From: Multichannel MAC protocol with dynamic backoff contention for distributed cognitive radio networks
Symbol | Explanations |
---|---|
N | Number of SUs in the DCRN |
N _{st} | Number of successful transmission pairs in a MAC cycle |
M | Total number of licensed data channels |
M _{ic} | Number of idle licensed channels |
M _{sic} | Number of remaining sensed idle licensed channels |
K | Largest number of slots for the contention phase |
w _{ i} | Average number of winning slots (successful SUs) in the ith backoff |
contention window | |
W | Number of slots won in the whole contention phase |
Q | Parameter which is broadcasted on the update slot to indicate the |
number of contention slots of the next backoff window | |
Q _{1} | Number of contention slots in the first backoff window |
Q _{ i} | Number of contention slots in the ith (i>1) backoff window |
Q _{c} | Number of contention slots in the whole contention phase |
P _{d} | Each SU’s local detection probability |
P _{f} | Each SU’s local false alarm probability |
P _{s} | Probability of a successful RTS contention in the initial backoff window |
P _{T} | Probability of a successful data transmission in a MAC cycle |
P _{NT} | Probability of fail to transmit data in a MAC cycle |
D | Average channel access delay in terms of MAC cycles |
T _{cycle} | Time duration of a MAC frame cycle |
T _{c} | Time duration of contention phase |
T _{ct} | Time duration of contention phase and transmission phase |
T _{tr} | Time duration of data transmission phase |
α | Average utilization probability for all the licensed channels |
σ | Duration of a contention slot in contention phase |
R | Fixed rate for each data channel |
n _{1} | Number of remaining SUs (which still need contention) in Algorithm 1 |
n _{2} | Number of remaining contention slots in Algorithm 1 |