Sensing-based Optimal Power Allocation Strategy In Cognitive Radio Network

Recently, as the wireless communication technology has an increasingdevelopment, spectrum scarcity problems stand out increasingly. As a new smartwireless communication technology, CR can sense wireless environment around it,and adaptively determines its transmission parameters, it aims for efficient spectrumusage by allowing CR users to access licensed frequency bands under the condition ofprotecting the primary user from harmful interference, also, it can improve thethroughput of CR network. so, it becomes more and more popular. By using CRtechnology, how to allocate power for CR users can not only maximize CR users’profit, but also, protect the primary user from harmful interference, It graduallybecomes one of the hot research areasConsidering the above situation, the mainly contents of the paper are as follows：First, taking full account of the primary user’ s departure or arrival in the processof a frame interval, the paper proposes a new power allocation strategy—four statuspower allocation strategy. The effect of primary user traffic on the sensing-throughputtradeoff for cognitive radio network is studied and is compared with the traditionalmodel. In traditional model the primary user has a constant occupancy state duringthe entire frame duration.In other words, they assume that the primary user is eitheractive or inactive for the whole secondary frame period. In reality, the primary usermay start or stop occupying the licensed channel at any time, especially when theprimary user has a high traffic rate or when a long secondary frame interval is used.Based on the above situation，in sensing-based model，to maximizes the throughput ofcognitive radio networks it views achievable throughput as the objective function,puts forward four status of cognitive users in the process of secondary frame period,and gives the four status different power respectively. Results show that thethroughput of secondary network in new model is influenced by the primary usertraffic intensity, when primary user has a high traffic intensity, the new model isbetter than the traditional model in improving achievable throughput. Finally, a heuristic relationship among the optimal sensing time, achievable throughput and theSNR of the primary user is given.Second. Considering the mobile terminal of the battery capacity is limited in thewireless communication system, and now the battery technology cannot meet thevigorous growth of power consumption. In order to improve power utilization ofcognitive radio networks, and to avoid the waste of power, in this paper, a newperformance metric: effective throughput profits was proposed. In sensing-basedmodel, it takes effective throughput as the objective function, designs thetransmission policy of cognitive users, and also studies how to choose thetransmission policy in different environment. Based on this standard, the cognitiveuser take full advantage of its sensing results and sensing accuracy, adaptivelydetermines its transmission strategy, through joint rate and power allocations tomaximize its effective throughput. Our results validate the advantages of our newperformance metric in improving power utilization of cognitive radio networks andeffectively relieves the waste of power in the process of information transmission.