Abstract
Subcarrier mapping (SCM) is considered to be crucial for capacity-maximization in an orthogonal frequency division multiplexing (OFDM) relaying network. Although SCM in an OFDM system has been investigated extensively, nevertheless, the outage probability and outage capacity analysis of the system is not yet available in the literature. This paper presents the outage analysis of a dual-hop OFDM relay system with ordered subcarrier paring schemes, i.e., worst-to-best (WTB) SCM and best-to-best (BTB) SCM. Accurate close-form expressions are derived for end-to-end outage while considering a dual-hop fixed gain amplify-and-forward (AF) relaying system with Rayleigh fading channel model. The first and second moments of end-to-end signal-to-noise ratio (SNR) and capacity are derived for WTB SCM and BTB SCM schemes while approximating the probability distribution function (PDF) of total capacity of each subcarrier pair by Gaussian distribution. The outage performances of these schemes are compared with balanced links, i.e., when the SNR is same for both hops, as well as unbalanced links, i.e., when the SNR of the second hop is one half of the SNR of the first hop. The numerical results validate the analysis in Rayleigh fading channel.
Highlights
Orthogonal frequency division multiplexing (OFDM) is the key element of long-term evolution (LTE) while a multi-hop network increases the coverage area of transmission and provides significant performance improvement as a result of cooperative diversity
As the outage probability and outage capacity are important performance measuring parameters of a wired/wireless communication system; in this paper we focus on the performance comparison of the dual-hop OFDM AF relay system with WTB Subcarrier mapping (SCM) and BTB SCM schemes on the basis of outage probability and outage capacity
6 Conclusions The outage performance of the dual-hop OFDM fixed gain AF relay system is analyzed in Rayleigh fading with BTB SCM and WTB SCM
Summary
Orthogonal frequency division multiplexing (OFDM) is the key element of long-term evolution (LTE) while a multi-hop network increases the coverage area of transmission and provides significant performance improvement as a result of cooperative diversity. Subcarrier mapping (SCM), which is considered to be a capacity-maximization scheme for a dual-hop OFDM relay system, is studied extensively in the literature [6,7,8,9,10,11,12,13,14,15,16]. The above literature provides analysis of outage probability and outage capacity for an OFDM system, yet these do not consider ordered SCM schemes in a dual-hop OFDM relaying system which is challenging due to its inherited complexity. A thorough comparison on the basis of outage probability and outage capacity for the dual-hop OFDM relay system with BTB SCM and WTB SCM is presented which is not available in the previous literature.
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