This paper proposes an architecture for mobile wireless networks based on Radio-over-Fiber (RoF) technology. The architecture organizes cells in a multi-tier fashion, with different tiers covering areas with different radii lengths. Proposed optimization algorithm splits cells to improve network capacity in congested areas and merges cells when the demand is low. The evaluation of the effectiveness of the proposed model considered three distinct objectives: minimization of the number of base stations used, maximization of the number of users served, and minimization of network energy consumption. The combination of the first two objectives was also evaluated. Three algorithms based on linear relaxation techniques are introduced for rapid computation of the near-optimum solutions. The proposed architecture is shown to lead to network infrastructures that save costs and energy and yet provide service to a large number of users.

In this paper, two Medium Access Control (MAC) protocols exclusively tailored to WSNs over RoF (RWSNs) namely SPP-MAC (Scheduled Priority Polling Medium Access Control) (polling-based) and HMARS (Hybrid Medium Access Control for Hybrid Radio-over-Fiber Wireless Sensor Network Architecture) (hybrid-based) are proposed. They deal with the main problems in RWSNs i.e. the delay imposed by optical fiber and the existence of two collision domains: the wireless and the fiber optical links. The performance of these two protocols evince their effectiveness for the connection of WSNs by RoF links.

This article presents a radio resource optimization model for Radio-over-Fiber (RoF) access networks. The proposed model arranges cells in a multi-tier fashion with increasing coverage radius. Considering the available structure of antennas the optimizer performs dynamic cell merging and cell splitting according to mobile users' demands for efficiently utilizing radio resources. It is proposed an integer programming model with a bi-criteria objective function that tries to minimize the use of network resources as well as to maximize network revenue. The computational demand for obtaining integer solutions increases proportionally to the number of mobile users and also to the number of tiers of antennas. In addition to the integer solutions, an algorithm based on linear relaxation technique is presented, which implies on significant computational time reduction when solving large instances of the problem. Moreover, results are very close to those given by the integer programming formulation.

In this paper, we introduce a radio resource optimization model for Radio-over-Fiber (RoF) access networks. We propose a mixed integer programming model to minimize the network cost while providing service to all mobile users. The proposed architecture arranges cells in a multi-layer fashion, with cells in each layer providing different coverage radius. The optimization algorithm performs dynamic cell splitting to improve network capacity in congested areas and cell merging in areas with low demand to save resources. The computational demand of the proposed model increases proportionally to the number of layers of RAUs in the infrastructure. Results indicate that two layers of RAUs give the best trade-off between network cost reduction and computational demand.

This article investigates VoIP performance over WLAN (WVoIP) through qualitative and quantitative point of view, considering degradation with the mobility. The results was obtained through a channel emulator to produce the Weibull distribution. Measurements results with a robot showed that this distribution is adequate to represent WLAN environment instability. The test utilized the CODECs G711 and GSM. The article presents preliminary results that indicate the effect of the instability of wireless environment in the VoIP performance. The results indicate a significant variation of voice quality, considering the severity of the phenomena emulated. The behaviors of the CODECs are evaluated considering the different characteristics of bandwidth and robustness.

WLAN 802.11 operating in 2,4 GHz are being intensely implanted mainly in public environments. In these environments mobility is always a present characteristic. The objective of this work is to analyze the behavior of 802.11 MAC with flat fading. To reach this objective an emulation system was developed to create the flat fading channel phenomenon. With a WLAN and the emulator was possible to show the cross layer effect, evaluating the WLAN performance analyzes in mobility conditions. The experiments evaluated: rate of tansmission in each modulation level, data rate in the transport layer, network efficiency, jitter and throughput. The network information was obtained through SNMP. The results show that the 802.11 MAC had problems to support services that need high performance, as VoIP and Streaming. Therefore when the receiver is in movement the degradation does not allow the quality required by these types of services.