Multi-antenna configuration signaling in wireless communication system

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DESCRIPTION

Multi-antenna configuration signaling in a wireless communication system

FIELD OF DESCRIPTION

The present description relates generally to wireless communications and more particularly to multi-antenna configuration signaling in wireless communication systems.

BACKGROUND

In 3GPP, the Long Term Evolution (LTE) of Mobile Telecommunications Systems (UMTS - Mobile Telecommunications Systems) is expected to allow up to 4 antenna ports to be defined for the multi-antenna base station transmissions and allowing the use of 1, 2, or 4 antenna ports for selected physical channel transmissions. The Physical Broadcast Channel (PBCH) can be transmitted using all three of these last antenna port configurations. Since the base station does not explicitly signal the antenna configuration via the sync channel, the user equipment (UE - User Equipment) is required to decode the PBCH without the assistance of the antenna configuration information. of the base station obtained during a previous phase of the initial network access procedure. In particular, the Master Information Block born in the PBCH is transmitted as a convolutionally encoded key with a cyclic redundancy check (CRC - Cyclic Redundancy Check, in English), but it is possible even at higher signal-to-noise ratios than the UE. fail to identify the number of antennas present solely by inspecting the common Reference Symbols (RSs). Similarly, the UE may misidentify the base station antenna configuration when hypothesizing the transmission diversity scheme associated with each allowed antenna configuration in combination with a CRC test of the PBCH. For example, when transmitting using the specified 2-antenna transmission diversity scheme of Space-Frequency Block Coding (SFBC), a UE can correctly decode the PBCH key when an assumption is made (incorrectly) about transmission with 1 antenna.

3GPP R1-073970 describes several possible approaches for communicating base station antenna configuration information for corresponding PBCH transmissions. In one approach, the mapping of the PBCH key to oFdM symbols and subcarriers (ie, resource elements) is changed according to the multi-antenna configuration. The 3GPP document R1-074861 suggests, however, that the mapping of the PBCH key on resource elements should not vary with the antenna configuration. According to a second approach, the PBCH key is scrambled with different scramble sequences, in which the sequence is conditioned by the antenna configuration of the base station. This approach requires the UE to descramble the Log Likelyhood Ratios (LLRs) arising from each hypothetical multi-antenna configuration before attempting convolutional decoding and CRC checking. In this second approach, a descrambling operation is required for each antenna configuration scenario. A third approach requires changing the Alamouti code (SFBC or SFBC + FSTD) according to the antenna configuration. This would require the UE to support more transmit diversity mapping configurations. Accordingly, going a little further, a low complexity means is needed to assist the UE in discriminating the antenna configuration.

3GPP's "Antenna Configuration Detection Based on Reference Signal Energy", R1-080434 by Motorola, and 3GPP's "Issues with PBCH-based Blind Antenna Configuration Detection", R1-080324 describe similar methods.

The various aspects, features, and advantages of the description will become more fully apparent to those not skilled in the art upon careful consideration of the following Detailed Description thereof with the accompanying drawings described below. Drawings may have been simplified for clarity and are not necessarily drawn to scale.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication system.

FIG. 2 is a block diagram of a wireless communication infrastructure entity.

FIG. 3 is a process flow diagram of the wireless communication infrastructure entity.

FIG. 4 is a block diagram of a wireless communication user terminal.

FIG. 5 is a process flow diagram of a wireless communication user terminal.

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DETAILED DESCRIPTION

In FIG. 1, a wireless communication system 100 comprises one or more fixed-base infrastructure units that form a distributed network over a geographic region. The base unit may also be referred to as an access point, access terminal, base, base station, Node B, eNode B, or other terminology used in the industry. In FIG. 1, the one or more base units 101 and 102 serve a number of remote units 103 and 110 within a service area, eg, a cell or a cell sector. Remote units can be fixed units or mobile terminals. Remote units may also be referred to as subscriber units, mobiles, mobile phone stations, users, terminals, subscriber stations, user equipment (UE), terminals, or other terminology used in the industry.

Generally, the base units 101 and 102 transmit downlink communication signals 104 and

105 to service remote units in the time and / or frequency domain. Remote units 103 and 110 communicate with one or more base units via uplink communication signals

106 and 113. The one or more base units may comprise one or more transmitters and one or more receivers for the downlink and uplink transmissions. The remote units can also comprise one or more transmitters and one or more receivers.

In one implementation, the wireless communication system complies with the Long Term Evolution (LTE) development of the Universal Mobile Telecommunications System (UMTS) protocol. of 3GPP, in which the base station transmits using an orthogonal frequency division multiplexing modulation (OFDM) scheme, in English) on the downlink and user terminals transmit on the uplink using a Single Carrier-Frequency Division Multiple Access (SC-FDMA) scheme. More generally, however, the wireless communication system may implement some other open or proprietary communication protocol. The present description is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

In some systems, each base station, and more generally some other wireless communication infrastructure entity, has a communication configuration. In one example, the communication configuration is a base station antenna configuration. In 3GPP, for example, the Long Term Evolution (LTE) of Universal Mobile Telecommunications Systems (UMTS) is expected to allow up to 4 antenna ports are defined by multi-antenna base station transmissions and allow 1, 2 or 4 antenna ports to be used for selected physical channel transmissions. The Physical Broadcast Channel (PBCH) can be transmitted using all three of these last antenna port configurations. Thus, the multiple base stations that make up a wireless communication system can potentially have different antenna configurations. Also, in some system implementations, the antenna configuration of the one or more base terminals changes dynamically.

In 3GPP, currently, the UE is requested to decode the PBCH without the assistance of the base station antenna configuration information acquired during a previous phase of the initial network access procedure, since the base station does not signal explicitly the antenna configuration via the sync channel. Accordingly, a means is desired in some cases to assist the UE in discriminating the base station antenna configuration, particularly when neighboring base stations have different configurations and / or when the antenna configuration of the base station. base changes dynamically. There may also be cases where it is desirable for the base station to signal the transmitting antenna configuration that should be adopted by the terminal.

The present description is not intended to be limited to communicating or assisting a user terminal in determining the antenna configuration of a particular base unit. More generally, the wireless communication infrastructure entity may assist one or more entities with determining the communication configuration of the wireless communication infrastructure entity or with determining the communication configuration of or for the wireless terminal. . For example, the communication configuration information may be in the form of any of or more of the following: the antenna configuration of the wireless communication terminal, information about the cell identity information (this may sometimes be transferred by association, eg with a sync channel identifier); information regarding the duration of a frame or the structure of an interval; the cell configuration as a paired transmission (for example, Frequency Division Duplexing, FDD) or unpaired (for example, Time Division Duplexing, TDD) )); symmetric or asymmetric downlink and uplink frequency resources; the type and / or number of pilot or reference symbols transmitted; whether a broadcast or unicast service is supported; the presence of overlapping channel transmissions; admission control data; spectrum association

ES 2 397 686 T3 adjacent or non-adjacent; the number of accessible carriers or carrier ratios in the case of a multi-carrier structure; the cell and carrier type and the relationship to other cells in a hierarchical cell structure or multi-carrier hierarchical cell structure; a dedicated broadcast carrier in an SFN; among other information.

In FIG. 2, a wireless communication infrastructure entity 200 having a communication configuration comprises a transceiver 210 communicatively coupled to a controller 200. In one embodiment, the wireless communication infrastructure entity corresponds to one of the base units of FIG. . 1, in which the communication configuration is an antenna configuration. The transceiver generally communicates with one or more user terminals within its coverage area. In FIG. 2, the controller is very easily implemented as a software and / or firmware controlled digital processor stored in memory 230. Alternatively however, the controller may be implemented as a hardware equivalent device or as a combination of hardware and software. The controller includes a parity bit generation functionality 222 used to generate parity bits based on a word of information that must be transmitted to a user terminal. Thus, under the control of software and / or firmware, the controller is configured to generate parity bits based on an information word. In flow chart 300 of the process of FIG. 3, at 310, the communication network infrastructure entity generates parity bits, for example, Cyclic Redundancy Check (CRC) bits based on an information word, for example, a block of transport. In FIG. 2, at 223, the parity bits are combined with the information word.

In FIG. 2, the controller includes a parity bit encoding functionality 224 used to encode the communication configuration information of the wireless communication infrastructure entity into the parity bits. The controller is configured to encode the parity bits based on the communication settings of the wireless communication infrastructure entity under the control of software and / or firmware. In other embodiments, more generally, other communication configuration information could be encoded on the parity bits. In one embodiment, the controller is configured to encode the parity bits by masking the parity bits with a single set of configuration indicator bits corresponding to the communication configuration of the wireless communication infrastructure entity. In one implementation, masking can be accomplished by XORing the parity bits with the set of configuration flag bits. The mask could be generated, for example, by selecting 3 masking words of length N, where N is the length of the PBCH CRC parity field (and is probably 16 bits) with a maximum Hamming distance. Such a set of masking words could include, for example, the all-zero or null masking word corresponding to the 1 antenna configuration without loss of generality. By extending the number of states and therefore the number of applicable masks, any information regarding the antenna configuration of the base station could also be encoded.

The mask or parity field modifier could also be conditioned on the physical cell ID of the base station, or the duration of a frame or slot structure, or the configuration of the cell as paired transmission (e.g. duplexing Frequency Division Duplexing (FDD) or unpaired (for example, Time Division Duplexing, TDD), the symmetric or asymmetric downlink and uplink frequency resources, the type and number of pilot or reference symbols transmitted, the type of service supported (e.g., broadcast or unicast), the presence of overlapping channel transmissions, the admission control data, the association of adjacent or non-adjacent spectrum, the number of accessible carriers or carrier ratios in the case of a multi-carrier structure, the cell and the cell type and the relationship to other cells in a hierarchical cell structure or multi-carrier hierarchical cell structure; among other communication configuration information, some examples of which have been explained above.

The information word is generally combined or otherwise associated with the encoded parity bits prior to transmission to the user terminal. In one embodiment, the controller is configured to combine the information word and parity bits by concatenating the parity bits with the information word, for example, at the beginning or end of the information word, before or after the information bits. parity are hard-coded. Alternatively, the parity bits can be inserted into a middle portion of the information word or the parity bit can be interleaved with the information word before or after encoding.

In FIG. 3, at block 320, the wireless communication infrastructure entity combines the information word and parity bits and then at 330 encodes the parity bits based on the communication configuration of the wireless communication infrastructure entity. In an alternative embodiment, the parity bits are encoded first and then combined with the information word. Thus, in FIG. 2, the spatial location of the order combining functionality is not necessarily indicative of the order in which it occurs with respect to the parity bit encoding function. In some embodiments, in the

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FIG. 2, the controller includes channel encoding functionality used to encode the information word and encoded parity bits combined into one channel prior to transmission. In FIG. 3, at 340, the information word combined with the encoded parity bits are encoded into one channel prior to transmission at 350. In FIG. 2, the controller communicates the one-channel encoded information word and parity bits to the transceiver for transmission.

In FIG. 4, a wireless communication user terminal 400 comprises a transceiver 410 communicatively coupled to a controller 420. In one embodiment, the user terminal corresponds to one of the remote units of FIG. 1. The transceiver generally communicates with one or more base units. In FIG. 4, the controller is very easily implemented as a digital processor controlled by software and / or firmware stored in memory 430. Alternatively however, the controller may be implemented as a hardware equivalent device or as a combination of hardware and software. In flow chart 500 of the process of FIG. 5, at 510, the user terminal receives an information word combined with encoded parity bits from a wireless communication entity.

In FIG. 4, the controller includes functionality 422 used to identify a set of configuration flag bits used to encode parity bits that are combined with an information word. In FIG. 4, the controller also includes functionality 424 used to determine a communication configuration based on the set of configuration indicator bits used to encode the parity bits. In one embodiment, the controller is configured to determine a communication configuration of the wireless communication entity from which the combination of the information word and encoded parity bits were received based on the set of configuration indicator bits used to encode the parity bits. In another embodiment, the controller is configured to determine a communication configuration of the wireless communication user terminal based on the set of configuration indicator bits used to encode the parity bits.

In one implementation illustrated in FIG. 5, at 520, the user terminal retrieves the parity bits from the encoded parity bits. In one embodiment, the parity bits are recovered by XORing the encoded parity bits with a set of configuration indicator bits. At 530, the user terminal performs an information word error detection using the recovered parity bits. In one embodiment, the user terminal carries out the process of making an XOR for each possible set of configuration indicator bits, where the set of configuration indicator bits indicative of the communication configuration of the wireless communication entity corresponds to the set of configuration flag bits for which the errors detected in the information word are relatively low. For example, the detected errors can be zero or at least less than the detected errors associated with the flag bits of the other configuration. The communication configuration of the wireless communication entity is indicated by no more than one set of configuration indicator bits.

Although the present disclosure and the best modes thereof have been described in a manner that establishes ownership and enables non-skilled persons to make use of it, it should be understood and it will be apparent that modifications and variations can be made without departing from the scope of the invention, as defined by the appended claims.

What is claimed is: