KR200430280Y1 - Multiple-in/multiple-out(mimo) wireless transmit/receive unit(wtru) for optimizing antenna mappings - Google Patents

Abstract

A multiple-input / multi-output (MIMO) wireless transmit / receive unit (WTRU) for selecting antenna mapping is disclosed. Antenna mapping is a combination of one antenna beam and one RF chain. A plurality of antennas are coupled to the beam selector, at least one of the plurality of antennas having beamforming capability. Multiple radio frequency (RF) chains are also coupled to the beam selector. The calibration unit is coupled to the beam selector to perform channel calibration of the selected antenna mapping. Preferably, the calibration unit includes a processor for calculating the channel estimation and calibration matrix, and a memory for storing the channel estimation and calibration matrix for later use. The beam selector is configured to select antenna mapping by selectively coupling one RF chain to one antenna beam based on the measured channel condition.

Antenna Mapping, Wireless Communication Networks, Calibration, Multiple Inputs and Outputs

Description

MULTIPLE-IN / MULTIPLE-OUT (MIMO) WIRELESS TRANSMIT / RECEIVE UNIT (WTRU) FOR OPTIMIZING ANTENNA MAPPINGS}

1 is a signal diagram of prior art channel calibration and packet data delivery.

2 is a flowchart of a method for selecting antenna mappings according to a preferred embodiment of the present invention.

3 is a block diagram of a system including an AP and a WTRU according to the present invention.

4 is a signal timing diagram of channel calibration and packet data transfer when antenna mapping selection according to the present invention is used.

5 illustrates a calibration training frame (CTF) PPDU frame format for implementing antenna mapping selection according to the present invention.

6 is a diagram illustrating an observation PPDU frame format for implementing antenna mapping selection according to the present invention.

7 is a diagram of an observation PPDU MAC frame format for implementing antenna mapping selection according to the present invention.

The present invention generally relates to a wireless communication system using multiple input / output (MIMO) technology, and more particularly, to selecting an optimal transmission setting for a MIMO capable multi-antenna array.

Wireless communication devices having multiple antennas arranged in a diversity configuration provide various transmission and reception advantages over devices having only a single antenna. The basis of diversity is to select for reception and transmission the antenna that shows the best reception at any given time. An apparatus using antenna diversity may have a plurality of physical antennas, but there is only one set of electronic circuits, ie, radio frequency (RF) chains, for processing signals.

Multiple input / output (MIMO) wireless technology uses multiple RF chains to improve antenna diversity. Each RF chain can receive or transmit simultaneously. This allows the MIMO device to achieve higher throughput and to address the negative effects of multipath interference. In the transmitting device, each RF chain is responsible for transmitting a spatial stream. A single frame can be decomposed and multiplexed over multiple spatial streams, which are then reassembled at the receiver.

MIMO is one of the most promising technologies in wireless communication. Unlike conventional smart antenna techniques aimed at mitigating adverse multipath fading and increasing the robustness of a single data stream, MIMO uses multipath fading to transmit and receive multiple data streams simultaneously. In theory, the performance of a MIMO system increases linearly with the number of transmit and receive antennas. MIMO is also being considered in multiple wireless data communication standards, such as IEEE 802.11n and third generation wideband code division multiple access (WCDMA).

In implementing MIMO, the WTRU may operate in either a spatial multiplexing mode or a spatial diversity mode. In spatial multiplexing mode, the WTRU may transmit multiple independent data streams to maximize data throughput. While in spatial diversity mode, the WTRU may transmit a single data stream via multiple antennas. Depending on the mode of operation, the WTRU is configured to select an appropriate quality metric or combination of quality metrics for use in the selection of the desired beam combination. Typically, the m × N channel matrix H can be obtained from the following form.

Here, the subscript in factor h represents the contribution due to each antenna mapping between antenna a ... m of transmit WTRU A and antenna a ... m of receive WTRU N.

The WTRU may obtain a calibration matrix K in a similar manner. In the context of wireless LANs, calibration involves calculating a complex set of correction coefficients, which, when antenna and subcarrier multiplexed in the baseband stream of the transmitting WTRU, reach an unknown constant across the antenna. Equalizes the response difference between the transmit and receive processing paths.

Referring to FIG. 1, a channel calibration signal diagram 100 of the prior art is shown. First, the transmitting WTRU (Tx WTRU) 110 needs to calibrate the existing channel between the receiving WTRUs (Rx WTRU) 120. The Tx WTRU 110 transmits a calibration training frame (CTF) 131 to the Rx WTRU 120. The Rx WTRU 120 responds by sending an Observed Physical Packet Data Unit (PPDU) 132. Tx WTRU 110 calculates channel estimate H 133 for the channel, referred to as H (2 → 1). Tx WTRU 110 transmits a calibration response 134 that includes the channel estimate H (2 → 1). Rx WTRU 120 performs channel estimation by sending CTF 135 to Tx WTRU 110. In response, the Tx WTRU 110 transmits an observation PPDU 136. Rx WTRU 120 calculates channel estimate H (1 → 2) and calculates calibration matrices K (1 → 2) and K (2 → 1) for channel 137. The Rx WTRU 12 then sends a calibration response 138 to the Tx WTRU 110 that includes a calibration matrix K (1 → 2). Note that this calibration matrix K (1 → 2) is then applied at Tx WTRU1 110 as the baseband gain or phase compensation factor for transmission to Rx WTRU 120. Calibration matrix K (2 → 1) is applied at Rx WTRU 120 again as baseband gain / phase correction factor when Rx WTRUs transmit signals to Tx WTRU 110. The channel is now calibrated and ready for packet exchange.

To initiate the data packet exchange, the Tx WTRU 110 sends a request 139 to the Rx WTRU 120, which responds by conveying a Modulation and Coding Technique (MCS) PPDU 140. . Tx WTRU 110 uses calibration matrix K (1 → 2) to calculate steering matrix V, and packet data transfer 142 begins.

Conventionally, the use of smart antenna technology has not been considered. Smart antennas, in particular beamforming, are signal processing techniques used in conjunction with transmitters or receivers that control the directivity of radiation patterns or their sensitivity. When receiving a signal, beamforming can increase the gain in the direction of the desired signals and reduce the gain in the interference and noise directions. When transmitting a signal, beamforming may increase the gain in the direction in which the signal is delivered. When beamable antennas are combined with MIMO, the number of available antenna mappings is greatly increased.

If beamforming antennas are included in the WTRU, the number of available antenna mappings can be very large. In order to optimize the communication link between two WTRUs, it is necessary to select the appropriate antenna mapping at both the transmitter and the receiver.

Therefore, what is needed is a method and apparatus for effectively utilizing the various antenna mappings available in a MIMO capable wireless device having a plurality of beamforming antennas.

The present invention is a multiple-input / multi-output (MIMO) wireless transmit / receive unit (WTRU) for selecting antenna mapping. Antenna mapping is a combination of one antenna beam and one RF chain. A plurality of antennas are coupled to the beam selector, at least one of the plurality of antennas having beamforming capability. Multiple radio frequency (RF) chains are also coupled to the beam selector. The calibration unit is coupled to the beam selector to perform channel calibration of the selected antenna mapping. Preferably, the calibration unit comprises a processor for calculating the channel estimation and calibration matrix, and a memory for storing the channel estimation and calibration matrix for later use. The beam selector is configured to select antenna mapping by selectively coupling one RF chain to one antenna beam based on the measured channel condition.

With reference to the embodiments described in the following specification and the accompanying drawings, a more detailed description of the invention will be made.

Although the features and elements of the present invention have been described as preferred embodiments in particular combinations, each feature and element may be used alone (without other features and elements of the preferred embodiment). Or in various combinations with or without other features and elements of the present invention.

In the following, a wireless transmit / receive unit (WTRU) includes, but is not limited to, user equipment, mobile stations, fixed or mobile subscriber units, pagers, or other types of devices capable of operating in a wireless environment. In the following, an access point (AP) includes, but is not limited to, a Node-B, a site controller, a base station, or other type of interface device in a wireless communication environment. As used herein, the term “antenna mapping” means a specific combination of antennas with a particular RF processing chain, or in the case of a beamforming antenna, a combination of antenna beams.

2, a method 200 of antenna mapping selection in accordance with the present invention is shown. The WTRU selects an antenna mapping from a candidate group of currently available antenna mappings (S210). The WTRU determines whether the selected antenna mapping has been calibrated (S220). If it is determined that the antenna mapping has not been calibrated, the WTRU calibrates the selected antenna mapping (S230). It should be noted that antenna mapping calibration already calibrated may be inadequate. Calibration of the selected antenna mapping will be described in more detail below. Next, the WTRU determines whether the receiving WTRU has changed its antenna mapping (S240). If the receiving WTRU has changed the antenna mapping, return to step S210 to select a new transmit antenna mapping, if desired. If it is determined that the receiving WTRU has not changed its antenna mapping, the transmitting WTRU starts packet data transmission using the selected and calibrated antenna mapping (S250). Return to step S210 to allow the transmitting WTRU to change its antenna mapping.

Referring to FIG. 3, there is shown a wireless communication system 300 including a first WTRU 310 and a second WTRU 320 for performing antenna mapping selection according to the present invention. In the following, the present invention will be described with reference to downlink transmission from the transmitting WTRU 310 to the receiving WTRU 320. However, the present invention is not only in the case where the WTRU 310 or the WTRU 320 is a base station, but also in the ad hoc or mesh network, even when the WTRU 310 communicates directly with the WTRU 320, the uplink and downlink Equally applicable to both communications.

The WTRU 310 includes two RF chains 312A, 312B, beam selectors 314, a plurality of antennas 316A-316n (where n is any integer greater than 1), and a calibration unit 318. do. In one embodiment of the present invention, the antennas 316A-316n may generate a plurality of beams. WTRU 320 includes two RF chains 322A, 322B, beam selector 324, and a plurality of antennas 326A-326m, where m is any integer greater than one. Again, in an embodiment of the present invention at least one of the antennas 326A-326m may generate a plurality of beams. With particular reference to the WTRU 320, according to the method 200 of the present invention described with reference to FIG. 2 above, the beam combination is selected by the beam selector 324 for MIMO transmission and reception. The selected antenna mapping is utilized for transmission and reception in accordance with the control signal output from the beam selector 324. The beam selector 324 selects a particular beam combination based on the quality metric generated and stored in the calibration unit 328, which will be described in detail below. The WTRU component of the present invention may be composed of a circuit including a plurality of components integrated or interconnected into an integrated circuit (IC). Although an embodiment of the present invention includes two RF chains, it is only for convenience of explanation, and it will be understood that other numbers of RF chains may be used.

For simplicity, FIG. 3 shows both the transmitting WTRU 310 and the receiving WTRU 320 installed in the beamforming antenna, each generating three (3) beams. However, the configuration shown in FIG. 3 is provided as an example, and is not limited thereto. Any combination of antenna types with any number of beams, or an antenna other than the beamforming or beamswitching type, may be used.

The antenna may be a switched parasitic antenna (SPA), a phased array antenna or any type of directional beamforming antenna. SPA is a reduced size, making it suitable for WLAN devices. If SPA is used, a single active antenna element coupled to one or more passive antenna elements may be used. The antenna beam pattern is adjusted by adjusting the impedance of the passive antenna element and the impedance adjustment can be performed by controlling a set of switches connected to the antenna element. In addition, the antenna may be a hybrid body having multiple antennas, all of which are omni-directional antennas. For example, three omnidirectional antennas with a selected physical spacing may be used for each antenna 326A-326m, which is controlled from the beam selector 324 to define different beam combinations. On and off can be switched according to the signal.

To illustrate, reference is made to FIG. 3. The transmitting WTRU 310 (also referred to herein as a Tx WTRU) has two RF chains 312A and 312B. Beam selector 314 couples several omni-directional antennas 316A-316n to RF chains 312A and 312B. Thus, the number of possible antenna mappings for the transmitter WTRU 310 is n times the number of RF chains. Receive WTRU 320 (also referred to herein as Rx WTRU) also has two RF chains 322A, 322B. Beam selector 124 couples multiple beamforming antennas 326A-326m to RF chains 322A, 322B. As discussed above, in this exemplary embodiment, each beamforming antenna 326A-326m may form three directional beams. Therefore, the receiving WTRU 120 has a total antenna mapping of m × number of beams × number of RF chains. The set of all possible antenna mappings that can be adopted for any transmitting station is called a "superset" and the size of the _superset is denoted by N _superset . N _superset Can be very large and may not be practical to use all possible antenna mapping at a given time.

The candidate set is a subset of the superset and a set of selectable antenna mappings at a given time. Preferably, the size of the candidate set is limited to antenna mapping between 8 and 32. The candidate set is not static but rather dynamic and can change over time to reflect changing channel conditions. For example, the transmitting station may monitor the channel conditions of all antenna mappings in the candidate set now or continuously or periodically and if the measured channel conditions do not meet the predetermined threshold for a predetermined time. May modify the candidate set. This may be done by discarding some antenna mappings from the current candidate set, introducing some new antenna mappings, and / or maintaining some antenna mappings. For high speed mobile applications, the candidate set may be reduced or the choice of antenna mapping may be stopped completely.

In a preferred embodiment of the present invention, the WTRU 310 may select any antenna mapping from the candidate set. The choice of antenna mapping is based on long term criteria. No channel tracking per packet is performed, so the choice of antenna mapping does not track fast changes in channels or micro-structures. Any change in antenna mapping in the candidate set may occur outside of any active transmission or reception of data packets.

Still referring to FIG. 3, during operation, the calibration unit 318 of the receiving WTRU 310 measures the selected quality metric for each of the antenna beam or beam combinations of the current candidate set, and transmits the quality metric measurement data to the beam selector. To 314. The beam selector 314 selects a preferred antenna mapping for data communication with the receiving WTRU 320 based on the quality metric measurement. Calibration unit 318 further generates observation PPDUs that respond to periodic (or aperiodic) observation requests, calibration training frames, and calibration requests as needed. The calibration unit 318 includes a processor that calculates a channel estimate matrix and a calibration matrix based on the received sounding packets, and a memory that stores the channel estimate matrices and the calibration matrices. The calibration unit 318 preferably performs signaling and message transmission and reception according to IEEE standards such as the IEEE 802.11 family of standards, more preferably the IEEE 802.11n standard.

Various quality metrics can be used to determine the desired antenna mapping. Physical layer (PHY), media access layer (MAC) or higher layer metrics are appropriate. Preferred quality metrics are channel estimation, signal to noise interference ratio (SNIR), received signal strength identifier (RSSI), short term data throughput, packet error rate, data rate, WTRU mode of operation, maximum eigen-value of the received channel estimation matrix. It includes, but is not limited to, absolute values.

To illustrate the antenna mapping selection method 200 described with reference to FIG. 2, a signal timing diagram 400 of antenna mapping selection is shown in FIG. 4. The first transmitting WTRU 410 transmits the observation PPDU 430 to the receiving WTRU 420 using antenna mapping p. The transmitting WTRU 410 then transmits a calibration training frame 432 requesting calibration. The receiving WTRU 420 is currently using antenna mapping x and responds to the CTF 432 with the observation PPDU 434 sent using the antenna mapping x. The transmitting WTRU 410 performs channel estimation 436 for each antenna mapping, i.e., antenna mapping (p) and antenna mapping (x), used by both the transmitting WTRU 410 and the receiving WTRU 420. The channel estimation matrix H (x → p) is calculated. Transmitting WTRU 410 transmits a calibration response 438 that includes the calculated channel estimate. The receiving WTRU 420 then sends its CTF 440 to the transmitting WTRU 410. The transmitting WTRU 410 responds with an observation PPDU 442. The receiving WTRU 420 computes the observation PPDU 442 to calculate 444 a calibration matrix for the channel estimate H (p → x) and the currently selected antenna mapping K (p → x), K (x → p). I use it. The receiving WTRU 420 then sends a calibration response 446 to the transmitting WTRU 410. The calibration response 446 includes a channel calibration matrix of interest for the transmitting WTRU 410, ie, K (p → x). Antenna mapping p → x is calibrated at 448.

The WTRUs are then free to initiate data packet exchange using the calibrated channel. The transmitting WTRU 410 sends a transmission request (TRQ) 450 to the receiving WTRU 420. The receiving WTRU 420 responds with the observation PPDU 452 transmitted using antenna mapping x. The transmitting WTRU 410 then calculates a steering matrix V using the calibration matrix K (x → p) 454. This results in packet data delivery 456.

The receiving WTRU 420 changes the antenna mapping from x to y for various reasons, such as a change in channel state measured using the channel quality metric, or any one WTRU movement (458). Then determine if antenna mapping p → y has been calibrated. In this embodiment, since the antenna mapping p → y has not been calibrated, calibration is necessary. The receiving WTRU 420 responds to the observation PPDU 464 using antenna mapping y. Transmitting WTRU 410 transmits observation PPDU 460 on antenna mapping p, and then transmits CTF 462. A channel estimate H (y → p) 466 is generated at the transmitting WTRU 410 and a calibration response 468 is sent including the channel estimate. The receiving WTRU 420 then requests calibration 470 and the transmitting WTRU accepts the observation PPDU 472. The receiving WTRU 420 calculates the channel estimate H (p → y) and the calibration matrix K (p → y) and K (y → p) (474). Then, a calibration response 476 is sent to the transmitting WTRU 410, including the calibration matrix of interest for the transmitting WTRU 410. At 478 the antenna mapping p → y is calibrated and the data packet exchange is ready.

The transmitting WTRU 410 requests the observation 480 and the receiving WTRU 420 responds with the transmitted observation PPDU 482 using antenna mapping y to initiate a data packet exchange. Then, the steering matrix V is calculated based on the calibration K (p → y), resulting in packet data transfer 486.

In another embodiment, the calibration of the plurality of antenna mappings occurs sequentially prior to data packet delivery. Similar to the calibration signaling of 430-448 shown in FIG. 4, the receiving WTRU may respond to the CTF using a plurality of antenna mappings selected from the current candidate set. The resulting calibration matrices can be stored for later reference. For example, the transmitting WTRU may select antenna mapping f to transmit the CTF to the receiving WTRU requiring calibration. The receiving WTRU may respond sequentially to the observation PPDU using each antenna mapping q, r, s selected from the currently available candidate set. The transmitting WTRU calibrates the channel in response to antenna mappings f-> q, f-> r, f-> s, and stores the calibration matrix in memory for later reference prior to packet data transmission. If the receiving WTRU changes its antenna mapping, e.g., antenna mapping r, the transmitting WTRU may retrieve the appropriate calibration matrix from memory and begin transmitting data packets without performing calibration again.

As an alternative, calibration of multiple antenna mappings can occur in parallel (i.e. simultaneously) to reduce signaling. In this embodiment, one observation PPDU is sent by the transmitting WTRU using a selected antenna mapping, for example, mapping b. A receiving WTRU with currently available antenna mappings t, u, v responds to a single CTF using each of the available antenna mappings t, u, v, and each antenna mapping b-> t, b-> u, b- The calibration matrix is calculated for> v. In this way, the required calibration signaling is reduced to reduce calibration delay and increase throughput.

In an alternative embodiment, when the wireless communication system conforms to the IEEE 802.x standard, the observation PPDU includes a modulation control sequence (MCS) bit field. This MCS bit field is a MAC Information Element (IE) indicating the current received WTRU antenna mapping candidate set size and the antenna mapping currently selected at the receiving WTRU. Preferably the MCS bit field is 5 bits long. Optionally, the MCS bit field contains a 1-bit 'run-length indicator' that allows the receiving WTRU to request that the receiving WTRU change the current antenna mapping candidate set.

For example, if the transmitting WTRU cannot find an antenna mapping at the receiver that satisfies its quality requirements, the transmitting WTRU may request that the receiving WTRU change the antenna mapping candidate set. In this situation, if the receiving WTRU can change its candidate set, the receiving WTRU may indicate to change its antenna mapping candidate set immediately using a new MAC management frame.

If the transmitting WTRU desires to change its candidate set for some various reasons (eg, if the transmitting WTRU cannot find an antenna mapping that meets its quality requirements from the currently available candidate set), the transmitting WTRU is MAC managed. Candidate set changes may be indicated by sending a frame to the receiving WTRU. The transmitting WTRU may then immediately change its antenna mapping candidate set and select the appropriate antenna mapping for transmission from among the mappings in the new candidate set.

In an alternate embodiment, the transmitting WTRU may request that the receiving WTRU completely disable antenna mapping. This request may be sent as a PPDU to the receiving WTRU. When receiving a PPDU with a request, the receiving WTRU may or may not respond to the request. Acceptance may be indicated by the receiving WTRU as an observation PPDU. If the receiving WTRU responds to the request, the currently selected antenna mapping at the receiving WTRU is fixed and will not change.

Referring to FIG. 5, a PPDU frame format diagram of a calibration training frame (CTF) PPDU 500 is shown in accordance with an embodiment of the present invention. Although the frame format shown in FIG. 5 follows the IEEE 802.11n standard, it should be understood that the present invention can be applied to any IEEE standard. The CTF is used to request the transmission of measurement packets from the receiving WTRU for channel calibration. The CTF PPDU 500 has a legacy short-training field (L-STF) 510, an HT-LTF 520, an HT-SIG 530, and a data field 540. The L-STF 510 has the same format as the legacy (pre-802.11n) short training field. The HT-LTF 520 is a field defined in the 802.11n PHY and is used with MIMO transmission training. The HT-SIG 530 is a field defined in 802.11n and indicates the selected modulation and coding scheme and the size of the MAC Service Data Unit (MSDU).

The MCS region 535 includes 1) an indication of the selected antenna mapping used for the transmission of the PPDU, 2) a serial or parallel request indication for the full candidate set measurement, 3) a request indication for changing the candidate set size, and 4) Repetition length bits for the update request of the antenna mapping candidate set of the receiving WTRU, 5) information related to calibration and antenna mapping selection, such as a request indication for the receiving WTRU to temporarily maintain the antenna mapping selection.

Referring to FIG. 6, an observation PPDU 600 frame format is illustrated. In addition, although the illustrated frame format follows the IEEE 802.11n standard, it should be noted that the present invention can be applied to any IEEE standard. This observation PPDU includes a legacy short-training field (L-STF) 610, a high-throughput long training field (615), a high-throughput signal field (620), and a modulation control sequence. and it includes; (MCS Modulation and Control Sequence) region 625, and this plurality of additional subsequent of _{HT-LTF (630 1 ~630 N} ), and a data area 635. The HT-SIG 620 includes two bits indicating the size of the candidate set and five bits indicating the total number of HT-LTFs 630 included in the PPDU. Thus, one HT-LTF for each antenna mapping of the candidate set may be included in the PPDU. Preferably, as described above, the size of the candidate set may be smaller than 1 and larger than 32. Each of the HT-LTFs 615, 630 in the PPDU is transmitted using a different antenna mapping selected from the candidate set. The selected antenna mapping used in the transfer of the data region 635 as well as the HT-LTF 615 is shown in the MCS region 625. The MCS region also contains: 1) HOLD / RELEASE request of successive antenna mapping selections at the receiving station, 2) HOLD / RELEASE confirmation of antenna mapping change in response to previously received HOLD / RELEASE request, and 3) pool candidate set search. And 4) additional bits to indicate acknowledgment of the request previously received in the CTF for the candidate set size change.

Referring to FIG. 7, the MAC frame format 700 of the observed PPDU data frame of FIG. 6 is illustrated. The MAC area includes a frame control area 705, a period / ID area 710, a receiver address (RA) area 715, a transmitter address (TA) area 720, a MAC service data unit (MSDU) area 725, and A frame check sequence (FCS) region 730. In an embodiment of the present invention, the MSDU area 725 has a bit indicating the HOLD / RELEASE confirmation of the antenna mapping change and the MCS area 535 in response to the received HOLD / RELEASE request as described above with reference to FIG. It includes. By reducing the candidate set, updates, calibrations and related signaling can also be reduced, increasing throughput.

Although these features and elements of the present invention have been described in the preferred embodiments of the particular combination, those skilled in the art can use each feature or element alone or without each of the features and elements of the preferred embodiments of the present invention. It will be understood that the various elements may be combined with or without the other features and elements of the present invention.

If beamforming antennas are included in the WTRU, the number of available antenna mappings can be very large. In order to optimize the communication link between two WTRUs, it is necessary to select the appropriate antenna mapping at both the transmitter and the receiver. Accordingly, a method and apparatus are provided for effectively utilizing the various antenna mappings available in a MIMO capable wireless device having a plurality of beamforming antennas.

Claims (5)

A multiple-input / multi-output (MIMO) wireless transmit / receive unit (WTRU) for selecting antenna mapping, wherein the antenna mapping is a combination of one radio frequency (RF) chain and one antenna beam. An input / multi-output wireless transmit / receive unit, A plurality of antennas comprising at least one beamforming antenna; A beam selector coupled to the plurality of antennas; A plurality of RF chains coupled to the beam selector for processing signals; A calibration unit coupled to the beam selector and configured to measure channel conditions and calibrate the channel Wherein the beam selector is configured to select antenna mapping by selectively coupling one RF chain to one antenna beam based on the measured channel condition. The method of claim 1, wherein the calibration unit, A processor configured to calculate a channel estimation matrix based on channel state measurements and to calculate a calibration matrix based on the calculated channel estimation matrix; A memory for storing the calculated channel estimation matrix and the calibration matrix A multiple-input / multi-output wireless transmit / receive unit comprising a. 3. The multiple-input / multi-output radio transceiver of claim 2, wherein the calibration unit is further configured to calibrate a plurality of antenna mappings and to store the calculated calibration matrix in the memory for later use. unit. 2. The multiple-input / multi-output wireless transmit / receive unit of claim 1, wherein the calibration unit is further configured to adjust a candidate set of available antenna mappings for selection by the WTRU based on long time channel measurements. The multi-input / multi-output wireless transmit / receive unit of claim 1, wherein the calibration unit is further configured to calculate a calibration matrix of the selected antenna mapping.

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