Vijay G. Subramanian

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—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)
—We consider scheduling and resource allocation for the downlink of a cellular OFDM system, with various practical considerations including integer carrier allocations, different subchannelization schemes, a maximum SNR constraint per tone, and " self-noise " due to channel estimation errors and phase noise. During each time-slot a subset of users must be(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)
—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)
—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)
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)
—We consider a single server discrete-time system with K users where the server picks operating points from a compact, convex and coordinate convex set in K +. 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 rate, where the weights(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)
We consider scheduling and resource allocation for the downlink in a CDMA based wireless network. The scheduling and resource allocation problem is to select a subset of the users for transmission and for each of the users selected, to choose the modulation and coding scheme, transmission power, and number of codes used. We refer to this combination as the(More)