No abstract

Abstract-Using Wi-Fi with femtocell is a promising approach to solve the problem of inter-tier or intra-tier interference in heterogeneous networks. In our scenario, Wi-Fi femtocells are deployed to form a mesh network (Wi-Fi) which is used by mobile users as an access network to the macro cellular one (e.g., LTE), extending consequently, the coverage to poorly covered areas. We propose a tractable model for coverage/outage to evaluate the benefits of such integration in terms of SINR and received signal strength. Our work is based on point processes in two-dimensional plane that models locations of femtocell/WiFi nodes (also referred to as multimode nodes). The proposed model is more realistic than the classical Poisson point process, as the distribution of points is more homogeneous and it ensures that the nodes are not too close to each other. The derivation of coverage/outage formula allows us to determine operational parameter ranges for the Wi-Fi network to form a mesh network. In addition, it helps in the design of the femtocell network to ensure a suitable coverage for users in terms of SINR and received signal strength.

Internet predominant transport protocols, such as TCP and TFRC, face degradation of their performance in Multihop Wireless Networks because of their high loss and link failure rates. Many solutions have been proposed to improve the transport layer operation. These solutions are either based on network state estimation or use information from MAC layer (called MAC metrics) in a cross-layer manner to better comprehend the network state. In this paper, we define a new MAC metric called Medium Access Delay (MAD) to better reflect the network state, and provide a comparative study of MAD over other pertinent MAC metrics, their expected usage and measurement methods at MAC layer. We also investigate the behaviors of MAC metrics through several experiments in order to reveal their effectiveness in reflecting network events such as contention, collision and losse.