Experimentation on Co-channel Interference Effects of RIS-Assisted Networks in Overlapping Coverage Areas

Call Admission Control (CAC) is one of the most important parts in Radio Resource Management of the wireless networks and it has a huge impact on the quality of service (QoS).Traditional CAC strategies focus on increasing the radio resource utility by decreasing the service blocking probabilities. In this paper, a new CAC scheme based on game theory is introduced to analyze the conflicts and rewards for different network operators. The game theoretic based CAC scheme contains two parts, utility function computation and a non-cooperative game between two networks to maximize their rewards. The proposed framework is preliminary and its objective is investigate the possibility that networks should be able to autonomously define policies for different parts of a coverage area depending on the priority of users and their requirements. In this approach, the two simulated WiMAX networks compete with each other for traffic units in overlapping coverage area and maximize their rewards. The proposed scheme is illustrated with the help of an example in which most of the traffic units lie close to one network as compared to the other network. Future work will present results of simulation studies for more detailed experiments.

A new way to manage users having different mobility characteristics (slow and fast users) in a two layer cellular system, through the use of the techniques of overlapping coverage and channel rearrangement, is provided. Overlapping coverage areas of nearby base stations arise in cellular communications systems, especially in small cell high-capacity microcellular configurations. With overlap, some users may have access to channels at more that one base station. This enhanced access can be used to improve the teletraffic performance characteristics. Channel rearrangements are used to benefit users who are in the range of only one base station. An analytical model for teletraffic performance is developed. Performance measures are derived and discussed.

This research work is based on the location prediction of wireless nodes with the terrains/clutters considerations. Multi-condition Bayesian decision theory is applied for precision in selected locations. Currecnt research is the continution of our previous research work in which twelve terrains were proposed based on the atmospharic atteunation. In the first phase of paper, basic parameters such as receive signal strength and available signal strength are calculated by using terrain/clutter considerations. Secondly, geomatric approach is used to calculate angle of arrival. Finally, multi-condition bayesian decision theory is used to precise the calculated results. Three posterior probabilities, the angle error rate (e), overlapping coverage area (Ω) and the terrains/clutters error rate (Ć) are used with the Bayesian decision theory for the most probable location of wireless node. Results show that 60%- 80% accuracy could be achived if proper terrain defination and multi-condition bayesian decision theory is followed.

We consider caching in cellular networks in which each base station is equipped with a cache that can store a limited number of files. The popularity of the files is known and the goal is to place files in the caches such that the probability that a user at an arbitrary location in the plane will find the file that she requires in one of the covering caches is maximized. We develop distributed asynchronous algorithms for deciding which contents to store in which cache. Such cooperative algorithms require communication only between caches with overlapping coverage areas and can operate in asynchronous manner. The development of the algorithms is principally based on an observation that the problem can be viewed as a potential game. Our basic algorithm is derived from the best response dynamics. We demonstrate that the complexity of each best response step is independent of the number of files, linear in the cache capacity and linear in the maximum number of base stations that cover a certain area. Then, we show that the overall algorithm complexity for a discrete cache placement is polynomial in both network size and catalog size. In practical examples, the algorithm converges in just a few iterations. Also, in most cases of interest, the basic algorithm finds the best Nash equilibrium corresponding to the global optimum. We provide two extensions of our basic algorithm based on stochastic and deterministic simulated annealing which find the global optimum. Finally, we demonstrate the hit probability evolution on real and synthetic networks numerically and show that our distributed caching algorithm performs significantly better than storing the most popular content, probabilistic content placement policy and Multi-LRU caching policies.

Recent demand for capacity increase in mobile communications urges the development of both multiple- input multiple-output (MIMO) and small cells. However, overlapping coverage areas between neighboring small cells results in interference-limited networks, where the capacity of the network is severely degraded without superior intercell interference management (IIM) techniques. As one of the superior IIM techniques, the power control intercell interference coordination (ICIC) optimizes downlink transmit powers in the network. This paper proposes an IIM scheme consisting of both neural networks (NNs) power control on the transmitter side and interference cancellation (IC) on the receiver side. Computer simulations examine networks of MIMO systems with the power optimization using some ICIC algorithms: NN, the greedy search, the belief propagation (BP), and the maximum power, combined with IC on the receiver side. In addition, the deep learning, a breakthrough technique for NN with multi-layer structures, is also applied to mobile communications. The results show that the performance of NN is very close to that of the greedy search and superior to that of BP. Complexity of NN is much less than that of BP, and thus NN is suitable for IIM. It is also demonstrated that employing IC provides high capacity gain.

Mobile data offloading is an emerging technology to alleviate cellular network congestion and improve user service quality. In this paper, we investigate the economics of mobile data offloading through access points (APs) deployed by small cell service providers (SSPs), implementing uniform volume prices for all the mobile users (MUs) in each SSP's coverage including the overlapping area. In particular, we consider a data offloading game with a single mobile network operator (MNO) and two SSPs with overlapping coverage areas, where each SSP announces a uniform price for serving the cellular traffic within its coverage, and the MNO determines the traffic volumes to offload. We show that there is no pure Nash equilibrium (PNE) under such price competition, and determine the corresponding mixed strategy Nash equilibrium (MNE) using price randomization. As a practical solution, we propose a simple one shot auction mechanism that is easy to implement and has PNEs which is payoff equivalent with the MNE under price competition. We believe that this simple mechanism due to its simplicity of determining the equilibrium prices could be used in the negotiation between the SSPs and the MNO to determine the average service prices. Finally, we study the strategic topological infrastructure placement problem using a 1-dimension (1D, linear) user traffic flow model and a 2-dimension (2D) user traffic flow model when SSPs compete assuming uniform price competition as above. We show that the first mover in the placement problem will deploy its APs to cover more than half of the total flow volume and has an advantage to obtain a higher equilibrium payoff.

The regulatory framework for secondary utilization of TV white spaces (TVWS) is well underway in the United Kingdom, while important steps in this direction are taken within the European Union and elsewhere. Mobile network operators are interested in the use of TVWS for cellular extension and rural access, where TVWS is seen as a significant new opportunity for operators to provide new wireless services. The government's plan to close the digital divide between the urban and rural communities has motivated the efforts to develop Wi-Fi like operation in TVWS for better coverage in rural areas. The IEEE currently has a working group developing 802.11af amendment which will allow for WLAN operations in the TVWS. This paper presents a quantitative analysis of downlink throughput performance of IEEE802.11af, also known as White-Fi in a rural environment while taking into account realistic modelling of TV channel availability, wireless channel, AP density, and the effect of co-channel interference caused by secondary APs and DVB-T transmitters. The paper shows that the low operating frequency of White-Fi offers a wide coverage in a rural environment, where there is limited cellular coverage due to the cost-inefficiency of base stations deployment. The presented results also show that there are more available TVWS channels and less co-channel interferers in a rural environment, resulting in a significant throughput performance even in high mobility if suitable channel estimation is considered, making it ideal for vehicular communications with White-Fi.

Land mobile radio channels are modeled as fading dispersive channels, because of the multipath propagation and the randomly changing medium characteristics. Many types of impairments are observed on these channels such as multipath spread (or delay spread), fading, Doppler spread, nonlinear distortion, frequency offset, phase jitter, impulse noise, thermal noise, and co-channel and adjacent channel interference arising from spectrum sharing. This chapter concentrates on the effects of delay spread, fading, Doppler spread, thermal noise, and co-channel interference. Delay spread causes interference between adjacent symbols, known as intersymbol interference (ISI), a large Doppler spread indicates rapid channel variations and necessitates a fast convergent algorithm when an adaptive receiver is employed, and fading results in a very low received signal-to-noise ratio or signal-to-interference ratio when the channel exhibits a deep fade.

The provision of mobile cloud service calls for a wireless access infrastructure that offers high bandwidth to mobile users. Among all enabling technologies, wireless mesh networks (WMNs) have the advantage of low deployment cost and widely available user equipments. To provide more bandwidth, access points in WMNs are commonly equipped with multiple wireless interfaces (radios) that can operate on multiple non-overlapping channels in parallel. The objective of channel assignments in a multi-channel, multi-radio MWN is to reduce co-channel interference experienced by links so as to increase network capacity while maintaining network connectivity. Prior studies addressing this issue majorly considered effects of co-channel interference at the link layer. In this study, the authors consider co-channel interference at the physical layer. Furthermore, most existing methods are based on heuristic or game theory. This study applies simulated annealing technique to the channel allocation problem. The objective function for this approach is defined as the total signal-to-interference radio (SIR) experienced by each link. To maintain network connectivity, the proposed approach limits the set of assigned channels for each radio. Experimental results show that, compared with traditional heuristic-based and game-theoretic approaches, the proposed simulated annealing algorithm results in more operative links.

This paper analyzes the outage probability of multi-branch dual-hop decode-and-forward (DF) cooperative relaying systems over non-identical Nakagami/Nakagami fading channels. The paper derives an exact closed-form expression for the outage probability with maximum ratio combining considering both the effect of co-channel interference (CCI) and addictive white Gaussian noise. The results of this paper show that a DF cooperative relaying system is more vulnerable to noise than interference for low and moderate SINR, whereas it is more susceptible to interference than noise for high SINR and high diversity order. Moreover, this paper shows that the robustness of the destination against CCI is more important than that of the relay. The results of this paper are verified by Monte Carlo simulations.

This study investigates the impact of co-channel interference on two-way untrustworthy relay selection over Rayleigh fading environment. The investigation considers that two source terminals make information exchange over J number of full-duplex based amplify-and-forward bi-directional untrustworthy relay in the presence of co-channel interference. In addition, limited number of friendly jammers generate artificial interference/noise signals to mitigate information leakage. So as to minimize the system overhead and also enhancing secrecy performance, the relay selection is made by means of max–min criteria, which is based on maximizing the minimum secrecy rate over the relay terminals. The system model fundamental performance limits are measured by means of secrecy outage probability, secrecy achievable sum rate, intercept probability, and secrecy throughput analysis metrics. According to Monte-Carlo based simulations and numerical results, the max–min based selection strategy achieves cooperative diversity order, which is equal to total number of possible paths, in high signal-to-noise ratio regimes. Results also reveal that the co-channel interference dominates the process of the information exchange and degrades the achievable cooperative diversity order from J to 0 and leads system coding gain losses on free-interference cases in high signal-to-noise ratio regimes.

In addition to diversity, forward error correction (FEC) coding is a well-known method that can be used to improve the performance of communication on wireless fading channels. In this paper, we investigate the performance of combined diversity and FEC coding strategies. For block coding to be effective, bit errors in each code word should be independent. To render the channel memoryless, perfect bit interleaving is assumed. That is, bit errors in the code word are assumed to be independent. In this paper, we analyze the performance of M-ary differential phase shift keying (MDPSK) on frequency-selective Rayleigh fading channels using two branch postdetection equal gain (EG) combining. Both the effects of correlation between the two diversity branches and the effects of cochannel interference on the BER performance are investigated. The interferers are assumed to be MDPSK modulated signals with same symbol rate as that of the desired signal, but with random symbol timing offsets relative to the desired signal. The cochannel interference contribution is represented by a Gaussian noise whose mean and variance are equal to the mean and variance of the sum of the interfering signals.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

In recent years, due to the rapid convergence of multimedia services, Internet and wireless communications, there has been a growing trend of heterogeneity (in terms of channel bandwidths, mobility levels of terminals, end-user quality-of-service (QoS) requirements) for emerging integrated wired/wireless networks. Moreover, in nowadays systems, a multitude of users coexists within the same network, each of them with his own QoS requirement and bandwidth availability. In this framework, embedded source coding allowing partial decoding at various resolution is an appealing technique for multimedia transmissions. This dissertation includes my PhD research, mainly devoted to the study of embedded multimedia bitstreams in heterogenous networks, developed at the University of Bologna, advised by Prof. O. Andrisano and Prof. A. Conti, and at the University of California, San Diego (UCSD), where I spent eighteen months as a visiting scholar, advised by Prof. L. B. Milstein and Prof. P. C. Cosman. In order to improve the multimedia transmission quality over wireless channels, joint source and channel coding optimization is investigated in a 2D time-frequency resource block for an OFDM system. We show that knowing the order of diversity in time and/or frequency domain can assist image (video) coding in selecting optimal channel code rates (source and channel code rates). Then, adaptive modulation techniques, aimed at maximizing the spectral efficiency, are investigated as another possible solution for improving multimedia transmissions. For both slow and fast adaptive modulations, the effects of imperfect channel estimation errors are evaluated, showing that the fast technique, optimal in ideal systems, might be outperformed by the slow adaptive modulation, when a real test case is considered. Finally, the effects of co-channel interference and approximated bit error probability (BEP) are evaluated in adaptive modulation techniques, providing new decision regions concepts, and showing how the widely used BEP approximations lead to a substantial loss in the overall performance.

Single-carrier frequency domain adaptive antenna array for uplink multi-user MIMO transmission in a cellular system

A unified approach is presented for evaluation of the error probabilities of a class of digital communications systems in additive noise and interference. This class of systems includes coherent systems such as M -ary amplitude-shift keying (ASK), M -ary phase-shift keying (PSK), and M -ary amplitude-and-phase keying (APK); it also includes differential coherent systems such as binary differential PSK (DPSK). The noise is not necessarily Gaussian. The interference can be intersymbol interference, co-channel interference, adjacent-channel interference, any of their linear combinations, or intermodulation prodducts at the output of some nonlinear device. This approach essentially expands the characteristic function of the interferences into a power series so that the desired error probability can be evaluated as the sum of terms representing perturbations around the error probability due to additive noise alone. Bounds on three kinds of truncation errors, which are simple and applicable to all aforementioned digital systems, are obtained. As a result, any desired accuracy in the evaluation of the error probabilities can be achieved with this approach. In the special case in which the noise is Gaussian, explicit bounds on truncation errors are also obtained. Examples are given to illustrate how the unified analysis can be applied to evaluate the error probabilities of various digital systems. More specifically, the combined effects of Gaussian noise, intersymbol interference, and co-channel interference on the error performance of M -ary coherent PSK and APK (MCPSK and MCAPK) systems are computed. The probability of error of a binary DPSK (BDPSK) system in the presence of Gaussian noise and intersymbol interference is analyzed. The intermodulation products at the output of a hardlimiter are also determined.