Various wireless networks scenarios involve dissemination of large amounts of control information. This limits the channel resources available for transmission of the user data. This problem is especially crucial in dense networks, sensor networks, and high-mobility networks (e.g., networks of vehicles and drones). Several methods for dissemination of control information are known. This study is focused on the promising method called differential update. The idea behind it is that control messages sent by stations should contain only the information modified since the transmission of the previous message. An analytical model of this method has been developed. It allows one to estimate the average amount of transmitted control information and the reliability and promptness of its delivery to neighboring stations. An algorithm for adaptive tuning of parameters of the differential update method has been developed on the basis of this model. Simulation results obtained with NS-3 simulator demonstrate that the proposed algorithm minimizes the amount of sent control information while satisfying the set of requirements on reliability and promptness of its delivery.
An increase in the network capacity is a requirement for modern LTE cellular networks. A part of the RF spectrum that is available for transmission is among the most important limiting factors. Such a problem can be solved in the LTE networks using unlicensed bands that are employed in alternative (e.g., Wi-Fi) technologies with the aid of a new LTE-LAA technology. In this work, we perform a comparative analysis of the channel access procedures for unlicensed bands that are described in the Wi-Fi standard and LTE-LAA specification and discuss open problems of coexisting technologies.
The effect of the mutual positions of hysteresises in the access control of the wireless broadband network with different thresholds with respect to access enable and disable to the network resources with allowance for the service class is numerically analyzed. Three variants of the mutual positions of hysteresises in the access control of three flows with different requirements on the level of service are considered. The efficiencies of the additional processing of the low_class requests with unnormalized losses are calculated with allowance for diurnal variations in the network load.
Statistical decoders are one of the most robust decoders for positional modulations like FSK and PPM. As we show in this work they are applicable to any (unknown) channels that have non-zero distance between received signals. This makes it possible to use statistical decoders in NOMA random access communication systems with bad Channel State Information. In this work we consider the problem of data transmission over unknown memoryless channels. To the author's knowledge this problem was not studied in literature till now. We propose repetition Kautz-Singleton codes and statistical decoders as a solution to this problem. To estimate the performance of the proposed solution we propose a lower and an upper asymptotic bounds on error rate for statistical decoder. These bounds are evaluated for Kolmogorov-Smirnov goodness-of-fit criteria and compared to a computer simulation. The lower bound seems to be close to the simulation result. The upper bound is not that close to the simulation result but it still holds. To the author's knowledge this is the first technique to derive bounds on error rate for any distance-based statistical decoder. These bounds for the Kolmogorov-Smirnov goodness-of-fit criterion also show that the error rate should be inversely proportional to the square root of code distance. Other goodness-of-fit criteria might yield asymptotically better results.
At the moment, for the equalization of reads histogram, which derived from the treatment of the transcriptome of diﬀerent individuals, it is suggested to use a negative binomial distribution. In this paper we analyze the “physical” basis of a broadening of Poisson distribution, and conclude that the true form of the distribution is really compound Poisson distribution (a special case of which is the negative binomial distribution), but the true choice is another special case of this distribution, i.e. n-times convolution (n is a random variable with Poisson distribution) of random variables with the exponential (not logarithmical) distribution. It is shown that a distribution of gene expression intensity in a group of individuals calculated from the published data is described better by the convolution of exponential functions.
NR-U is a technology that allows fifth generation cellular networks to utilize unlicensed frequency bands, in particular, the 5 GHz band. In order to increase throughput, an NR-U base station (gNB) can operate at the same time in several frequency channels located within this band. However, a gNB can not always simultaneously transmit in one channel and perform the channel access procedure in another channel because of the out-of-band emission problem, which leads to channel underutilization. As a result, throughput of NR-U networks can highly depend on the out-of-band emission level. In this paper, using simulation, the impact of out-of-band emissions on NR-U performance is studied with all channel access methods defined in the NR-U specification. It is shown that out-of-band emission level affects the choice of the channel access method which is optimal in terms of throughput. It is also shown that out-of-band emissions do not always have a negative impact on NR-U performance, and sometimes they allow to achieve more than 30% throughput gain.
In the paper, we consider the score value of some functional of conditionally normally distributed random variables, which is linked to the problem of the sequential hypothesis testing. It is ascertained that the evaluation was limited in growth, which is responsible for setting the average length of observations.
Methods for constructing a mapping of the elements of a multiplicative group of a Galois field onto a symmetric group of permutation matrices are proposed. A technique minimizing the order of the symmetric group is suggested. The results are used for constructing an ensemble of low-density parity-check codes. The obtained code constructions are tested on an iterative belief propagation (sum-product) decoding algorithm on transmission of a code word through a binary channel with an additive Gaussian white noise.
In this paper, we consider a vector disjunctive channel in which users transmit some binary vectors of length L. We estimate the capacity of this channel and derive a lower bound on this value. In addition, the lower bound is calculated both for the case of the Bernoulli distribution and for an arbitrary distribution for the case when L = 2. It is shown numerically that for L = 2 and the multiplicity of the collision t = 1, the Bernoulli distribution is optimal, i.e., it maximizes the throughput of the vector disjunctive channel.