Strategy of Dynamic Spectrum Access Based-on Spectrum Pool

Under static frequency allotment scheme, each licensed operator is allocated a frequency band in which its user can transmit, but the spectrum may not be fully utilized either on geographical or at temporal level. On the other hand, on some hot spot business frequency bands, spectrum resources become in short supply. Dynamic spectrum access (DSA) technology based on cognitive radio is an effective measure to improve the spectrum utility efficiency. It can increase spectrum income for spectrum holder, and provide a variety of services to users. Many papers discussed the technology of dynamic spectrum access and sharing based on cognitive radio. However, few reaches to the field of system performances evaluation based on spectrum pool strategy. In this paper, we propose two DSA strategies: one based on instant access manner, and the other based on spectrum pool access manner. Both theoretical and simulation results indicate that the DSA strategy based on spectrum pool has obvious advantages. Optimal capacity and update time of spectrum pool are all studied. It is found that there is quantitative mathematical relationship between the optimal capacity of spectrum pool and system efficiency. Update time of spectrum pool varies according to spectrum characteristics and user's quality of service (QoS) demands. There are different update strategies in licensed and unlicensed frequency bands. Under the assumed conditions, the update interval varies within one hour in most cases.