摘要 :
In this paper, we investigate the performance of two-way interference-limited amplify-and-forward relaying systems over independent, non-identically distributed Nakagami-m fading channels. Our analysis generalizes several previous...
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In this paper, we investigate the performance of two-way interference-limited amplify-and-forward relaying systems over independent, non-identically distributed Nakagami-m fading channels. Our analysis generalizes several previous results, since it accounts for interference affecting all network nodes. In particular, tight lower bounds on the end-to-end outage and symbol error probability are derived in closed-form, while a useful expression is presented for the asymptotically low outage regime. Some special cases of practical interest (e.g., no interference power and interference-limited case) are also studied. Using the derived lower bounds as a starting point and for the case of Rayleigh fading, we formulate and solve analytically three practical optimization problems, namely, power allocation under fixed location for the relay, optimal relay position with fixed power allocation, and joint optimization of power allocation and relay position under a transmit power constraint. The numerical results provide important physical insights into the implications of model parameters on the system performance; for instance, it is demonstrated that relay position optimization offers significant performance enhancement over the non-optimized case for an asymmetric interference power profile, whilst the optimization gains are marginal for a symmetric one.
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摘要 :
Blind signal classification, a major task of intelligent receivers, has important civilian and military applications. This problem becomes more challenging in multi-antenna scenarios due to the diverse transmission schemes that ca...
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Blind signal classification, a major task of intelligent receivers, has important civilian and military applications. This problem becomes more challenging in multi-antenna scenarios due to the diverse transmission schemes that can be employed, e.g., spatial multiplexing (SM) and space-time block codes (STBCs). This paper presents a class of novel algorithms for blind classification of SM and Alamouti STBC (AL-STBC) transmissions. Unlike the prior art, we show that signal classification can be performed using a single receive antenna by taking advantage of the space-time redundancy. The first proposed algorithm relies on the fourth-order moment as a discriminating feature and employs the likelihood ratio test for achieving maximum average probability of correct classification. This requires knowledge of the channel coefficients, modulation type, and noise power. To avoid this drawback, three algorithms have been further developed. Their common idea is that the discrete Fourier transform of the fourth-order lag product exhibits peaks at certain frequencies for the AL-STBC signals, but not for the SM signals, and thus, provides the basis of a useful discriminating feature for signal classification. The effectiveness of these algorithms has been demonstrated in extensive simulation experiments, where a Nakagami-m fading channel and the presence of timing and frequency offsets are assumed.
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摘要 :
An alternative, unified, semi-analytical approach for the evaluation of the cumulative distribution function (cdf) of the weighted sum of L independent Rician (or Rayleigh as a special case) and m-Nakagami envelopes with or withou...
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An alternative, unified, semi-analytical approach for the evaluation of the cumulative distribution function (cdf) of the weighted sum of L independent Rician (or Rayleigh as a special case) and m-Nakagami envelopes with or without the presence of Additive White Gaussian Noise (AWGN) is presented. The cdf is evaluated directly in a nested mode via the Hermite numerical integration technique. The proposed formulation avoids the calculation of complex functions and can be efficiently applied to practical wireless applications when L ≤ 3, using arbitrary statistical characteristics for the modeling parameters. Moreover, it can be also used to control the accuracy of other techniques when L > 3. Comments, comparison with other existing techniques and useful curves for several practical wireless applications such as the calculation of the error bounds for coding on fading channels in mobile satellite applications and the Equal Gain Combining (EGC), are also presented. Finally, the relation between the distribution of the sum of m-Nakagami and Rice envelopes is investigated and discussed.
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