Channel access and fairness protocol for contention-based-access networks with biased detection
A channel access protocol method to impart bandwidth fairness while maximizing throughput in a class of contention-based-access (CBA) TDMA networks that has no carrier sense capability, and that experiences biased detection at the receiver (base station) by virtue of physical layer detection algorithms is disclosed.
1. A channel access protocol method that maximizes network throughput while maintaining bandwidth fairness for a class of Contention-Based-Access (CBA) networks that has m, where m is a non-zero positive integer value, CBA slots for CBA bursts in a Media Access Control (MAC) super-frame comprising:
first a base station broadcasting in each super-frame a request message with a control field wherein if said control field is toggled to a non-zero positive integer value indicating the number of active requests said request message is interpreted as a bandwidth request CBA packet drop due to collision in CBA slot 1 by mobile terminals that are contending for channel access in CBA slot 1 and by, at-most, (m−1) non-contending mobile terminals that are transmitting in each of the CBA slots k, where k∈[2, 3, . . . , m] for a MAC super-frame with m CBA slots;
then, whenever said request message is interpreted as bandwidth request CBA packet drop due to collision in CBA slot 1 by the mobile terminals that are contending for channel access in CBA slot 1 in the current super-frame, the non-zero positive integer value control field indicating the number of active requests notifies said mobile terminals to retransmit bandwidth request CBA packet in CBA slot 1 in the subsequent super-frame;
then, whenever said request message is interpreted as bandwidth request CBA packet drop due to collision in CBA slot 1 by the at-most (m−1) non-contending mobile terminals that are transmitting in each of the CBA slots k, where k∈[2, 3, . . . , m] for a MAC super-frame with m CBA slots, in the current super-frame, the non-zero positive integer value control field indicating the number of active requests notifies each of said mobile terminals that is transmitting in CBA slot k to move to CBA slot (k+1) if k<m or move to a wait state if k=m in the subsequent super-frame;
said wait state having a wait state window size that is set to non-zero positive integer value control field indicating the number of active requests×wait state factor wherein said wait state factor can be assigned a non-zero positive integer value;
whenever said request message is interpreted as bandwidth request CBA packet drop due to collision in CBA slot 1 by a mobile terminal that is transmitting in CBA slot m, a local counter in the said mobile terminal is set to zero, and the said local counter is incremented every super-frame in the subsequent super-frames until the said local counter value is equal to the said non-zero positive integer value control field indicating the number of active requests×wait state factor;
whenever a mobile terminal in said wait state has said local counter value equal to said non-zero positive integer value control field indicating the number of active requests×wait state factor, said mobile terminal starts contending in CBA slot 1 in the subsequent super-frame if said mobile terminal's internal queue value is greater than zero; and,
whenever a mobile terminal that is transmitting in CBA slot k, where k∈[1, 2, 3, . . . , m] for a MAC super-frame with m CBA slots, and said internal queue value of the said mobile terminal is equal to zero, said mobile terminal moves to an idle state after a static time-out interval.