Slotted Multiple Access Research Articles

An analytical model for optimal spectrum leasing under constraints of quality of service in CRNs

Cognitive radio improves spectrum efficiency and mitigates spectrum scarcity by allowing cognitive users to opportunistically access idle chunks of the spectrum owned by licensed users. In long-term spectrum leasing markets, secondary network operators make a decision about how much spectrum is optimal to fulfill their users’ data transmission requirements. We study this optimization problem in multiple channel scenarios. Under the constrains of expected user admission rate and quality of service, we model the secondary network into a dynamic data transportation system. In this system, the spectrum accesses of both primary users and secondary users are in accordance with stochastic processes, respectively. The main metrics of quality of service we are concerned with include user admission rate, average transmission delay and stability of the delay. To quantify the relationship between spectrum provisioning and quality of service, we propose an approximate analytical model. We use the model to estimate the lower and upper bounds of the optimal amount of the spectrum. The distance between the bounds is relatively narrow. In addition, we design a simple algorithm to compute the optimum by using the bounds. We conduct numerical simulations on a slotted multiple channel dynamic spectrum access network model. Simulation results demonstrate the preciseness of the proposed model. Our work sheds light on the design of game and auction based dynamic spectrum sharing mechanisms in cognitive radio networks.

A Novel Backoff Algorithm with QoS Support in Heterogeneous Wireless Networks

The main objective of the future networks is to provide users with always best connectivity through available different access networks. Wireless convergence has emerged as a multidimensional concept that combines networks, applications, user interfaces and management, which aimed at supporting voice, data and multimedia over IP-based networks. In this paper, we model the end-to-end quality of service (QoS) provisioning mechanisms in the wireless local area network (WLAN) and worldwide interoperability for microwave access networks (WiMAX) interworking network. For the end to end QoS guaranteed service, we make changes to multiple access protocol. The media access control (MAC) analysis using hybrid protocol based on virtual slot multiple access (VSMA) with a novel backoff mechanism is extended to the heterogeneous networks and its throughput and delay characteristics are analyzed. By the simulation results, our proposed protocol can provide the low end to end delay and improved throughput for different traffics, even though the traffic load in the network increases. Especially, the end-to-end delay of the IP based voice is smaller when the QoS parameter mappings are applied to the interworking network.

MAC Sub-Layer Analysis with Channel Estimation in Broadband Power Line Communication

Broadband power line communication (BPLC) gained a lot of interest because of low cost and high performance communication network in access area. In this paper physical (PHY) layer and medium access control (MAC) sub-layer of BPLC are considered. Furthermore, effects of bit error rate (BER) are analyzed in MAC sub-layer. Powerful turbo convolutional code (TCC) and wideband orthogonal frequency division multiplexing (OFDM) are used in PHY layer. Carrier sense multiple access (CSMA) and virtual slot multiple access (VSMA) are taken into consideration in MAC sub-layer. Multilayered perceptrons neural network with backpropagation (BP) learning channel estimator algorithm compare to classic algorithm in for channel estimating. The simulation results show that the proposed neural network estimation decreases bit error rate then in MAC sub-layer throughput increases and access delay is decreased.

Prioritized slotted multiple access protocols for bank LANs

AbstractFour classes of traffic are present in a bank communication system: Alarm, BSC, SNA and IP traffic, with each class of traffic having different priority requirements. In this paper, a prioritized multiple access protocol is introduced which is capable of handling the above priority classes. The proposed protocol makes use of learning automata in order to dynamically assign the available bandwidth to the priority classes. In this way, it is capable of being adapted to the traffic conditions. The proposed protocol, is applicable to a broad range of prioritized LANs, as it can be easily extended to support multiple classes of traffic. Copyright © 2003 John Wiley & Sons, Ltd.

A new analyzing approach to modeling slotted multiple access systems

In this paper, the analyzing approaches proposed by Zhao Dongfeng, et al.(1997) have been extensively studied. The average cyclic times of the slotted multiple access systems are analyzed by using the average cycle method. Analytic formulae for mean values of a successful period and a colliding period and an idle period are derived. The upper bounds of the system throughput with capture effect and collision resolution are provided. Finally, the simulation results of the slotted multiple access channels are given.

The capture effect in multiaccess communications-the Rayleigh and landmobile satellite channels

The capture phenomenon and its consequences in nonbitsynchronous mobile packet radio networks for binary phase-shift-keying (BPSK) and differential phase-shift-keying modulation are investigated. Exact values of the bit error probability for given signal-to-noise ratios of colliding BPSK signals are derived. Packet error rates, which are needed for analysis of slotted random multiple access methods, are obtained by simulation. Two kinds of mobile radio channels are considered: the Rayleigh fading channel and the land mobile satellite channel. In the latter, because of shadowing, the probability that one of several colliding data packets is correctly received can be on the same order as the probability that a single packet that is not experiencing a collision is correctly received. The influence of Reed-Solomon codes on packet error probabilities is also studied. A slotted ALOHA system using the land mobile satellite channel is analyzed. It is found that with significant shadowing, the overall system throughput may reach the point-to-point throughput. Also, the code rate cannot be optimized in a straightforward manner by assuming one single transmission at a time. >

Simulation of slotted random multiple access protocol

A Slotted Random Multiple Access protocol which is an extension of Random Multiple Access protocol is proposed. Protocol performance is evaluated using simulation, giving throughput, delay and stability curves. Comparison with other protocols shows that at high traffic rates the Slotted RMA is superior to other protocols.

Queueing analysis of buffered slotted multiple access protocols

Much of the literature on the performance evaluation of multiple access protocols has assumed a buffer capacity of one unit. This assumption is not realistic. In practice the buffer capacities used are larger than one unit in order to reduce the probability of packet rejection. This is more crucial for multiple access protocols, which allow moderate to high values of the expected throughput (URN, Random TDMA etc.). In this paper, a model appropriate for the analysis of buffered slotted multiple access schemes is proposed. The method can be applied to several multiple access protocols such as the URN protocol, the ALOHA protocol, Random TDMA etc. The cases of infinite and finite buffer capacity are examined separately but under the same basic assumptions. The analysis is based on the assumption that each user process can be modelled as an M/G/1 queueing system. The proposed method requires a small amount of computation and is characterized by a high speed, a fact that simplifies the buffer's design as well. The solution obtained is extremely accurate and exhibits excellent agreement with simulation results, which corroborate the accuracy of the model. The special case when the buffer capacity is equal to 1 is examined. In that case, the present approach also allows for computation of the packet delay distribution.