Dynamic Spectrum Allocation Based On Cognitive User QoS And Channel Characteristics

The emerging wireless communication flourishes and the spectrum resource is very precious. But limited by the active spectrum management, the utilization rate of the spectrum is low. Cognitive radio is a technology that it can improve the utilization of the licensed spectrum. The dynamic spectrum allocation (DSA) is a key technology of the cognitive radio. This paper proposed two algorithms on the sides of the bandwidth efficiency cognitive user getting, the channel utilization, the QoS of the cognitive user and the reliability of the cognitive users transmitting data.The paper proposes an algorithm named dynamic spectrum allocation based on the Kuhn-Munkres algorithm to guarantee cognitive users’QoS. The purpose of the algorithm is to optimize the bandwidth efficiency and the channel utilization. It also can get better QoS in terms of the waiting time for the cognitive users to take up the channels. First, assign priorities for the cognitive users and channel. Then set cognitive users with different priorities use channels with different priorities. At last, use the Kuhn-Munkres algorithm to match the cognitive users and idle channels. The experiment results show that the proposed algorithm can close to the greedy algorithm in the bandwidth efficiency. When the number of the cognitive users equals to the channels, the channel utilization will close to1in this algorithm. It also can shorten the waiting time for the cognitive users to take up the channels.In the process for the cognitive users using a channel to send data, the primary users may cut to use authorized channels suddenly. Because the primary users have the priority to use the authorized channels and use them randomness. Cognitive users in the process of data transmission could be interrupted at any time and their rights cannot be guaranteed.First, do a statistical about the free duration of the channels. Estimate the time of the cognitive users to occupy the channel sending data. Then compare:If a cognitive user is expected to take up a channel shorter than or equal to the authorized channel minimum free duration, then we use the Kuhn-Munkres algorithm to allocate the channels to the cognitive user. If a cognitive user is expected to take up a channel longer than authorized channel’s minimum free time or the cognitive user is interrupted by the primary user during the transmitting, then we need to assign a new channel for the cognitive user. The new channel based on the average free time, the idle probability and the bandwidth efficiency the cognitive user can get three factors. In the premise of guaranteeing the reliability of the transmitting data, the proposed algorithm maximizes the bandwidth efficiency of the cognitive users.