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Recently, it is widely believed that significant coverage and performance improvement can be achieved through the deployment of small cells in conjunction with the well-established macro cells. However, it is expected that the high density of base stations in such heterogeneous cellular networks will give rise to multiple design problems related to both co-tier (small-to-small) and cross-tier (between small and macro cells) interference. Fortunately, cooperation between base stations will play a major role to cope with these problems and hence to enhance the users' data rates. In this paper, we consider a two-tier cellular network comprised of a macro cell underlaid with multiple small cells where both co-tier and cross-tier interference are taken into account. We study the scenario where the small cell base stations seek to maximize a common objective by forming multiple clusters through cooperation. These base stations have also to allocate power to their associated users and, at the same time, control the total aggregate interference caused to the macro cell user which has to be kept below a threshold prefixed by the macro cell base station. We consider two utility functions: the overall sum rate of the small cell network and the minimum data rate of the small cell users. We formulate the studied problems as mixed integer nonlinear optimization problems and we discuss their NP hardness. Therefore, due to the complexity of finding the optimal solution, we design heuristic algorithms which resolves efficiently the tradeoff between computational complexity and performance. We show through simulations that the designed heuristics approach the optimal solution (obtained using the complex exhaustive search algorithm) with highly reduced computational complexity. [ABSTRACT FROM AUTHOR]

Wireless mesh networks (WMNs) are expected to be widely deployed due to their ability to provide ubiquity, convenience, cost-efficiency, and simplicity for both service providers and end-users. Recently, the IEEE 802.11s standard introduces the hybrid wireless mesh protocol (HWMP) which is inspired by a combination of on-demand and tree-based pro-active routing algorithms. In this paper, we argue that the proposed unimetric path selection algorithm in the standard is not reliable. We introduce and examine a novel multimetric wireless mesh path selection algorithm using fuzzy decision making under realistic wireless channel conditions. The proposed path selection algorithm is designed to improve the performance of both re-active and pro-active routing protocols of HWMP for not only single-channel but also multi-channel WMNs. The reported results show the superior performance of the proposed path selection algorithm in terms of delay and packet delivery ratio without increasing overhead significantly. Although some fuzzy-based routing algorithms have been defined in literature recently, to the best of our knowledge, this paper is the first one to introduce and examine the use of fuzzy logic in the path selection of single- and multi-channel wireless local area network-based WMNs under realistic wireless channel conditions. [ABSTRACT FROM AUTHOR]

Resource scheduling and routing tree construction in WiMAX mesh centralized scheduling are not defined in the standard and thus are subject to extensive research. In this paper, we consider routing and scheduling in a WiMAX-based mesh network. We assume that nodes are not necessarily stationary, but rather mobile with a mobility that may yield to frequent topology changes (e.g., failure of existing links and creation of new transmission links). We model the joint routing and scheduling as an optimization problem whose objective is either to determine a minimum length schedule by maximizing spectrum spatial reuse or maximizing the network lifetime by routing around the less stable RF-links, while satisfying a set of (uplink/downlink) end-to-end demands. While solving the problem with the two objectives, we study the tradeoffs between these two objectives. We show that minimizing the schedule length forces the joint routing and scheduling problem to generate a routing tree and feasible transmission groups which favor higher spectrum spatial reuse (and hence higher system throughput), irrespective of the robustness of the selected transmission links. In addition, we show that maximizing the network stability or lifetime yields the selection of different routing trees and slot assignments which do not necessarily result in shorter schedule length. We perform numerical experiences where we compare the performances of our proposed models with respect to the network stability and resource spatial reuse. [ABSTRACT FROM AUTHOR]

An introduction to the journal is presented in which the editor discusses a research on the latest advances in mobile computing, networking, and wireless communications.

This work focuses on developing and implementing comprehensive unified constraint-based routing algorithms within the generalized multi-protocol label switching framework (GMPLS) to provision “sub-wavelength” circuits (low-rate traffic streams). Constraint-based routing is further augmented in this work by dynamically routing both an active and another alternate link/node-disjoint backup path at the same time in order to provision a given connection request. This new integrated approach combines both IP routing and optical resource allocation to setup end-to-end connections. [ABSTRACT FROM AUTHOR]