Approaches to an occupancy problem resulting from MFSK systems with diversity and majority vote

[[abstract]]This paper is concerned with a combinatorial probability problem resulting from an M-ary frequency shift keying (MFSK) system with diversity transmissions and majority vote. This problem is equivalent to an occupancy problem concerning the probability that m boxes each contain exactly r balls and each of the remaining n−m boxes has less than r balls resulting from distributing k balls into n boxes. Two approaches based on recursive algorithms to the problem are derived and their computational efficiencies are compared

A recursive solution to an occupancy problem resulting from TDM radio communication application

[[abstract]]In this paper we treat an occupancy problem: the probability that m out of n boxes each have exactly one ball resulting from distributing k balls into n boxes. The solution to this problem is given by a set of recursive expressions. By translating these formulae into a computer program, one can easily obtain the numerical results

On the performance of frequency-hopped spread-spectrum systems utilizing near-orthogonal hopping patterns

[[abstract]]A simple near-orthogonal code is used as frequency-hopping patterns for the frequency-hopped multiple access systems. Extended RS code is used as channel coding to deplete the effects of hits from simultaneous users. Packet error probability and channel throughput for the system utilizing the near-orthogonal code are evaluated and compared to the corresponding values obtained from the system utilizing random patterns. Results show that the former can provide substantial improvement over the latter. In our illustrated examples, we also show that under the constraint of packet error probability P_E≦10^, the maximum achievable number of users with most (n, k) RS codes of interest is less than the number of distinct codewords in the near-orthogonal code. Thus, the number of codewords of the near-orthogonal code is large enough to support the practical application

Performance analysis of non-collision packet reservation multiple access protocol for wireless communications

[[abstract]]In this paper we investigate the non-collision packet reservation multiple access (NC-PRMA) protocol, which is a variation of the PRMA protocol proposed previously. We evaluate the NC-PRMA protocol and compare its performance to PRMA. Performance measures used are channel throughput, mean access delay, and packet dropping probability. Analysis and simulation results show that NC-PRMA outperforms PRMA in general and achieves the same user capacity as PRMA with a perfect capture mechanism

Throughput analysis of packet reservation multiple access protocol for wireless communications

[[abstract]]封包預約式多重介入規約（PRMA）為一新提議之無線通信規約。此規約利用限制處於靜音狀態的使用者的傳送，以提高系統容量。在文獻上此規約已被分析，此分析是利用所謂的平衡點分析（EPA）方法，然而此種方法在負載高的時候可能產生多個平衡點，使得真正的系統狀態無法被唯一決定。因此我們利用二維馬可夫鏈（MarkovChain）的模型，來分析此規約的流通量（Throughput），在狀態轉變機率值求出之後，系統的平衡機率即可以決定，據此我們可以算出流通量。 It has been shown that the packet reservation multiple access (PRMA) protocol, originally proposedby D．J. Goodman et al. for wireless communications, can improve the user capacity by preventing usersfrom using resources during their silent gaps. In the literature, the protocol has been studied using themethod of equilibrium point analysis (EPA)．However, this method may generate multiple equilibriumpoints in high load conditions, so that the exact behavior of the system cannot be determined uniquely.Thus, we introduce a two-dimensional Markov chain model to analyze in an approximate manner the PRMAprotocol. After the steady-state probabilities are found, the channel throughput can be uniquely determined

Integration of voice/data services over PACS systems using movable boundary slot allocation scheme

[[abstract]]The integration of voice and data services over PACS systems using a movable boundary scheme is studied. First, we use the theory of discrete-time Markov chain to analyse the system; then, an approximate analysis using the continuous-time Markov chain model is conducted. For the initial access of voice calls we consider two distinct schemes: at most one idle slot being marked available, and all the idle slots being marked available. Numerical results show that the performance difference for voice calls between both schemes is trivial, but the former scheme offers a performance advantage for data calls over the latter scheme. Besides, the performance obtained by the continuous-time Markov model is very close to that obtained by the discrete-time Markov model. This finding suggests the effectiveness of the usage of the continuous-time Markov model, which can dramatically simplify the analysis

Performance of FH/MFSK systems for speech with activity detector over Rayleigh fading channels

[[abstract]]This paper presents the performance of FH/MFSK systems, which exploit silent gaps in speech to accommodate more users, over Rayleigh fading channels. Two kinds of receivers are considered: one uses a threshold on the received signal strength to declare whether the signals were present or not, and the other is assumed to have perfect transmitter-state information obtained from using additional bandwidth. Results show that, if the codeword dropping and codeword error are assumed to be equally costly, the former can achieve slightly better performance than the latter in the decoding error probability. This finding suggests that, for the system to exploit silent gaps in speech, it is advantageous for the receiver to use a threshold to declare whether signals were present or not instead of relying on the transmitter-state information

A secure DSDV routing protocol for ad hoc mobile networks

[[abstract]]This paper presents a secure destination-sequenced distance-vector routing protocol (SDSDV) for ad hoc mobile wireless networks. The proposed protocol is based on the regular DSDV protocol. Within SDSDV, each node maintains two one-way hash chains about each node in the network. Two additional fields, which we call AL (alteration) field and AC (accumulation) field, are added to each entry of the update packets to carry the hash values. With proper use of the elements of the hash chains, the sequence number and the metric values on a route can be protected from being arbitrarily tampered. In comparison with the secure efficient distance vector (SEAD) protocol previously proposed in the literature provides only lower bound protection on the metrics, SDSDV can provide complete protection. © 2009 IEEE