Method and apparatus for communicating with extended range in a wireless network

Abstract

Techniques for supporting communication over an extended range in a wireless network are disclosed. In one aspect, a station sends multiple messages of a given type for different operating modes. These messages can be detected by stations with different capabilities, which may avoid collisions between stations. In one design, a first station receives a Request-to-Send (RTS) message from a second station having data to send. The first station sends a first Clear-to-Send (CTS) message and also a second CTS message in response to the RTS message. The second CTS message has an extended range as compared to the first CTS message. The first station thereafter (i) receives data sent by the second station in response to the second CTS message and (ii) sends an acknowledgement having an extended range.

What is claimed is: 
     
         1 . A method for wireless communication, comprising:
 making energy measurements of a wireless medium during a backoff procedure, each energy measurement being made over a measurement period covering multiple time slots; and   determining whether the wireless medium is clear or busy in each measurement period during the backoff procedure based on an energy measurement for the measurement period.   
     
     
         2 . The method of  claim 1 , further comprising:
 determine whether to continue or suspend the backoff procedure in each measurement period based on a determination of whether the wireless medium is clear of busy during the measurement period.   
     
     
         3 . The method of  claim 1 , further comprising:
 detecting the wireless medium to be busy in a measurement period;   suspending the backoff procedure in response to detecting the wireless medium to be busy in the measurement period; and   resuming the backoff procedure after detecting the wireless medium to be clear for an extended distributed coordination function (DCF) interframe space (DIFS), the extended DIFS being for an extended range mode and being longer than a DIFS for a non-extended range mode.   
     
     
         4 . The method of  claim 1 , further comprising:
 determining the wireless medium to be clear for an extended distributed coordination function (DCF) interframe space (DIFS) prior to performing the backoff procedure, the extended DIFS being for an extended range mode and being longer than a DIFS for a non-extended range mode.   
     
     
         5 . The method of  claim 3 , wherein the extended DIFS has a duration determined based on a length of a preamble of a message in the extended range mode. 
     
     
         6 . The method of  claim 1 , further comprising:
 detecting a message transmitted via the wireless medium; and   waiting for the wireless medium to be clear for an extended interframe space (EIFS) for an extended range mode prior to performing the backoff procedure, the EIFS for the extended range mode being longer than an EIFS for a non-extended range mode.   
     
     
         7 . An apparatus for wireless communication, comprising:
 at least one processor configured to:
 make energy measurements of a wireless medium during a backoff procedure, each energy measurement being made over a measurement period covering multiple time slots; and 
 determine whether the wireless medium is clear or busy in each measurement period during the backoff procedure based on an energy measurement for the measurement period. 
   
     
     
         8 . The apparatus of  claim 7 , wherein the at least one processor is configured to determine whether to continue or suspend the backoff procedure in each measurement period based on a determination of whether the wireless medium is clear of busy during the measurement period. 
     
     
         9 . The apparatus of  claim 7 , wherein the at least one processor is configured to:
 detect the wireless medium to be busy in a measurement period;   suspend the backoff procedure in response to detecting the wireless medium to be busy in the measurement period; and   resume the backoff procedure after detecting the wireless medium to be clear for an extended distributed coordination function (DCF) interframe space (DIFS), the extended DIFS being for an extended range mode and being longer than a DIFS for a non-extended range mode.   
     
     
         10 . The apparatus of  claim 7 , wherein the at least one processor is configured to determine the wireless medium to be clear for an extended distributed coordination function (DCF) interframe space (DIFS) prior to performing the backoff procedure, the extended DIFS being for an extended range mode and being longer than a DIFS for a non-extended range mode. 
     
     
         11 . The apparatus of  claim 9 , wherein the extended DIFS has a duration determined based on a length of a preamble of a message in the extended range mode. 
     
     
         12 . The apparatus of  claim 7 , wherein the at least one processor is configured to:
 detect a message transmitted via the wireless medium; and   wait for the wireless medium to be clear for an extended interframe space (EIFS) for an extended range mode prior to performing the backoff procedure, the EIFS for the extended range mode being longer than an EIFS for a non-extended range mode.