Yinghua Zhang^1,2, Yanfang Dong², Lei Wang¹, Jian Liu^1,*, Yunfeng Peng¹, Jim Feng³

CMC-Computers, Materials & Continua, Vol.60, No.1, pp. 379-393, 2019, DOI:10.32604/cmc.2019.05790

Abstract In this paper, we propose a downlink cognitive non-orthogonal multiple access (NOMA) network, where the secondary users (SUs) operate in underlay mode. In the network, secondary transmitter employs NOMA signaling for downlink transmission, and the primary user (PU) is interfered by the transmission from SU. The expressions for the outage probabilities are derived in closed-form for both primary and secondary users in the presence of channel estimation error. Numerical simulation results show that the channel estimation error and the inter-network interference cause degradation of the downlink outage performance. Also the power allocation and the location have a significant impact on… More >

Yueyue Li^1,*, Zhong Huang¹, Yugang Ma², Guangjun Wen¹

CMC-Computers, Materials & Continua, Vol.56, No.1, pp. 35-46, 2018, DOI: 10.3970/cmc.2018.03712

Abstract As a fundamental operation in ad hoc networks, broadcast could achieve efficient message propagations. Particularl y in the cognitive radio ad hoc network where unlicensed users have different sets of available channels, broadcasts are carried out on multiple channels. Accordingly, channel selection and collision avoidance are challenging issues to balance the efficiency against the reliability of broadcasting. In this paper, an anti-collision selective broadcast protocol, called acSB, is proposed. A channel selection algorithm based on limited neighbor information is considered to maximize success rates of transmissions once the sender and receiver have the same channel. Moreover, an anti-collision scheme is… More >