (CoMP) transport network, wherein the virtual cell identifier is different from the serving cell identifier of the serving cell; The UE-RS sequence generator is initialized at least in part based on the virtual cell identifier; A UE-RS sequence is generated using the already initialized UE-RS sequence generator, and the UE-RS sequence is associated with the virtual cell identifier; The UE-RS is generated at least in part based on the UE-RS sequence; and The UE-RS is transmitted at least in part based on the UE-RS sequence. 20. The non-transitory computer-readable storage medium of claim 19, wherein, when executed by the computer, the computer-executable program code further causes the computer to perform the following steps: Transmit the serving cell identifier. 21. The non-transitory computer-readable storage medium of claim 20, wherein, when executed by the computer, the computer-executable program code further causes the computer to perform the following steps: The scrambling sequence generator is initialized at least in part based on the serving cell identifier; A scrambling sequence is generated using the scrambling sequence generator, and the scrambling sequence is associated with the serving cell identifier; and Scrambled data is generated at least in part based on the scrambled sequence. 22. The non-transitory computer-readable storage medium of claim 20, wherein, when executed by the computer, the computer-executable program code further causes the computer to perform the following steps: The UE-RS sequence generator is initialized at least in part based on the serving cell identifier; A second UE-RS sequence is generated using the UE-RS sequence generator, the second UE-RS sequence being associated with the serving cell identifier; and The second UE-RS is generated at least in part based on the second UE-RS sequence. 23. The non-transitory computer-readable storage medium of claim 19, wherein the UE-RS is generated without a UE identifier. 24. The non-transitory computer-readable storage medium of claim 19, wherein, when executed by the computer, the computer-executable program code further causes the computer to perform the following steps: Data scrambled using a scrambling sequence is transmitted on the Physical Downlink Shared Channel (PDSCH), wherein the scrambling sequence is at least partially based on the serving cell identifier. 25. The non-transitory computer-readable storage medium of claim 19, wherein, when executed by the computer, the computer-executable program code further causes the computer to perform the following steps: Transmit a virtual UE identifier from the serving cell. 26. The non-transitory computer-readable storage medium of claim 19, wherein, when executed by the computer, the computer-executable program code further causes the computer to perform the following steps: Transmit codeword index and transmission time slot index from the serving cell. 27. The non-transitory computer-readable storage medium of claim 26, wherein, The codeword index includes one of the serving cell codeword index and the virtual codeword index, and The transmission time slot index includes one of the serving cell transmission time slot index and the virtual transmission time slot index. 28. A communication device for a serving cell in a Cooperative Multipoint (CoMP) transmission network, comprising: A module for transmitting a virtual cell identifier from the serving cell, wherein the virtual cell identifier is different from the serving cell identifier of the serving cell; A module for initializing a User Equipment (UE) Reference Signal (UE-RS) sequence generator based at least in part on the virtual cell identifier; A module for generating a UE-RS sequence using the already initialized UE-RS sequence generator, the UE-RS sequence being associated with the virtual cell identifier; and A module for transmitting UE-RS based at least in part on the UE-RS sequence. 29. The communication device of claim 28, further comprising: A module used to transmit the serving cell identifier. 30. The communication device of claim 29, further comprising: A module for initializing a scrambling sequence generator based at least in part on the serving cell identifier; A module for generating a scrambling sequence using the scrambling sequence generator, the scrambling sequence being associated with the serving cell identifier; and A module for generating scrambled data based at least in part on the scrambled sequence. 31. The communication device of claim 29, further comprising: A module for initializing the UE-RS sequence generator based at least in part on the serving cell identifier; A module for generating a second UE-RS sequence using the UE-RS sequence generator, the second UE-RS sequence being associated with the serving cell identifier; and A module for generating a second UE-RS based at least in part on the second UE-RS sequence. 32. The communication device of claim 28, wherein the UE-RS is generated without a UE identifier. 33. The communication device of claim 28, further comprising: A module for transmitting data scrambled using a scrambling sequence on a Physical Downlink Shared Channel (PDSCH), wherein the scrambling sequence is at least partially based on the serving cell identifier. 34. The communication device of claim 28, further comprising: A module for transmitting a virtual UE identifier from the serving cell. 35. The communication device of claim 28, further comprising: A module for transmitting codeword indexes and transmission time slot indexes from the serving cell. 36. The communication device as described in claim 35, wherein, The codeword index includes one of the serving cell codeword index and the virtual codeword index, and The transmission time slot index includes one of the serving cell transmission time slot index and the virtual transmission time slot index.