Channel allocation schemes

About: Channel allocation schemes is a research topic. Over the lifetime, 10656 publications have been published within this topic receiving 182117 citations.

On Providing Downlink Services in Collocated Spectrum-Sharing Macro and Femto Networks

Abstract: Femtocells have been considered by the wireless industry as a cost-effective solution not only to improve indoor service providing, but also to unload traffic from already overburdened macro networks. Due to spectrum availability and network infrastructure considerations, a macro network may have to share spectrum with overlaid femtocells. In spectrum-sharing macro and femto networks, inter-cell interference caused by different transmission powers of macrocell base stations (MBSs) and femtocell access points (FAPs), in conjunction with potentially densely deployed femtocells, may create dead spots where reliable services cannot be guaranteed to either macro or femto users. In this paper, based on a thorough analysis of downlink (DL) outage probabilities (OPs) of collocated spectrum-sharing orthogonal frequency division multiple access (OFDMA) based macro and femto networks, we devise a decentralized strategy for an FAP to self-regulate its transmission power level and usage of radio resources depending on its distance from the closest MBS. Simulation results show that the derived closed-form lower bounds of DL OPs are tight, and the proposed decentralized femtocell self-regulation strategy is able to guarantee reliable DL services in targeted macro and femto service areas while providing superior spatial reuse, for even a large number of spectrum-sharing femtocells deployed per cell site.

Quality of Service Scheduling for 802.16 Broadband Wireless Access Systems

Abstract: IEEE 802.16, the specification for fixed, portable and even mobile Broadband Wireless Access (BWA) systems, is promising to support heterogeneous classes of traffic with differentiated Quality of Service (QoS). The proposed Medium Access Control (MAC) protocol defines a wide variety of mechanisms for bandwidth allocation and QoS provision. However, the details of how to schedule traffic are left unspecified so that the vendor may differentiate their product through implementation. In this paper, a new and efficient QoS scheduling strategy based on the hierarchical and distributed architecture is proposed for 802.16 BWA systems. Analytical and simulation results show that the proposed scheduling architecture can provide QoS guarantees for all types of traffic as defined in the standard.

Interference-Resilient Information Exchange

Abstract: This paper presents an efficient protocol for reliably exchanging information in a single-hop, multi-channel radio network subject to unpredictable interference. We model the interference by an adversary that can simultaneously disrupt up to t of the C available channels. We assume no shared secret keys or third-party infrastructure. The running time of our protocol depends on the gap between C and t: when the number of channels C =Omega(t^2), the running time is linear; when only C = t+1 channels are available, the running time is exponential. We prove that exponential-time is unavoidable in the latter case. At the core of our protocol lies a combinatorial function, possibly of independent interest, described for the first time in this paper: the multi-selector. A multi-selector generates a sequence of channel assignments for each device such that every sufficiently large subset of devices is partitioned onto distinct channels by at least one of these assignments.

An efficient heuristic algorithm for channel assignment problem in cellular radio networks

Abstract: This paper presents an efficient heuristic algorithm for the channel assignment problem in cellular radio networks. The task is to find channel assignment with minimum frequency bandwidth necessary to satisfy given demands from different nodes in a cellular network. At the same time the interference among calls within the same cell and from different neighboring cells are to be avoided, where interference is specified as the minimum frequency distance to be maintained between channels assigned to a pair of nodes. The simplest version of this problem, where only cochannel interferences are considered, is NP-complete. The proposed algorithm could generate a population of random valid solutions of the problem very fast. The best among them is the optimum or very near to optimum solution. For all problems with known optimal solutions, the algorithm could find them. A statistical estimation of the performance of the proposed algorithm is done. Comparison with other methods show that our algorithm works better than the algorithms that we have investigated.

A trunked radio frequency communication system for accommodating both frequency and time division based rf communications

Abstract: In a trunked radio communications system, apparatus and methods are provided for transparently updating existing frequency division multiple access (FDMA) communications facilities to accommodate time division multiple access (TDMA) communications TDMA channels are added to existing FDMA sites on an individual basis to increase spectral efficiency and capacity while still being compatible with existing FDMA equipment and protocols For example, the existing FDMA control channel and protocols are used by dual mode sites and dual mode radios A dual mode radio transceiver selectively participates in trunked radio communications in either an FDMA mode and in a TDMA mode Each dual mode radio includes a memory for storing a mode identifier identifying each channel as an FDMA or a TDMA working channel When a channel assignment is made, the dual mode radio determines from that channel mode identifier stored in memory whether to operate in the FDMA or TDMA mode for that particular communication Moreover, dual mode radios expedite synchronization to a TDMA working channel (time slot) using a timing relationship established between the FDMA control channel and the TDMA working channels In the context of multiple site, trunked radio communications, the present invention provides for interoperability between sites and radios which have TDMA communications capabilities and sites and radios which have only FDMA capabilities