Performance of an OFDMA Based Multichannel Slotted ALOHA for Cognitive Radios

We present an orthogonal frequency division multiple access (OFDMA) based multichannel slotted ALOHA for cognitive radio networks (OMSA CR) The performance of an infinite population based OMSA CR system is analyzed in terms of channel capacity throughput delay and packet capture effect We investigate the channel capacity for OMSA CR with perfect or imperfect spectrum sensing We introduce the proposed CR MAC based on two channel selection schemes non agile channel selection (NCS) and agile channel selection (ACS) Comparing them we show the tradeoff between complexity and system performance We verify the proposed CR system model using numerical analysis In particular using simulation with a finite populated linear feedback model we observe the OMSA CR MAC tradeoff between throughput and minimum delay whose results matched those of the analytical framework Numerical results for the proposed system throughput are also compared to conventional MACs including pure ALOHA based CR MAC