Performance Analysis of Hybrid Relay Selection in Cooperative Wireless Systems

The packet error rate (PER) is a metric of choice to compute the practical performance of communication systems experiencing block fading, e.g., fading processes whose coherence time is relatively slow when compared to the symbol transmission rate. For these types of channels, we derive a closed-form asymptotic expression which approximates the value of the PER for high signal-to-noise ratio (SNR). We also provide another approximation based on a unit-step formulation of the symbol error rate (SER). We show that the two approximations are related and may be derived from one another, thereby allowing us to obtain closed-form approximations of the block fading PER in both coded and uncoded systems. We then show how these approximations may be used in practice, through the derivation of a packet error outage (PEO) metric covering the case where the links experience shadowing on top of block fading, as well as asymptotically optimal power allocations in relay channels under a block fading hypothesis.

Section: Corollary 1 For Fading Channels Whose Pdf Verify the Conmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 95%

See 1 more Smart Citation

Approximations of the packet error rate under quasi-static fading in direct and relayed links

Ferrand

Gorce

Goursaud

2015

“…In half-duplex-based cooperative relay networks, the channel of source-to-destination (SD) link has been modeled as a time-invariant channel during the two transmission phases [4,[7][8][9][10][11]. According to the assumption, it is well known that the cooperative relaying schemes are more beneficial than repeated transmission (RT), which simply transmits the same signal twice through the SD link, at high-SNR region due to its diversity gain.…”

Section: Introductionmentioning

confidence: 99%

Availability of direct path in half‐duplex‐based cooperative relay networks

Lee

Kim

2015

In this paper, we validate the availability of direct path in half-duplex-based cooperative relay networks from a practical point of view. Cooperative relaying is a low-complexity technique, which schedules orthogonal transmissions through the divided time slots. By doing so, transmission impairments due to multi-path fading and path loss are mitigated by obtaining a diversity gain. In conventional approaches, most researchers have focused on a role of relay and assumed that the received signal-to-noise ratio in source-to-destination link is doubled when source transmits the same signal twice during the two transmission phases. However, in practical wireless environments, a wireless channel is not static but varies with time. Thus, although the source retransmits the same signal during the second transmission phase instead of forwarding by a relay, the (time) diversity gain may be obtained. As a result, the performance of relaying-aided cooperative communication is not always better than that of the repeated transmission (RT), but the RT scheme may be a better option than a cooperative relaying scheme. To this end, we first show that the RT scheme is comparable to conventional cooperative relaying schemes. We then propose a selection decode-and-forward (DF) relaying scheme, which combines the DF relaying and RT schemes. The proposed selection DF relaying scheme has better outage performance than comparable relaying schemes in time-varying channels. Lastly, all the theoretical results are validated through numerical evaluations and Monte Carlo simulations.

“…Relay-assisted communication is suitable to solve the problem and plays a main role in the future generation cellular systems and ad hoc networks [4]. One form of relayassisted communication is cooperative diversity [5,6]. Its principle is to exploit the broadcast nature of wireless transmission and creates a virtual antenna array through cooperating users.…”

Section: Introductionmentioning

confidence: 99%

Performance analysis of two-user cooperative ARQ protocol over Rayleigh fading channel

Xiao

2015

In this paper, we present a two-user cooperative automatic repeat request (C-ARQ) protocol which combines cooperative diversity at the physical layer and ARQ at the link layer. In this scheme, distributed Alamouti space-time block coding (DASTBC) is applied to achieve cooperative diversity, and ARQ is used to improve the data link layer reliability. To analyze the performance of the proposed protocol, we derive the average frame error rate (FER) and throughput with multiple phase shift keying (MPSK) over a Rayleigh fading channel. Numerical simulation results show that the performance gain of average FER with ARQ retransmission is about 2 dB more than the case without ARQ retransmission in the same conditions. Moreover, the combined DASTBC and quadrature phase shift keying (QPSK) with ARQ retransmission will lead to an approximate 3 Mbits/s increase in transmission rate.