Mohamed Elwekeil

Lagrangian relaxation approach for low complexity channel assignment in multi-cell wlans

The Channel assignment problem for multi-cell WLANs is important due to the lack of free available channels. Usually, this problem can be formulated as a mixed integer linear program (MILP) which requires high combinatorial complexity. In this paper, a lagrangian relaxation technique is used in order to transform the MILP into a low complexity linear program. Simulation results show that the proposed channel assignment algorithm provides significant reduction in complexity compared to the MILP counterpart at the expense of insignificant increase in total interference-sum at Access Points (APs). It is also suggested that the benefits of reduced complexity outweigh the increased interference.

Dynamic autonomous frequency reuse for uplink cellular networks

In this paper, a dynamic autonomous frequency reuse strategy is adopted for resource allocation in uplink cellular networks. It is assumed that each cell is divided into inner and outer regions. The proposed approach is based on minimizing the total uplink interference at every eNB for all users in both the inner and outer regions in the network. The main advantage of the proposed scheme is that it adapts itself to the varying wireless channel. Simulation results show that the proposed approach provides better total network uplink throughput and average user uplink bit rate compared to the traditional fractional frequency reuse (FFR) regardless of the User Equipment (UE) transmit power, cell radius and user density within the cell.

Efficiency of opportunistic cellular/LiFi traffic offloading

Data offloading efficiency in a cellular/light fidelity network is investigated. This offloading efficiency is a measure of the ratio of traffic carried by light fidelity (LiFi) network to total traffic carried by both LiFi and cellular networks. The effect of LiFi-signal blocking and channel characteristics are considered. Different LiFi offloading timing cases are discussed. Simulation is performed in order to explore the performance of opportunistic cellular/LiFi traffic offloading scenario. Simulation results reveal that LiFi-signal blocking can reduce the offloading efficiency by more than 30%.

WLAN Channel Assignment Based on Minimizing the Worst-Case Interference

An optimization model for solving the channel assignment problem in multi-cell WLANs which is based on minimizing the maximum interference at access points in the network is proposed. The channel assignment problem is formulated as a mixed integer linear program. The main advantage of the proposed model is that it guarantees that the worst access point interference is minimized. Simulation results show that the proposed model provides both the least worst access point interference and the best fairness, compared to the pick-first greedy algorithm, the optimum model and the maxmin model.