Spectrum efficiency optimization in multiuser Ultra Wideband cognitive radio networks

Abstract

In this paper, we present a new dynamic spectrum access algorithm in multiuser Ultra Wideband cognitive radio networks for spectrum efficiency optimization. The proposed optimization algorithm can optimally distribute the radio spectrum, transmitted power and data bits among different UWB nodes while guaranteeing the aggregate interference power to the primary wireless systems is below a certain threshold. The aggregate interference power in the UWB fading channel environment is computed by using Fenton-Wilkinson method. We analyze the performance of the proposed algorithm over different UWB channel models. The results illustrate that the new dynamic spectrum access algorithm can maximize the spectrum efficiency with a low complexity.

Joint Spectrum Sensing and Power Allocation Algorithm for Spectrum Efficiency Optimization in Ultra Wideband Cognitive Radio Networks

“…For power allocation, a greedy algorithm based method can be applied to assign bits to the subcarrier with the lowest cost [22]. The algorithm complexity in [22] is proportional to O(β · B total N used log 2 N used ), where N used is the number of the used subcarriers, and β is a ratio.…”

“…The algorithm complexity in [22] is proportional to O(β · B total N used log 2 N used ), where N used is the number of the used subcarriers, and β is a ratio. Since N used contributes to the complexity of the spectrum efficiency maximization algorithm, a new group power allocation algorithm is proposed based on the previous algorithm proposed in [22] to lower the computational complexity.…”

“…The group power allocation algorithm consists of three steps, they are: 1) Grouping a number of adjacent subcarriers into subcarrier groups, next 2) Allocating power on subcarrier groups by the algorithm proposed in [22], then 3) Allocating bits on the subcarriers in each subcarrier group by equal power allocation. The coherence bandwidth for each UWB CM are: 53.6 MHz, 28.9 MHz, 20.6 MHz and 12.4 MHz for CM1, CM2, CM3 and CM4, respectively [23].…”

“…Then, the cost of assigning a number of bits to the subcarrier group can be derived as (13) and (14), and the optimal power allocation algorithm proposed in [22] can be applied. Compared with the power allocation algorithm in [22], the orderof-growth of the proposed spectrum management algorithm for the joint algorithm is reduced to O(β ·B total N g log 2 N g ).…”

“…Then, the cost of assigning a number of bits to the subcarrier group can be derived as (13) and (14), and the optimal power allocation algorithm proposed in [22] can be applied. Compared with the power allocation algorithm in [22], the orderof-growth of the proposed spectrum management algorithm for the joint algorithm is reduced to O(β ·B total N g log 2 N g ). Since the complexity of the two algorithms both take linearithmic time, the reduction of the term N in N · log 2 N will significantly lower the complexity of the algorithm when the total number of the allocated bits B total is the same in the two algorithms.…”