Source: http://www.google.com/patents/US7965785?dq=6,826,762
Timestamp: 2014-03-10 01:09:42
Document Index: 607259995

Matched Legal Cases: ['application No. 60', 'art 16', 'art 16', 'art 16', 'art 16', 'art 16', 'art 16', 'art 16', 'art 16', 'art 16', 'art 16', 'art 16', 'art 16', 'art 16', 'art 16']

Patent US7965785 - Uplink multiple-input-multiple-output (MIMO) and cooperative MIMO transmissions - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA method is provided for MIMO uplink communications between a base station and a wireless station with more than two antennae. The method includes: (a) negotiating between the base station and the wireless station uplink MIMO/cooperative MIMO capabilities, using a message exchange protocol in which a...http://www.google.com/patents/US7965785?utm_source=gb-gplus-sharePatent US7965785 - Uplink multiple-input-multiple-output (MIMO) and cooperative MIMO transmissionsAdvanced Patent SearchPublication numberUS7965785 B2Publication typeGrantApplication numberUS 11/930,600Publication dateJun 21, 2011Filing dateOct 31, 2007Priority dateApr 4, 2007Also published asCN102017446A, EP2132946A2, US20080247488, WO2008124535A2, WO2008124535A3Publication number11930600, 930600, US 7965785 B2, US 7965785B2, US-B2-7965785, US7965785 B2, US7965785B2InventorsAnxin Li, Xiangming Li, Hidetoshi Kayama, Ismail Guvenc, Moo Ryong JeongOriginal AssigneeNtt Docomo, Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (8), Non-Patent Citations (11), Referenced by (5), Classifications (10), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetUplink multiple-input-multiple-output (MIMO) and cooperative MIMO transmissionsUS 7965785 B2Abstract A method is provided for MIMO uplink communications between a base station and a wireless station with more than two antennae. The method includes: (a) negotiating between the base station and the wireless station uplink MIMO/cooperative MIMO capabilities, using a message exchange protocol in which a message exchanged comprises a field for specifying uplink MIMO/cooperative MIMO capabilities; (b) the base station receiving a request from the wireless station for data transmission; (c) the base station sending the wireless station an allocated resource and an uplink MIMO/cooperative MIMO method for uplink transmission; (e) the wireless station mapping data symbols to the allocated resource with proper pilot pattern; and (f) the base station detecting the data symbols from the channel.
CROSS REFERENCE TO RELATED APPLICATIONS The present application claims priority of U.S. provisional patent application No. 60/910,151, filed Apr. 4, 2007, incorporated herein by reference.
MIMO and cooperative MIMO techniques enhance system performance in a wireless communication system (e.g., a cellular network or an IEEE 802.16 network) by exploiting spatial domain freedom and signal processing techniques. MIMO and Cooperative MIMO techniques are described, for example, in the article �From theory to practice: an overview of MIMO space-time coded wireless systems,� by D. Gesbert, M. Shafi, and D. S. Shiu, IEEE J. Select. Areas Commun., vol. 21, no. 3, pp. 281-302, April 2003.
Certain wireless network standards (e.g., IEEE 802.16-20041 and IEEE 802.16e2) have adopted MIMO and cooperative MIMO techniques to enhance system performance. Other emerging wireless network standards (e.g., IEEE 802.16j3 and IEEE 802.16m4) are also considering including MIMO and cooperative MIMO techniques to improve system performance (e.g., high data rate or low BER (bit-error-rate)). 1 IEEE Standard for Local and Metropolitan area networks, Part 16: Air Interference for Fixed Broadband Wireless Access Systems. (October 2004)2 IEEE Standard for Local and metropolitan area networks Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems Amendment 2: Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands and Corrigendum 1. (February 2006)3 P802.16j PAR, P802.16j-Amendment to IEEE Standard for Local and Metropolitan Area Networks�Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems�Multihop Relay Specification. (March 2006; see, e. http://standards.ieee.org/board/nes/projects/802-16j.pdf)4 P802.16m P802.16�IEEE Standard for Local and metropolitan area networks�Part 16: Air Interface for Fixed Broadband Wireless Access Systems�Amendment: IEEE Standard for Local and metropolitan area networks�Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems�Advanced Air Interface (see, e.g., http://standards.ieee.org/board/nes/projects/802-16m.pdf) (December 2006)
(a) a wireless station (WS) negotiates with a base station (BS) regarding the uplink MIMO/cooperative MIMO capabilities that may be used in its transmissions; (b) the WS sends a request to the BS for uplink transmission when the WS has data to be transmitted; (c) the BS determines the uplink MIMO/cooperative MIMO method (e.g., stream number, STFC matrix, antenna grouping method, and precoding matrix) to be used by the WS, according to the BS's measurement of its channel, the bandwidth requests of the wireless stations, and other parameters; (d) through an �Information Element� (IE), the BS informs the WS of the resource allocated to the uplink transmission and the MIMO/cooperative MIMO method for the uplink transmission to be used by the WS; (e) the WS maps data symbols and pilot symbols to the allocated resource, according to pre-defined data mapping rules and pilot patterns indicated in the IE, and performs the MIMO/cooperative MIMO transmissions using the allocated resource; and (f) the BS performs channel estimation and signal detection to detect the received data. In general, negotiation for the uplink MIMO/cooperative MIMO can be performed when the WS enters the network. The MIMO/cooperative MIMO capabilities refer to such capabilities as supported STFC matrices, antenna selection ability, antenna grouping ability, precoding ability, vertical coding ability, or horizontal coding ability. Under the IEEE 802.16-2004 and the IEEE 802.16e standards, subscriber station basic capability request (�SBC-REQ�) and subscriber station basic capability response (�SBC-RSP�) messages are used by a WS and a BS to negotiate the uplink MIMO/cooperative MIMO capabilities.
Examples of IEs used between a BS and a WS under the IEEE 802.16-2004 and IEEE 802.16e standards for communicating the resource allocation and uplink MIMO/cooperative MIMO method include MIMO uplink basic IE (�MIMO_UL_Basic_IE�) and MIMO uplink enhanced IE (�MIMO_UL_Enhanced_IE�). Since MIMO_UL_Enhanced_IE encompasses more functions than MIMO_UL_Basic_IE, the following detailed description uses MIMO_UL_Enhanced_IE to illustrate the present invention. FIG. 3 shows the format for a MIMO_UL_Enhanced_IE. As shown in FIG. 3, the Matrix_Indicator (MI) field specifies the MIMO method to be used for uplink transmission. For a WS station with dual antennae, the MI field specifies an STTD matrix. For a WS with a single antenna, the MI field is ignored. The Pilot Pattern Indicator (PI) field specifies a pilot pattern to be used by a WS in an uplink transmission. Thus, as is apparent from FIG. 3, the MIMO_UL_Enhanced_IE supports only MIMO/cooperative MIMO methods for WS's with two or less antennae. New methods should be developed for resource allocation and MIMO/cooperative MIMO methods that support a WS with more than two antennae.
In step (e) discussed above, a WS uses the MIMO coding matrix specified in the IE to perform MIMO encoding, and to map the coded data symbols to the allocated resource with a proper pilot pattern. The uplink basic resource unit is named a �tile,� one example of which is shown in FIG. 4. As shown in FIG. 4, a tile includes 12 subcarriers, four of which encode pilot symbols (i.e., the other eight subcarriers used for encoding data symbols). The tile is over three OFDMA symbols in the time domain and over four subcarries in the frequency domain. For uplink transmissions, a WS maps the coded data symbols to the tile. FIGS. 5 and 6 show the data mapping rules for 2-antenna STTD under the IEEE 802.16-2004 standard and the IEEE 802.16e standard, respectively. As shown in FIGS. 5 and 6, the frequency axis has a higher priority than time axis, (i.e. the coded data symbol first maps to the subcarriers within the tile and then to different OFDM symbols within the tile).
As is apparent from the above detailed descriptions of the uplink MIMO/cooperative MIMO transmission procedures in the IEEE 802.16-2004 and the IEEE 802.16e standards, the IEEE 802.16-2004 and IEEE 802.16e standards cannot support uplink MIMO/cooperative MIMO transmissions for a WS with more than two antennae. However, with the rapid development of the MIMO techniques, WS's with three or four antennae have become common place. For example, a relay station (RS) in an IEEE 802.16j network typically has three or four antennae (see, e.g., IEEE 802.16j-06/015, �Harmonized Contribution on 802.16j (Mobile Multihop Relay) Usage Models�). Under the IEEE 802.16m standard, a mobile station (MS) may also have three or four antennae. Thus, on one hand, current IEEE 802.16-2004 and IEEE 802.16e standards do not support WS's with three or four antennae, and no implementation is known for uplink MIMO/cooperative MIMO transmissions for a WS with three or four antennae. On the other hand, such an implementation is required by the IEEE 802.16j and IEEE 802.16m standards, for example.
(a) methods for a WS with three or four antennae to negotiate MIMO/cooperative MIMO capabilities with a BS; (b) concrete MIMO/cooperative MIMO methods for uplink transmissions of a WS with three or four antennae; (c) methods for informing a WS of the uplink MIMO/cooperative MIMO methods to be used and the allocated resource; and (d) a pilot pattern to be used by a WS with different transmission antenna, and data mapping rules to map data symbols after MIMO encoding to the tile. SUMMARY According to one embodiment of the present invention, a method is provided for MIMO uplink communications between a base station and a wireless station. The method includes: (a) negotiating between the base station and the wireless station uplink MIMO/cooperative MIMO capabilities, using a message exchange protocol in which a message exchanged comprises a field for specifying uplink MIMO/cooperative MIMO capabilities; (b) the base station receiving a request from the wireless station for data transmission; (c) the base station sending the wireless station an allocated resource and an uplink MIMO/cooperative MIMO method for uplink transmission; (e) the wireless station mapping data symbols to the allocated resource with proper pilot pattern; and (f) the base station detecting the data symbols from the channel.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an exemplary uplink transmission under the IEEE 802.16-2004 standard or the IEEE 802.16e network standard.
FIG. 4 shows one example of the uplink basic resource unit �tile.�
DESCRIPTION OF PREFERRED EMBODIMENTS The present invention provides, in a wireless network, support for WS's with more than two antennae. FIG. 7 shows an exemplary uplink transmission in an IEEE 802.16j network having a WS (e.g., a relay station) with three or four antennae, in accordance with one embodiment of the present invention. Similarly, FIG. 8 shows an exemplary uplink transmission in an IEEE 802.16m network (or another wireless network), in which wireless stations with 1-4 antennae are supported, in accordance with one embodiment of the present invention. To support an uplink MIMO/cooperative MIMO transmission by a WS with more than two antennae, the present invention provides new functions, such as:
(a) methods for wireless station with three or four antennae to negotiate its MIMO/cooperative MIMO capabilities with a BS; (b) concrete MIMO/cooperative MIMO methods for uplink transmissions by a wireless station with three or four antennae; (c) methods for informing a WS of the uplink MIMO/cooperative MIMO methods to be used and the allocated resource; (d) pilot patterns to be used by WS's with different transmission antennae; and (e) data mapping rules to map data symbols, after MIMO encoding to the tile. FIG. 9 illustrates a procedure for uplink MIMO/cooperative MIMO transmissions, in accordance with one embodiment of the present invention. As shown in FIG. 9, at step 901, a WS having three or four antennae negotiates with a BS for uplink MIMO/cooperative MIMO capabilities, using SBC-REQ and SBC-RSP messages, similar to those defined for the IEEE 802.16-2004 and the IEEE 802.16e standards, but including the TLV field shown in FIG. 10. FIG. 10 shows a TLV field defined for SBC-REQ and SBC-RSP messages which specifies the MIMO/cooperative MIMO capabilities for a WS having three or four antennae. As shown in FIG. 10, the TLV field specifies MIMO/cooperative MIMO capabilities including (a) STFC matrices for vertical coding and horizontal coding, (b) antennas selection, (c) antenna grouping, (d) preceding; and (e) MIMO/cooperative capabilities. In this embodiment, a set bit (i.e., bit value �1�) indicates that the corresponding capability is supported, while a reset bit (i.e., bit value �0�) indicates that the corresponding capability is not supported. In FIG. 10, bit #11 is set by the WS to inform the BS that the WS can support an uplink codebook-based precoding.
A 1 = [ S ~ 1 - S ~ 2 * 0 0 S ~ 2 S ~ 1 * S ~ 3 S ~ 4 * 0 0 S ~ 4 S ~ 3 * ] A 2 = [ S ~ 1 - S ~ 2 * S ~ 3 - S ~ 4 * S ~ 2 S ~ 1 * 0 0 0 0 S ~ 4 S ~ 3 * ] A 3 = [ S ~ 1 - S ~ 2 * 0 0 0 0 S ~ 3 - S ~ 4 * S ~ 2 S ~ 1 * S ~ 4 S ~ 3 * ] B 1 = [ s ~ 7 - s ~ 8 * s ~ 3 - s ~ 4 * s ~ 1 - s ~ 2 * s ~ 5 - s ~ 6 * s ~ 2 s ~ 1 * s ~ 6 s ~ 5 * ] B 2 = [ s ~ 1 - s ~ 2 * s ~ 5 - s ~ 6 * s ~ 7 - s ~ 8 * s ~ 3 - s ~ 4 * s ~ 2 s ~ 1 * s ~ 6 s ~ 5 * ] B 3 = [ ⁢ s ~ 1 - s ~ 2 * s ~ 5 - s ~ 6 * s ~ 2 s ~ 1 * s ~ 6 s ~ 5 * s ~ 7 - s ~ 8 * s ~ 3 - s ~ 4 * ] For SFTC, the MIMO coding matrices for a WS with four antennae are:
A 1 = [ S 1 - S 2 * 0 0 S 2 S 1 * 0 0 0 0 S 3 - S 4 * 0 0 S 4 S 3 * ] , ⁢ A 2 = [ S 1 - S 2 * 0 0 0 0 S 3 - S 4 * S 2 S 1 * 0 0 0 0 S 4 S 3 * ] , ⁢ A 3 = [ S 1 - S 2 * 0 0 0 0 S 3 - S 4 * 0 0 S 4 S 3 * S 2 S 1 * 0 0 ] . ⁢ B 1 = [ S 1 - S 2 * S 5 - S 7 * S 2 S 1 * S 6 - S 8 * S 3 - S 4 * S 7 S 5 * S 4 S 3 * S 8 S 6 * ] , ⁢ B 2 = [ S 1 - S 2 * S 5 - S 7 * S 2 S 1 * S 6 - S 8 * S 4 S 3 * S 8 S 6 * S 3 - S 4 * S 7 S 5 * ] , ⁢ B 3 = [ S 1 - S 2 * S 5 - S 7 * S 3 - S 4 * S 7 S 5 * S 2 S 1 * S 6 - S 8 * S 4 S 3 * S 8 S 6 * ] . ⁢ B 4 = [ S 1 - S 2 * S 5 - S 7 * S 4 S 3 * S 8 S 6 * S 2 S 1 * S 6 - S 8 * S 3 - S 4 * S 7 S 5 * ] , ⁢ B 5 = [ S 1 - S 2 * S 5 - S 7 * S 3 - S 4 * S 7 S 5 * S 4 S 3 * S 8 S 6 * S 2 S 1 * S 6 - S 8 * ] , ⁢ B 6 = [ S 1 - S 2 * S 5 - S 7 * S 4 S 3 * S 8 S 6 * S 3 - S 4 * S 7 S 5 * S 2 S 1 * S 6 - S 8 * ] . In precoding, the MIMO coding matrices for a WS with two antennas are:
For example, if the Matrix_Indicator field is set to 0, the Pilot Pattern Indicator field is set to 1 and the Matrix_Indicator_RS field is set to 10, a WS with three antennae refers to the MIMO coding matrix mapping table of FIG. 12 to determine that STFC matrix C for uplink MIMO transmissions is specified. Similarly, for these same bit values, a WS with four antennae refers to the MIMO coding matrix mapping table of FIG. 13 to determine that STFC matrix B4 for uplink MIMO transmissions is specified. Since each WS is identified by a different Connection Identifier (CID), the BS can select the proper MIMO coding matrix mapping table for the WS. As shown in FIG. 12, for example, the specification �Cn� denotes also antenna selection. �C1-one stream� denotes that only the first antenna is used, �C2-one stream� denotes that only the second antenna is used, �C3-one stream� denotes that only the third antenna is used, �C1-two streams� denotes that both the second and the third antennae are used, �C2-two streams� denotes that both the first and the third antennas are used, and �C3-two streams� denotes that both the first and the second antennae are used.
Alternatively, the BS may use a second method which uses a new MIMO uplink IE for a WS having more than two antennae. FIG. 14 shows one exemplary MIMO uplink IE (�MIMO_UL_Extended_IE�), according to one embodiment of the present invention. As shown in FIG. 14, a WS is first categorized according to the number of antennae to be used in the transmission, even if the actual number of antennae in the WS is greater. Thus, the antenna selection overhead is merged with the spatial multiplexing matrix, when a small number of antennae are used, resulting in a reduced total overhead. FIG. 15 illustrates an example of overhead reduction in merging the MIMO coding matrix of antenna selection for a 4-antenna WS, and the MIMO coding matrix of spatial multiplexing of a 3-antenna WS. In the example of FIG. 15, by setting the 4-bit Antenna_Indicator field in the uplink MIMO IE of FIG. 14 to 0b1101 (for a 4-antenna WS) or 0b1110 (for a 3-antenna WS), the antenna selection and the spatial multiplexing matrices can share one index.
The MIMO_UL_Extended_IE of FIG. 14 supports uplink MIMO/cooperative MIMO transmission for WS's with three or four antennae, provides high flexibility and can supports a large number of MIMO coding schemes, including STFC, antenna selection and grouping, and precoding. FIG. 16 summarizes the supported uplink MIMO/cooperative MIMO methods in the MIMO_UL_Extended_IE of FIG. 14. As shown in FIG. 16, the notation �C(m, n)� denotes two WS's, using m and n antennae, respectively, are involved in the uplink cooperative MIMO transmission. Similarly, the notation �C(m, n, p, q)� denotes four WS's, having m, n, p and q antennae, respectively, involved in an uplink cooperative MIMO transmission. FIG. 17 shows a cooperative MIMO transmission example that may be supported by the MIMO_UL_Extended_IE in an IEEE 802.16j network. In this example, in which WS 1 (i.e., RS1) and WS 2(i.e., RS 2) have four transmission antennae, the channel for WS 1 is line-of-sight (LOS), but can only support one data stream, and the channel for WS 2 is non-line-of-sight (NLOS), but can possible support one, two or three streams. In this instance, the BS first measures the channel for WS 2 to obtain the number of streams that may be supported by the channel. The BS can then specify for WS 1 and WS 2 cooperative MIMO transmissions using any of the C(1,1), C(1,2) and C(1,3) configurations. Such channel-aware cooperative MIMO transmissions improves greatly uplink spectrum efficiency.
( 4 8 ) = 8 ! 4 ! ⁢ ( 8 - 4 ) ! = 70 mapping rules are possible. The exemplary mapping rule of FIG. 19 has at least two advantages. First, the MIMO coded symbols are distributed evenly, so that spatial-time-frequency diversity gain can be maximized in a fast-changing channel, in terms of both time domain and frequency domain performance. Second, since the output symbols of the two MIMO coding matrices have the same mapping pattern, each MIMO coding matrix would have similar performance characteristics. Thus, balance performance of the two MIMO coding matrices may be achieved.
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