Rate-optimal and reduced-complexity sequential sensing algorithms for cognitive OFDM radios

Abstract

Sequential sensing algorithms are developed for OFDM-based hierarchical cognitive radio (CR) systems. Secondary users sense multiple sub-bands simultaneously for possible spectrum availabilities under hard miss-detection constraints to prevent interference to the primary users. Accounting for the fact that the sensing time overhead can often be significant, a performance metric is developed based on the effective achievable data rate. An optimization problem is formulated in the framework of optimal stopping problems to maximize the average effective data rate by determining the best time to stop taking samples for sensing, as well as the best set of channels to use for data transmission. A basis expansion-based sub-optimal algorithm is derived to reduce the prohibitive complexity of the optimal solution.

Adaptive spectrum sensing for agile cognitive radios

“…Unlicensed (secondary) users can therefore monitor the frequency spectrum and identify and opportunistically exploit under-utilized spectrum segments (spectrum holes). This monitoring task, often referred to as spectrum sensing, is a major aspect of cognitive radio and has received a considerable amount of research interest [1][2][3][4]. The detection a spectrum hole in a wideband spectrum involves two major challenges.…”

Improving Spectrum Sensing Performance by Exploiting Multiuser Diversity

“…Secondary users have the ability to access all of the available channels by switching frequencies. Multichannel cognitive radio networks have been studied in (Jiang et al, 2008;Kim & Giannakis, 2009;Min & Shin, 2008). For example, in (Jiang et al, 2008;), a cognitive radio system with opportunistic transmissions is considered wherein the secondary user not only senses a channel to decide whether it is free, but also estimates the channel coefficients in order to determine the transmission rate.…”

“…It is known that SPRT minimizes the average sample number (ASN) among all tests with the same false alarm and detection probabilities. In (Kim & Giannakis, 2009), sequential sensing is proposed for orthogonal frequency division multiplexing (OFDM) cognitive radios. Lai et al ) develop a sequential sensing strategy based on a quickest detection framework.…”

Exploiting Multichannel Diversity in Cognitive Radio Networks

“…In [10], a channel-aware switching algorithm was developed to decide where and when to switch among the candidate channels. Sequential temporal sensing algorithms were developed for OFDM-based hierarchical cognitive radio systems in [13]. In all of the aforementioned works, only pure temporal spectrum sensing was considered.…”

“…, N . Multichannel cognitive radio networks have been studied in [10]- [13]. In [11], [12], a dynamic programming approach was proposed to search for an optimal sensing order among the channels.…”