Pre-allocated random access identifiers
Systems and methods of pre-allocating identifiers to wireless devices for use in requesting resources over a random access channel are described. A wireless communication system includes a random access channel over which wireless devices can anonymously send requests for resources. The base stations receiving and processing the anonymous requests reduces the probability of random access channel collisions and conserves the resources needed to support the anonymous requests by pre-allocating one or more identifiers to select wireless devices. The wireless devices having the pre-allocated codes can transmit a particular code over the random access channel as a request for resources that uniquely identifies the requester.
1 . A method of operating a feedback processor in an orthogonal frequency division OFDM system, comprising:
monitoring timing of a received signal from a subscriber station on a random access channel, the received signal comprising an assigned single access identifier uniquely identifying the subscriber station to the feedback processor, the single access identifier assigned, via dedicated signaling, from a subset of access identifiers designated, by the feedback processor, as allocatable access identifiers from a set of access identifiers, the random access channel usable by subscriber stations for transmission without a prior allocation of resources of the random access channel; and
generating a feedback control signal, based on the monitored timing of the received signal, to instruct the subscriber station to advance or delay a transmission time, in order to better align a timing of the subscriber station with a system timing.
2 . The method of claim 1 , further comprising:
generating a signal for transmission to one or more subscriber stations including an indication of the subset of access identifiers designated, by the feedback processor, as allocatable access identifiers.
3 . The method of claim 1 , further comprising:
generating a signal for transmission to the subscriber station including an indication of the assigned single access identifier uniquely identifying the subscriber station to the feedback processor.
4 . The method of claim 1 , further comprising:
receiving from the subscriber station an indication that the subscriber station supports use of an assigned single access identifier uniquely identifying the subscriber station to the feedback processor.
5 . The method of claim 1 , wherein the single access identifier uniquely identifying the subscriber station is a code.
6 . The method of claim 1 , wherein the single access identifier uniquely identifying the subscriber station is associated with a usage type.
7 . The method of claim 6 , wherein the usage type is initial ranging, periodic ranging, bandwidth request, or handover.
8 . The method of claim 1 , wherein the assigned single access identifier uniquely identifying the subscriber station is assigned by:
determining a handover condition for the subscriber station; and
assigning the single access identifier uniquely identifying the subscriber station based on the handover condition.
9 . The method of claim 1 , wherein the assigned single access identifier uniquely identifying the subscriber station avoids a collision probability associated with subscriber station selected access identifiers, and the assigned single access identifier uniquely identifying the subscriber station avoids a collision probability associated with other access identifiers in the subset of access identifiers.
10 . A base station comprising:
a receiver operable to receive a signal from a subscriber station on a random access channel, the received signal comprising an assigned single access identifier uniquely identifying the subscriber station to the base station, the single access identifier assigned, via dedicated signaling, from a subset of access identifiers designated, by the base station, as allocatable access identifiers from a set of access identifiers, the random access channel usable by subscriber stations for transmission without a prior allocation of resources of the random access channel;
a baseband orthogonal frequency division multiplex (OFDM) processor operable to:
monitor timing of the received signal from the subscriber station; and
generate a feedback control signal, based on the monitored timing of the received signal, to instruct the subscriber station to advance or delay a transmission time, in order to better align a timing of the subscriber station with a system timing; and
a transmitter operable to transmit the feedback control signal to the subscriber station.
11 . The base station of claim 10 , wherein the baseband OFDM processor is further operable to generate a signal for transmission to one or more subscriber stations including an indication of the subset of access identifiers designated, by the base station, as allocatable access identifiers.
12 . The base station of claim 10 , wherein the baseband OFDM processor is further operable to generate a signal for transmission to the subscriber station including an indication of the assigned single access identifier uniquely identifying the subscriber station to the base station.
13 . The base station of claim 10 , wherein the receiver is further operable to receive from the subscriber station an indication that the subscriber station supports use of an assigned single access identifier uniquely identifying the subscriber station to the base station.
14 . The base station of claim 10 , wherein the single access identifier uniquely identifying the subscriber station is a code.
15 . The base station of claim 10 , wherein the single access identifier uniquely identifying the subscriber station is associated with a usage type.
16 . The base station of claim 15 , wherein the usage type is initial ranging, periodic ranging, bandwidth request, or handover.
17 . The base station of claim 10 , wherein the baseband OFDM processor is operable to assign the assigned single access identifier uniquely identifying the subscriber station by:
determining a handover condition for the subscriber station; and
assigning the single access identifier uniquely identifying the subscriber station based on the handover condition.
18 . The base station of claim 10 , wherein the assigned single access identifier uniquely identifying the subscriber station avoids a collision probability associated with subscriber station selected access identifiers, and the assigned single access identifier uniquely identifying the subscriber station avoids a collision probability associated with other access identifiers in the subset of access identifiers.