Fading distribution

About: Fading distribution is a research topic. Over the lifetime, 5732 publications have been published within this topic receiving 114193 citations.

Another look at the performance of MRC schemes in Nakagami-m fading channels with arbitrary parameters

Abstract: In this letter, we take a close look at the performance of maximal ratio combining (MRC) schemes operating in a flat-Nakagami-m fading environment with arbitrary fading parameters. We derive an expression for the probability density function (pdf) of the output signal-to-noise ratio (SNR) by expressing the moment generating function of the output SNR in the form of multiple Barnes-type contour integrals. By evaluating the inverse transform and converting the multiple contour integrals into infinite series, we are able to derive an expression for the pdf of the output SNR when the Nakagami fading parameters along the diversity branches take on real and arbitrary values. Consequently, the average bit-error rate can now be expressed in terms of Lauricella's multivariate hypergeometric function, which can be easily evaluated numerically. Special cases of the main results reduce to known results in the literature. The results, which apply to independent as well as correlated diversity branches, will be useful for predicting the system performances when the Nakagami fading parameters are real and arbitrary.

Design and analysis of transmitter diversity using intentional frequency offset for wireless communications

Abstract: Coded modulation (usually with interleaving) is used in fading channel communications to achieve a good error performance. The major benefit from using coded modulation in fading channels is achieved if each code symbol of a codeword (or coded sequence) suffers statistically different fading (preferably independent fading). However, in many applications of mobile communications (e.g., in a metropolitan environment), a low vehicle speed (and hence, a small Doppler spread, f/sub D/) is very common. With a small Doppler spread, ideal or close-to-ideal interleaving is no longer feasible and all code symbols of a codeword would suffer highly correlated fading especially in stationary fading (f/sub D//spl ap/0). Coded modulations will thus suffer seriously degraded performance. Previous performance analyses based on ideal interleaving are not accurate when a small Doppler spread is encountered and the much used union bound error probability analysis is loose for small Doppler spreads. To rectify this situation, this paper presents an improved performance analysis of coded modulations with correlated fading and pilot-symbol-assisted modulation (PSAM). Transmitter diversity can generate the necessary time-varying fading to maintain the effectiveness of a coded signaling scheme which this paper examines in detail using an intentional frequency offset between antennas. This work found that proper selections of the intentional frequency offset and interleaving depth can lead to good performance with traditional coded modulations (if enough antennas are used) using essentially the same simple demodulation structure as used in the traditional single-antenna PSAM.

Co-channel interference of microcellular systems on shadowed Nakagami fading channels

Abstract: The probability of cochannel interference is evaluated for a microcellular environment with log-normal shadowing and Nakagami fading. For the case when the interfering signals have the same shadowing and fading statistics, an exact mathematical expression is presented for the probability of cochannel interference. For the case when the interfering signals have different shadowing and fading statistics, the probability of cochannel interference is evaluated by approximating the individual interfering signals as having a log-normal distribution, and then applying Schwartz and Yeh's method to obtain a purely log-normal distribution for total interference, while maintaining a composite Nakagami log-normal distribution for the desired signal.

Performance Analysis of Dual-Hop AF Systems With Interference in Nakagami- $m$ Fading Channels

Abstract: In this letter, we investigate the performance of dual-hop channel state information-assisted amplify-and-forward relaying systems over Nakagami-m fading channels in the presence of multiple interferers at the relay. Assuming integer fading parameter m, we derive closed-form expressions for the exact outage probability and accurate approximation for symbol error rate of the system. Furthermore, we look into the asymptotical high signal to noise ratio regime, and characterize the diversity order achieved by the system. All the analytical results are validated via Monte Carlo simulations.

Capacity and optimal power allocation for fading broadcast channels with minimum rates

Abstract: We derive the capacity and optimal power allocation scheme for a multiuser fading broadcast channel in which minimum rates must be maintained for each user in all fading states, assuming perfect channel state information at the transmitter and at all receivers. We show that superposition coding can achieve the capacity of such channels and explicitly characterize the boundary of the capacity region. The optimal power allocation scheme is a two-step process: we first allocate the minimum power required to achieve the minimum rates in all fading states, and we then optimally allocate the excess power to maximize the ergodic rates averaged over all fading states in excess of the minimum rate requirements. The optimal allocation of the excess power is a multi-level water-filling relative to effective noise that incorporates the minimum rate constraints. Numerical results are provided for different fading broadcast channel models.