Learn More
We consider scheduling and resource allocation for the downlink of a OFDM-based wireless network. During each time-slot the scheduling and resource allocation problem involves selecting a subset of users for transmission, determining the assignment of available subcarriers to selected users, and for each subcarrier determining the transmission power and the(More)
—In this paper we establish the log-convexity of the rate region in 802.11 WLANs. This generalises previous results for Aloha networks and has immediate implications for optimisation based approaches to the analysis and design of 802.11 wireless networks. I. INTRODUCTION In this paper we consider the log-convexity of the rate region in 802.11 WLANs. The(More)
—Médard and Gallager recently showed that very large bandwidths on certain fading channels cannot be effectively used by direct sequence or related spread-spectrum systems. This paper complements the work of Médard and Gallager. First, it is shown that a key information-theoretic inequality of Médard and Gallager can be directly derived using the theory of(More)
—Orthogonal Frequency Division Multiplexing (OFDM) with dynamic scheduling and resource allocation is a key component of most emerging broadband wireless access networks such as WiMAX and LTE (Long Term Evolution) for 3GPP. However, scheduling and resource allocation in an OFDM system is complicated, especially in the uplink due to two reasons: (1) the(More)
—The capacity and the reliability function as the peak constraint tends to zero are considered for a discrete-time memoryless channel with peak constrained inputs. Prelov and van der Meulen showed that under mild conditions the ratio of the capacity to the squared peak constraint converges to one-half the maximum eigenvalue of the Fisher information matrix(More)
The goal of this thesis is to understand how to achieve capacity for wireless fading channels with emphasis on the role of the burstiness in both time and frequency of the transmitted signals. Typical signal design constraints for a communication system are concerned primarily with regulating the transmitted power. This allows for signals of diiering(More)
—In a limited form cellular providers have long shared spectrum in the form of roaming agreements. The primary motivation for this has been to extend the coverage of a wireless carrier's network into regions with no infrastructure. As devices and infrastructure become more agile, such sharing could be done on a much faster timescale and have advantages even(More)
We consider a single server discrete-time system with K users where the server picks operating points from a compact, convex and co-ordinate convex set in R<sub>+</sub> <sup>K</sup>. For this system we analyse the performance of a stablising policy that at any given time picks operating points from the allowed rate region that maximise a weighted sum of(More)
We characterize the (nonconvex) rate region and its maximal convex subsets for carrier-sense multiple-access with collision-avoidance (CSMA/CA) wireless local-area networks (WLANs), and in particular for 802.11 WLANs. In addition to being of intrinsic interest as fundamental properties of CSMA/CA WLANs, this characterization can be exploited to allow the(More)