Analysis Framework for Opportunistic Spectrum OFDMA and its Application to the IEEE 802.22 Standard

TL;DR

This paper develops an analytical model for evaluating the throughput of Opportunistic Spectrum OFDMA networks, considering various strategies and their impact on IEEE 802.22 standard performance, especially under different spectrum sensing and user activity scenarios.

Contribution

It introduces a discrete-time Markov chain model that assesses the effects of different channel allocation and spectrum sensing strategies on OS-OFDMA throughput, specifically for IEEE 802.22.

Findings

OS-OFDMA with subchannel notching and channel bonding achieves nearly ten times higher throughput.

IEEE 802.22 can support QoS classes with moderate wireless microphone activity.

Two-stage spectrum sensing improves throughput when sensing durations are optimized.

Abstract

We present an analytical model that enables throughput evaluation of Opportunistic Spectrum Orthogonal Frequency Division Multiple Access (OS-OFDMA) networks. The core feature of the model, based on a discrete time Markov chain, is the consideration of different channel and subchannel allocation strategies under different Primary and Secondary user types, traffic and priority levels. The analytical model also assesses the impact of different spectrum sensing strategies on the throughput of OS-OFDMA network. The analysis applies to the IEEE 802.22 standard, to evaluate the impact of two-stage spectrum sensing strategy and varying temporal activity of wireless microphones on the IEEE 802.22 throughput. Our study suggests that OS-OFDMA with subchannel notching and channel bonding could provide almost ten times higher throughput compared with the design without those options, when the activity and density of wireless microphones is very high. Furthermore, we confirm that OS-OFDMA implementation without subchannel notching, used in the IEEE 802.22, is able to support real-time and non-real-time quality of service classes, provided that wireless microphones temporal activity is moderate (with approximately one wireless microphone per 3,000 inhabitants with light urban population density and short duty cycles). Finally, two-stage spectrum sensing option improves OS-OFDMA throughput, provided that the length of spectrum sensing at every stage is optimized using our model.