System and Method for Random Access Backoffs

Abstract

A method of performing a random access procedure includes randomly selecting a backoff time from within a backoff window ranging from 0 to a specified multiple of a random access preamble unit, waiting until a time initialized with the backoff time expires, and retransmitting a random access preamble.

What is claimed is: 
     
         1 . A method for performing a random access procedure, the method comprises:
 randomly selecting, by a user equipment (UE), a backoff time from within a backoff window ranging from 0 to a specified multiple of a random access preamble unit;   waiting, by the UE, until a time initialized with the backoff time expires; and   retransmitting, by the UE, a random access preamble.   
     
     
         2 . The method of  claim 1 , wherein the specified multiple is one of a plurality of specified multiples, and wherein different specified multiples are selected for random access preambles with different durations. 
     
     
         3 . The method of  claim 1 , wherein there is a plurality of sets of specified multiples, and wherein the specified multiple is selected from one of the plurality of sets of specified multiples in accordance with a duration of the random access preamble. 
     
     
         4 . The method of  claim 1 , wherein the random access preamble is initially transmitted on one of a first carrier or a first band, and wherein the random access preamble is retransmitted on one of a second carrier or a second band. 
     
     
         5 . The method of  claim 1 , wherein randomly selecting the backoff time comprises:
 selecting an initial backoff time within a step of a predefined period; and   selecting the backoff time within the initial backoff time.   
     
     
         6 . The method of  claim 1 , further comprising segmenting the random access preamble into a plurality of blocks, wherein retransmitting the random access preamble comprises separately transmitting each of the plurality of blocks. 
     
     
         7 . The method of  claim 6 , wherein separately transmitting each of the plurality of blocks comprises interleaving at least some of the plurality of blocks with an uplink data channel. 
     
     
         8 . The method of  claim 1 , wherein the random access preamble is transmitted in a network resource, and wherein the network resource also comprises a gap inserted after the network resource so that a duration of the network resource and a gap time associated with the gap is equal to an integer multiple of a subframe duration. 
     
     
         9 . A method for performing a random access procedure, the method comprises:
 determining, by an evolved NodeB (eNB), a backoff parameter value in accordance with a random access preamble unit associated with a user equipment (UE) participating in the random access procedure;   signaling, by the eNB, an indicator of the backoff parameter value; and   receiving, by the eNB, a random access preamble in accordance with the backoff parameter value.   
     
     
         10 . The method of  claim 9 , wherein the backoff parameter value specifies a multiple of the random access preamble unit. 
     
     
         11 . The method of  claim 10 , wherein there is a plurality of sets of specified multiples, and wherein the specified multiple is selected from one of the plurality of sets of specified multiples in accordance with a duration of the random access preamble. 
     
     
         12 . The method of  claim 9 , further comprising:
 selecting a step of a predefined period; and   signaling an indicator of the step of the predefined period.   
     
     
         13 . The method of  claim 9 , wherein the random access preamble is segmented into a plurality of blocks, and wherein receiving the random access preamble comprises separately receiving each of the plurality of blocks. 
     
     
         14 . The method of  claim 13 , further comprising receiving an uplink data channel interleaved with at least some of the plurality of blocks. 
     
     
         15 . A method for transmitting a random access preamble, the method comprising:
 generating, by a user equipment (UE), the random access preamble; and   when a number of physical random access channel (PRACH) repetitions per attempt is larger than a threshold,   segmenting, by the UE, the random access preamble into a plurality of blocks, and   separately transmitting, by the UE, each of the plurality of blocks.   
     
     
         16 . The method of  claim 15 , wherein separately transmitting each of the plurality of blocks comprises interleaving at least some of the plurality of blocks with an uplink data channel. 
     
     
         17 . A non-transitory computer-readable medium storing programming for execution by at least one processor, the programming including instructions to:
 randomly select a backoff time from within a backoff window ranging from 0 to a specified multiple of a random access preamble unit;   wait until a time initialized with the backoff time expires; and   retransmit a random access preamble.   
     
     
         18 . The non-transitory computer-readable medium of  claim 17 , wherein the specified multiple is one of a plurality of specified multiples, and wherein the programming includes instructions to select different specified multiples for random access preambles of different durations. 
     
     
         19 . The non-transitory computer-readable medium of  claim 17 , wherein there is a plurality of sets of specified multiples, and wherein the programming includes instructions to select the specified multiple from one of the plurality of sets of specified multiples in accordance with a duration of the random access preamble. 
     
     
         20 . The non-transitory computer-readable medium of  claim 17 , wherein the programming includes instructions to select an initial backoff time within a step of a predefined period, and select the backoff time within the initial backoff time. 
     
     
         21 . The non-transitory computer-readable medium of  claim 17 , wherein the programming includes instructions to segment the random access preamble into a plurality of blocks, and separately transmit each of the plurality of blocks.