Outage evaluation for slow frequency-hopping mobile radio systems

Abstract

In a shadowing-free environment, the improvement introduced by slow frequency-hopping (SFH) on a time-division multiple-access based mobile radio system can be taken into account by redefining the minimum carrier-to-interference ratio. This protection ratio, with SFH, is dependent on the transmission system, channel model, traffic, and frequency reuse parameters. In this paper, the above-mentioned analysis is used in order to investigate the capacity of a SFH mobile radio system, with reference to both the uplink and downlink, by taking into account a complete scenario, i.e., shadowing, fast fading, power control, antenna diversity, discontinuous transmission, and forward error correction with nonideal interleaving and sectorization. Outage probability is evaluated by a completely analytical methodology for the uplink, whereas the downlink requires a semianalytical approach to take users' positions into account. Comparison with a pure simulative approach is used to validate the results

Does Fast Adaptive Modulation Always Outperform Slow Adaptive Modulation?

“…Composite Rayleigh fading and log-normal shadowing channels are considered with both ideal and nonideal channel estimation. 5 For non-ideal channel estimation, the ASE is evaluated by (19), with a target BEP of 10 −2 and a maximum BEO of 5% (typical values for uncoded systems). We denote by the ratio between the frame lengths with SAM and FAM (i.e., the ratio of the coherence time, for largeand small-scale fading), as…”

“…. ℎ d ] is constant over a frame, and independent frame by frame (block fading channel [17]- [19]). The estimated fading gain on the -th branch iŝ…”

“…The ASE can still be evaluated from (18) and (19), with ( ) = T ( ). The CDF ofˆT can be derived from the marginal PDF ofˆT( ) = ∫ˆT | ( ) ( ) , where the conditional PDF isˆT…”

Analytical Modeling of Interference in Cellular Fixed Relay Networks

“…Indeed, the power received from an interferer in a wireless context, when averaged over time and position, can be well modeled by a lognormal RV, even when other factors multiply the power received from each interferer (Rayleigh fading, pathloss) [4]. In particular, the downlink analysis in cellular systems has been considered problematic, since it involves the sum of correlated random variables [6]. We propose an approximate solution which consists in finding the exact moments of the interference power.…”

Column generation for frequency assignment in slow frequency hopping networks

“…Signals at a specific location are no longer either very bad (unusable) or very good (inefficient) the whole time, though bad conditions on isolated time frames are still very possible since they can be easily corrected via error recognition codes. Here we refer to [6][7][8] for more information. Thus, randomization effectively lowers the network's signal-to-noise ratio, resulting in an increased capacity or improved transmission quality compared to non-hopping networks.…”