Distributed Dynamic Channel Assignment Research Articles

A Petri-Net-Based Automated Distributed Dynamic Channel Assignment for Cellular Network

In this paper, we propose a Petri-net (PN)-based automated distributed dynamic channel assignment (DDCA) method for the cellular network. We view DDCA as a discrete event system (DES) and propose a PN to model the automated DDCA. The spontaneous handshaking mechanism in the proposed PN can resolve the hard constraint of the cellular network so that no two cells within the channel reuse distance can use the same channel. Instead of the commonly adopted packing and resonance conditions for channel assignment and reassignment, we propose available channel-based channel-selection and channel-reassignment schemes. We rigorously prove the adequacy of the proposed PN and the satisfaction of hard constraint. We also test the proposed PN-based automated DDCA method using numerous test cases. The test results show that our method outperforms the comparing methods in terms of blocking probability.

Distributed dynamic channel assignment in TDMA mobile communication systems

Dynamic channel assignment (DCA) has been a topic of intense research for many years, and a variety of DCA algorithms have been proposed. Nonetheless, some important issues have been neglected because of the complexity involved in their study. In particular, the impact of user motion on the performance of DCA systems has not received enough attention. In this paper, we quantify the impact of motion on the capacity and cost-in terms of average number of reassignments per call-of a variety of representative distributed fixed-power DCA algorithms. A novel adaptive algorithm especially suited for mobility environments is proposed, which achieves high capacity while controlling the reassignment rate. We also prove that most of this capacity can be effectively realized with a reduced number of radio transceivers per base station. Finally, we evaluate the degradation associated with the use of estimates of local-mean signal and interference levels-obtained by averaging instantaneous measurements-instead of the actual local-mean values.

Reducing call dropping in distributed dynamic channel assignment algorithms by incorporating power control in wireless ad hoc networks

Methods of substantially reducing call dropping in networks which use distributed dynamic channel assignment (DDCA) schemes are discussed. Interference and received power thresholds coupled with power control are used to maintain performance, without the need for intra-cell handoffs. It is shown that the schemes reduce call dropping and increase capacity compared to those using fixed transmitter power. The schemes are developed with the aid of mathematical analysis and a pictorial model. Results are presented which show that call dropping may be virtually eliminated in shadowing environments with the median transmitter power being reduced by 15 dB. The various call dropping mechanisms are discussed, and it is suggested that the residual level of call dropping is principally a result of multiple additional call arrivals close to an active link. Methods to make further reductions in the call dropping probability are also proposed.

A distributed dynamic channel assignment method for a mixture of narrowband and broadband traffic in a cellular system

This paper proposes an autonomous distributed dynamic channel assignment method, considering a mixture of narrowband and broadband traffic processing in a multicarrier TDMA mobile communication system. As the first step, narrowband and broadband calls are considered, and the system in which the calls share the carrier [carrier-sharing (CS) method], and the system in which the calls use separate carriers [carrier partitioning (CP) method], are compared. For each method, a mathematical model is proposed for the blocking probability analysis in the dynamic channel assignment, based on the steady-state probability. Using the models, the range for which the CS method exhibits a better performance than the CP method is specified. A problem in the dynamic channel assignment in the CS method is that the transmission quality of the broadband call may be degraded by interference from a narrowband call. In order to overcome such a problem, a method is proposed where the suppression of the leftovers of nonavailable channels for assignment, the multicarrier modulation using frequency hopping, the reallocation connection of calls, the variable-rate transmission connection, and the retry-type hand-off are combined. It is verified by computer simulation that the proposed method exhibits a performance which is better than that of the conventional method. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(11): 85–94, 2000

A New Distributed Dynamic Channel Assignment Strategy in a Cellular Mobile Communication Network

A distributed dynamic channel assignment (DDCA)plays an important role in a microcellular mobilecommunication network. This paper proposes a new DDCAscheme based on channel priority (PDCA). This new strategy uses the cochannel interference andchannel reuse frequency to define the channel priority.The strategy improves performance of the forced calltermination rate and interference rate applied to multimedia traffic. Simulation results showthat the proposed PDCA strategy significantly improvesthe forced call termination rate and interference ratewhile keeping the blocking rate at an acceptable level.

Handoff prioritisation with implicit hannel reservation in distributed dynamic channel ssignment algorithms

A new distributed dynamic channel assignment scheme with implicit channel reservation for handoff prioritisation is proposed. This scheme reduces the degree of computation and communications among base stations required for channel reservation and achieves a capacity similar to that of the maximum packing algorithm. For 40 total channels, the proposed algorithm achieves a 116% capacity increase relative to the non-prioritised fixed channel assignment (FCA) scheme and 93% relative to FCA with optimum channel reservation.

An aggressive dynamic channel assignment strategy for a microcellular environment

A new aggressive distributed dynamic channel assignment strategy for microcellular telephone networks is proposed. Channels are assigned in carrier groups, where carriers are acquired and released according to a carrier acquisition and release criterion. Whenever a call is in jeopardy of a forced termination, or handoff failure, the serving cell may force a cell in the surrounding neighborhood to relinquish a carrier to service the call. This aggressive strategy actually improves the arrangement of carriers throughout the network. Simulations show this strategy to decrease the probability of forced termination at the expense of a slight increase in the probability of new call blocking over most ranges of offered traffic. Improvements are shown for two different channel selection criteria: one using simple carrier orderings, and a more complex one called dynamic resource acquisition.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>