Methods and apparatus for mimo transmission

Abstract

Methods for multiple input-multiple output (MIMO) transmission are provided herein. A method may include sensing, using at least one of a plurality of antenna chains, radio frequency (RF) energy on a channel in a first time duration and may indicate the channel is busy. RF energy may be sensed on the channel using the at least one of the plurality of antenna chains in a second time duration and may indicate the channel is not busy. A method may include sending energy level sensed during the second time duration, a frame using the at least one of the plurality of antenna chains. The frame may indicate timing information associated with a MIMO transmission. The MIMO transmission may be sent using the indicated timing information and the at least one of the plurality of antenna chains.

What is claimed is: 
     
         1 . A station (STA), the STA comprising:
 a processor; and   a transceiver;   the processor and the transceiver configured to sense, using at least one of a plurality of antenna chains, radio frequency (RF) energy on a channel in a first time duration, wherein the level of RF energy sensed during the first time duration indicates that the channel is busy;   the processor and the transceiver configured to sense, using the at least one of the plurality of antenna chains, RF energy on the channel in a second time duration, wherein the level of RF energy sensed during the second time duration indicates that the channel is not busy;   the processor and the transceiver configured to, based on the energy level sensed during the second time duration, send a frame using the at least one of the plurality of antenna chains, wherein the frame indicates timing information associated with a multiple input-multiple output (MIMO) transmission to be sent by the STA; and   the transceiver configured to send the MIMO transmission on the channel using the indicated timing information and the at least one of the plurality of antenna chains.   
     
     
         2 . The STA of  claim 1 , wherein the frame is a request-to-send (RTS) frame. 
     
     
         3 . The STA of  claim 2 , the processor and the transceiver configured to receive, in response to the RTS frame, at least one clear-to-send (CTS) frame, wherein the MIMO transmission is sent at least an interframe space after the at least one received CTS frame. 
     
     
         4 . The STA of  claim 3 , wherein the MIMO transmission is a single-user (SU) MIMO transmission, and wherein the at least one CTS frame is received using beamforming parameters associated with beamforming parameters used to transmit the RTS frame. 
     
     
         5 . The STA of  claim 3 , wherein the MIMO transmission is a multi-user (MU) MIMO transmission and wherein the CTS frame is a CTS-to-self frame. 
     
     
         6 . The STA of  claim 1 , the processor and the transceiver configured to detect signals on the channel in the first time duration and in the second time duration, wherein a signal strength of at least one signal detected in the first time duration indicates that the channel is busy, and wherein a signal strength of at least one signal detected in the second time duration indicates that the channel is not busy. 
     
     
         7 . The STA of  claim 1 , wherein the MIMO transmission includes at least one field for use in a beamforming training procedure. 
     
     
         8 . The STA of  claim 7 , configured as an initiating STA of the beamforming training procedure. 
     
     
         9 . The STA of  claim 8 , the processor and the transceiver configured to receive, in response to the MIMO transmission, channel feedback associated with the at least one field from a responding STA of the beamforming training procedure. 
     
     
         10 . The STA of  claim 7 , wherein the at least one field is a training (TRN) field. 
     
     
         11 . A method performed by a station (STA), the method comprising:
 sensing, using at least one of a plurality of antenna chains, radio frequency (RF) energy on a channel in a first time duration, wherein the level of RF energy sensed during the first time duration indicates that the channel is busy;   sensing, using the at least one of the plurality of antenna chains, RF energy on the channel in a second time duration, wherein the level of RF energy sensed during the second time duration indicates that the channel is not busy;   sending, based on the energy sensed during the second time duration, a frame using the at least one of the plurality of antenna chains, wherein the frame indicates timing information associated with a multiple input-multiple output (MIMO) transmission to be sent by the STA; and   sending the MIMO transmission on the channel using the indicated timing information and the at least one of the plurality of antenna chains.   
     
     
         12 . The method of  claim 11 , wherein the frame is a request-to-send (RTS) frame. 
     
     
         13 . The method of  claim 12  comprising receiving, in response to the RTS frame, at least one clear-to-send (CTS) frame, wherein the MIMO transmission is sent at least an interframe space after the at least one received CTS frame. 
     
     
         14 . The method of  claim 13 , wherein the MIMO transmission is a single-user (SU) MIMO transmission, and wherein the at least one CTS frame is received using beamforming parameters associated with beamforming parameters used to transmit the RTS frame. 
     
     
         15 . The method of  claim 13 , wherein the MIMO transmission is a multi-user (MU) MIMO transmission and wherein the CTS frame is a CTS-to-self frame. 
     
     
         16 . The method of  claim 11  comprising detecting signals on the channel in the first time duration and in the second time duration, wherein a signal strength of at least one signal detected in the first time duration indicates that the channel is busy, and wherein a signal strength of at least one signal detected in the second time duration indicates that the channel is not busy. 
     
     
         17 . The method of  claim 11 , wherein the MIMO transmission includes at least one field for use in a beamforming training procedure. 
     
     
         18 . The method of  claim 7 , wherein the STA is configured as an initiating STA of the beamforming training procedure. 
     
     
         19 . The method of  claim 18  comprising receiving, in response to the MIMO transmission, channel feedback associated with the at least one field from a responding STA of the beamforming training procedure. 
     
     
         20 . The method of  claim 17 , wherein the at least one field is a training (TRN) field.