This paper studies the effects of the sub-carrier grouping on the scheduling problem in a wireless network with multiple carriers. In particular, the authors consider the trade-offs between the size of the sub-carrier groups and the link throughput for various sub-carrier grouping models, with each corresponding to a different level of CSI tracking and system design complexity. The paper assumes that a single user is communicating with the base station using the entire sub-carriers. This assumption is motivated by the OFDM, which uses multiple carriers in order to benefit from the frequency selective fading introduced by spreading the information bits over the entire signal band. An offline dynamic programming algorithm for finding an optimal solution for the case of spectrum- and time-perfect estimates is also presented. The performance can potentially be improved by using high-level modulation on the sub-carriers with good channel conditions.

For next generation wireless cellular networks, the radio access network (RAN) component is destined to evolve into a high-capacity, flexible and reconfigurable network architecture supporting smaller cell sites and newer technologies. Based on the well-known Petersen graph, in this paper we propose a RAN architecture, named PeterNet, that interconnects the network elements in a mesh topology. Focusing on optical wireless as the underlying transmission technology, we analyze our architecture on two key indices - carrier-class network reliability (99.999%) and infrastructure cost - providing comparative performance analysis with existing tree/star and regular grid networks. Furthermore, we generalize our architecture to what we call, the GPeterNet, which allows dynamic reconfiguration and redesign of the access network while leveraging the underlying salient features.

Traditionally, the routing problem is addressed at the network layer, an approach that has been extended to the wireless realm. In wireless multihop networks, however, strict layer-base protocol design leads to substantial inefficiencies. This paper addresses the routing problem for large wireless ad hoc networks from a fundamental point of view, not constrained by particular protocol implementations or layered architectures, but taking into account the properties of the wireless channel. First, an analytical channel model is presented that is based on Rayleigh fading. It demonstrates how noise and interference effects can be separated, and how each interfering transmission affects the packet reception probability. Second, the distribution of node distances in networks with uniformly randomly placed nodes is derived. These two ingredients are used to discuss the benefits of different routing strategies. In particular, short-hop and long-hop routing schemes are compared. Further, cooperative strategies such as multipath routing and cooperative diversity are briefly discussed as techniques that are enabled by the broadcast nature of the wireless channel.

In this paper, we present a novel fully distributed version of a mobile backbone network topology synthesis algorithm (MBN-TSA) for constructing and maintaining a dynamic backbone in mobile wireless ad hoc networks. The following features induce the key advantages offered by the algorithm: a) the MBN-TSA algorithm is designed to work with the unreliable natural of wireless environment; b) the backbone layout is dynamically formed and locally modified in response to communications link quality fluctuations, nodal failures and nodal mobility; c) a control mechanism employing the BN_neighbor_limit threshold as a key parameter, is introduced to control the size of the backbone network (BNet) and improve stability; d) analytical results show that the MBN-TSA has very little control overhead: time complexity in the order of O(l) and message complexity in the order of O(l) per node. In addition, we present an on-demand routing protocol that makes use of the underlying dynamically self-configured MBN network infrastructure. By carrying out extensive simulations, we demonstrate the performance advantages when compared to a non backbone oriented on-demand ad hoc routing protocol such as AODV.

We introduce a new protocol based on the optical-burst-switched (OBS) transport to support synchronous services such as SONET/SDH. We term this protocol synchronous optical burst switching (SOBS) and describe the problems and challenges of supporting both synchronous and asynchronous traffic with various bandwidth granularities. We discuss the problems of path signaling, periodic reservations, and burst framing. We also highlight the importance of burst-level grooming, develop related analytical formulations, and present results of various simulations.