Signal Interference Plus Noise Ratio Research Articles

Connectivity Analysis with Co-Channel Interference for Urban Vehicular Ad Hoc Networks

In urban vehicular ad hoc networks (VANETs), the complex channel environment and co-channel interference resulted in the uncertain delay of inter-vehicle packet transmission, which causes serious delay jitter. Connectivity is proposed as a key metric to describe this uncertainty. However, existing works lack a discussion of inter-vehicle connectivity in urban VANETs, particularly with regards to the process of transmitting packets between vehicles. In this paper, we analyze the connectivity probability of urban VANETs under co-channel interference with both complete and incomplete information. When the information is complete, we model the time-varying nature of co-channel interference and channel fading as delay jitter and analyze inter-vehicle connectivity in a time-varying environment. Then, when complete information is unavailable, we estimate the probability distribution of co-channel interference by combining the distribution of multiple parameters with the free space propagation model (Friss) model and Nakagami-m fading model. The expression for the connectivity performance of vehicle-to-vehicle (V2V) links is derived from the signal interference plus noise ratio (SINR) of the destination V2V link. Finally, we analyze the implications of various factors on connectivity, such as the transmit power of the signal, the arrival rate of packets, the number of channels and vehicles, and the distance between the transmitting vehicle and the receiving vehicle. The numerical analysis shows that co-channel interference and signal fading significantly affect inter-vehicle connectivity.

A Prototype Orthogonal Vertical Beamforming for Indoor Wireless Communications

The concept of Orthogonal Vertical Beamforming (OVB) is proposed in this paper to eliminate interference when users remain at the same angle in the horizontal plane but are positioned at different distances. This orthogonal property helps systems avoid interference in the vertical direction of the mainbeam. A fully constructed prototype tested in a real indoor environment validates the proposed concept, revealing that the proposed OVB provides higher Signal Interference plus Noise Ratio (SINR) and Packet Error Rate (PER) in the vertical plane than conventional vertical beamforming and Orthogonal Beamforming.

Wavelength widths of optical filters for optimum SINR in WDM-VLC systems

Wavelength division multiplexing (WDM) permits the light spectrum to be divided into several parallel channels, allowing the capacity of visible light communication (VLC) systems to be increased. However, the spectral overlap due to the emission spread of differently colored LEDs generates crosstalk interference that can degrade the WDM-VLC. In this context, the adequate design of optical filters (OFs) can mitigate this problem by limiting the spectral capture of the signals from the adjacent WDM channels. Thus, a specific WDM-VLC model is developed to analyze the effects of the width of OFs on the signal-interference-plus-noise ratio (SINR). After confirming the quasi-concavity of the SINR, the optimal widths of the OFs are determined by SINR maximization using iterative search algorithms considering fixed and mobile WDM-VLC systems. Considering mobile receiver operation, it was confirmed that the maximum SINR points shift, implying the variation in optimal OF width according to the optical powers captured, which vary according to the distance and orientation of the LEDs and/or receivers. Finally, a statistical approach is presented that allows the design of non-adaptive OFs.

A novel mathematical teletraffic method to evaluate the interoperation of different standards with NOMA systems using order statistics

SummaryBasically, nonorthogonal multiple access (NOMA) allows controllable interferences by nonorthogonal resource allocation with a tolerable increase in receiver complexity, using successive interference cancellation (SIC). In this paper, authors show a novel mathematical model of teletraffic for users accessing, simultaneously, to Wi‐Fi and LTE services by using NOMA, calculating the birth–death process by order statistics. This methodology has not been previously used. The mathematical model is represented by a two‐dimensional Markovian process where the users can born or die in one system or another, independently, and results are validated through simulations. The outcomes demonstrate an increment of the sum‐rate gain for a system where users are ordered in the power domain using order statistics, according to the signal interference plus noise ratio (SINR), compared to a system where these statistics are not employed. By using the proposed mathematical model, the sum‐rate gain increases around 15%, and it is also demonstrated that this algorithm foresees a steady behavior of the sum rate, even when the number of channels is augmented, contrary when no order statistics are employed, in which the sum rate decreases considerably. On the other hand, the blocking probability is also demonstrated based on the chance of moving from one technology to another.

Resource Allocation in Satellite-Based Internet of Things Using Pattern Search Method

The emergence of Internet of Things (IoT) and high throughput satellite communication networks enables the capability of anytime, anywhere environment monitoring and sensing. A key challenge of satellite-based IoT is to enhance spectrum and energy efficiency so as to meet the ever-increasing demand for satellite bandwidth and dynamic access of a massive number of IoT terminals. In this paper, we propose a novel power control algorithm for IoT terminals being deployed in satellite-based IoT systems where some terrestrial base station is available to acquire IoT devices' information as well as to perform resource management. We adopted the Poisson point process (PPP) theory to formulate the model for this power optimization problem. The PPP theory is applied to evaluate the distance distribution of random IoT devices in this satellite-based networks. Optimal power control scheme can be obtained by taking into consideration user distribution and signal interference plus noise ratio (SINR) demand for various IoT terminals. In addition, due to the complexity of the objective function of power control deduced by the PPP theory, we utilize the pattern search method to identify an optimal solution in global area. Furthermore, we provide numerical results from various perspectives including user rates and energy efficiency to testify the performances of our power proposal.

Reduction of interference using Orthogonal Vertical Beamforming in an indoor communication

The interference between users is one of the factors that limit the achievable user throughput in the current indoor communication. In this paper, an evaluation of transmit beamforming contribution is analyzed in the context of an indoor environment. The technique of the Orthogonal Vertical Beamforming (OVB) has been proposed to reduce interference in an indoor communication. The proposed concept is validated through computer simulation in term of Signal Interference plus Noise Ratio (SINR). The obtained results show that the OVB provides higher performance over the conventional vertical beamforming and Orthogonal Beamforming (OBFM) in an only vertical plane.

Performance analysis of fractional frequency reuse in uplink random cellular networks

In this paper, we develop a network model based on 3GPP standards to analyse the performance of the uplink random cellular network using Frequency Reuse (FR) algorithms. The operation of FR is separated into two phases in which the Base Station (BS) measures the uplink Signal-Interference-plus-Noise Ratio (SINR) to classify each user into either Cell-Centre User (CCU) or Cell-Edge User (CEU) during the establishment phase. This is followed by the data transfer process between the user and its serving BS during the communication phase. Compared with the related works, we propose the following novel approaches: (i) we define the two-phase operation for both CCU and CEU; (ii) the density of interfering users causing interference to the CEU under Strict FR is inversely proportional to a FR factor; (iii) the interference originating from CCUs and CEUs are evaluated separately. Although Strict FR provides more benefits for the user such as low power consumption and higher performance than Soft FR, the network using Soft FR can achieve a significantly higher cell data rate which is up to 58.96% higher than that using Strict FR. A very interesting phenomenon is found in this paper for a sparse Strict FR network with the density of BSs λ=0.1BS∕km2 in which the average uplink SINR of the user during establishment phase increases with the power control exponent while the corresponding average data rate of the CCU during the communication phase reduces. The paper also derives the approximation analytical approach using Gaussian Quadratures to obtain the close-form expressions of user’s performance.

QoS aware admission and power control for cognitive radio cellular networks

AbstractIn cognitive radio cellular networks (CogCell), the secondary users (SUs) are allowed to access the channels licensed to the primary users (PUs) including Primary Transmitters (PTs) and Primary Receivers (PRs), only if the interference to the PRs is less than the predefined threshold, and the quality of service (QoS) requirements of PTs are guaranteed. In addition, different SUs may require different levels of QoS, and pay differently depending on the provided QoS. The network operator achieves different secondary revenues by admitting SUs in different QoS levels. The problem we address in this paper is to maximize the total secondary revenue relative to the interference constraints on PRs, and QoS requirements for both PTs and SUs. We formulate this optimization problem, and propose a power control scheme for both PTs and SUs. Then, we introduce three solutions including an exact solution using dynamic programming, a greedy heuristic algorithm, and a minimal signal‐interference‐plus‐noise‐ratio (SINR) removal algorithm. Based on these algorithms, we propose three QoS aware admission and power control (QAPC) schemes, one optimal solution called QAPC‐dynamic, and two approximate solutions called QAPC‐greedy and QAPC‐minimal SINR removal algorithm (MSRA), respectively. Numerical results show that QAPC‐dynamic always achieves the highest secondary revenue while QAPC‐MSRA gives the lowest secondary revenue. Since the time complexity of QAPC‐dynamic is much higher than the other two schemes, QAPC‐greedy is recommended considering the trade‐off between the computation complexity and performance gain. Copyright © 2009 John Wiley & Sons, Ltd.