On the impact of the primary network activity on the achievable capacity of spectrum sharing over fading channels

Abstract

Abstract-When utilizing spectrum sharing in wireless channels, a secondary service may access the spectrum allocated to the primary service while this frequency band is under-utilized. The availability of the frequency band to the secondary user is a function of the activity of the users in the primary network. In this paper, we analyze the achievable capacity of the secondary service which employs opportunistic spectrum Access (OSA) over a fading environment based on the primary network activity. We categorized OSA methods into Access Limited OSA (AL-OSA), and Interference Limited OSA (IL-OSA) schemes. In AL-OSA the spectrum is shared with the secondary service in circumstances in which the primary service is totally inactive however, in IL-OSA access to the spectrum is allowed subject to an interference threshold. For both cases we develop analytical frameworks to analyze the impact of the primary network activity on the achievable capacity of the secondary service. Simulation results confirm our analysis and also show that in cases where higher activity is in the primary network, IL-OSA is the more appropriate OSA method. For a less active primary network, AL-OSA is shown to performs better with respect to the achievable capacity.Index Terms-DS-CDMA networks, OFDM, opportunistic spectrum access, spectrum sharing.

Interference Management in Underlay Spectrum Sharing Using Indirect Power Control Signalling

“…The more activity in the primary network, the higher the value of total interference is. Using the results presented in our previous works ( [5], [22]), K can be obtained for the uplink of a DS-CDMA network with chip rate W , providing S services each with n s users and activity factor ν s , required bit-energy to interference plus noise spectral density, ρ s , and bit-rate R s as (see Appendix I)…”

“…To satisfy the interference threshold constraint, in underlay spectrum sharing, Channel State Information (CSI) between the secondary transmitter and receiver (secondary-channel), and between the primary receiver and the secondary transmitter (cross-channel) are required (see, e.g., [4], [5], [6]). …”

Outage Performance of the Primary Service in Spectrum Sharing Networks

“…Therefore, the aggregate interference imposed by the SS transmissions must be kept below Q. Consequently, as far as the secondary network satisfies the interference threshold, i.e., I Q, the spectrum is accessible [23] and [31]. Using such terminology P p int ¼ Á PfI > Qg namely interference probability can be considered as a performance metric that indicates the impact of the secondary activity on the primary performance [25].…”

Achievable Capacity in Hybrid DS-CDMA/OFDM Spectrum-Sharing

“…Therefore, the average interference in the receiver of the secondary service user in each subchannel is ðK À 1ÞN 0 B c ; K ! 1, where K is a system parameter related to the primary network characteristics [5].…”

“…Therefore, DS-CDMA/OFDM combination provides a new degree of freedom by enabling the secondary service to adaptively select appropriate subchannels for spectrum sharing. The benefits of this combination regarding to the maximum achievable capacity and its implementation are also studied in our previous works [4], [5], [6].…”