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New results on the achievable trade-off between the per-node throughput T(n) and the average delay D(n) in a static wireless network of n nodes are presented for physical link models. For links modeled by channels with additive white Gaussian noise with power-law attenuation, a trade-off of only D(n) = ⊖ (n (log n) T(n)) is guaranteed for T(n) = ⊖(n−½). This follows from showing that there is significant...
A Wireless Networked Control Systems review is presented. It begins with a brief history about NCS (Networked Control Systems), recognizing the fundamental features, its advantages over other classical control systems, and the protocols that can be used to do control over the wireless network. Also, we deal with the different problems that can affect the network behavior; including interferences and...
In this work, the distributed power allocation problem in universal mobile telecommunication systems (UMTS) is studied under feedback signal-to-noise ratio (SNR) constraints. The sources of uncertainty are assumed to come from the quantization process and measurement noise in the closed-loop system. The power allocation problem is formulated as a reference tracking problem of a pre-defined signal...
In this paper, the performance of parallel interference cancellation (PIC) multiuser detector in orthogonal frequency division multiple access (OFDMA) mobile communication systems is investigated. In multiuser systems, the multi-user interference (MUI) degraded the system performance, especially in near-far effect environments. The PIC scheme is proposed to reduce the MUIs and to improve the bit error...
Channel assignment has been extensively researched for multi-radio wireless mesh networks, but it is still very challenging when it comes to its implementation. In this paper we propose a semi-dynamic and distributed channel assignment mechanism called SICA that uses game theory. To the best of our knowledge this is the first game formulation of channel assignment which takes the co-channel interference...
We analyze the problem of buffer sizing for TCP flows in 802.11-based Wireless Mesh Networks. Our objective is to maintain high network utilization while providing low queueing delays. The problem is complicated by the time-varying capacity of the wireless channel as well as the random access mechanism of 802.11 MAC protocol. While arbitrarily large buffers can maintain high network utilization, this...
In this paper, the impact of both time offsets (TOs) and carrier frequency offsets (CFOs) on the average output signal-to-interference-plus-noise ratio (SINR) in a frequency selective channel is investigated with a novel approach. First, TOs are partitioned into five cases based on how they occur. Then the mathematical models for different cases are derived. Considering CFOs and benefiting from the...
This work studies the power control algorithm proposed by Foschini-Miljanic (1993), standardized for universal mobile telecommunication systems (UMTS). Continuous and discrete time versions of this algorithm are analyzed. First, it is shown that the distributed power allocation scheme can be visualized as a tracking problem of an equivalent power reference that specifies the desired quality-of-service...
In Wireless Sensor Network MAC protocol designs, end to end latency is a field that many researches often focus on. RMAC, as a synchronizing MAC protocol, shows great advantage in reducing end to end latency than other MAC protocols. However, the performance of RMAC degenerates when encountered with interference hotspots. In this paper, we present an enhanced MAC protocol called SRMAC, which is derived...
This paper proposes AODV Routing cross-layer based on multiple criteria optimization mechanism to solve the network congestion caused by node load imbalance. This mechanism is proposed by integrating the minimum hop of the network layer and the interference and data rates of physical layer. Then through theoretical analysis and NS2 simulation, the experiment results prove this mechanism has a lower...
One of the major problems in GSM-based passive detection systems is how to suppress the strong direct path interference (DPI) effectively. According to the features of the GSM downlink signal and the DPI suppression requirement, a spatial filtering algorithm based on the direction of arrival (DOA) information and a least square null constraint optimization is proposed. Theoretical analyses and simulation...
Locomotive synchronization operation and control(LSOC) system is a train control system based on LOCOTROL technique and GSM for railway (GSM-R) system for heavy haul railway. The current QoS requirements of GSM-R are designed for train control message transmission (TCMT) service of ETCS, which are not suitable for LSOC service with different characteristic. Therefore, the reasonable QoS requirement...
SC-FDMA is a multiple access technique adopted in LTE uplink transmission. SC-FDMA, as well as OFDMA, can improve system throughput by assigning different frequency portions of system bandwidth to different user equipments (UEs) adaptively based on their channel quality information. In SC-FDMA uplink cellular system, interference arising from UEs in neighboring cells degrades system performance, especially...
Cooperative ARQ schemes are effective to enhance the quality of communication for the next generation mobile communication systems. In this paper, we propose a cooperative ARQ strategy for supporting instantaneous cooperation in MANET environment using ad hoc cognitive relays. In the proposed strategy, whenever a data frame is transmitted from the source, nearby relays actively sense the SINR of the...
The employment of wireless mesh networking in real- life scenarios has attracted substantial research interest in recent years and in this context VoIP has become a ubiquitous application. However, it has been demonstrated that VoIP transmissions over a multihop network may still remain inadequate in terms of their high packet-loss ratio and network- induced delays. To alleviate these limitations,...
We address the analytical design of a communications system that seeks to provide timely safety information for drivers who are unaware of an imminent collision. We develop a model to characterize the delay requirements needed to prevent such collisions. By simultaneously addressing the multi-user interference and propagation effects such as path loss and fading, we then analytically derive the optimal...
The use of MIMO (Multiple Input Multiple Output) in current and future mobile communications relies on accurate channel estimates. In OFDM based systems such as LTE (Long Term Evolution), the channel estimation can be successfully designed with processing in a transform domain, both for uplink and downlink. One such popular transform is to use the IDFT (Inverse Discrete Fourier Transform), window...
Interference mitigation by applying Joint Processing (JP) in cooperative cellular networks boasts cell-edge performance compared to non-cooperative systems. However, downlink JP requires knowledge of Channel State Information (CSI) at all collaborating Base Stations (BSs), where interference received at the User Equipments (UEs) is markedly affected by the level of CSI quality influenced amongst others...
Wireless Body Area Networks (WBANs) offer tremendous benefits for remote health monitoring and real-time patient care. However, the success of such a system would primarily depend on the reliability of the data transmitted by the WBAN. Two aspects of data reliability need to be considered, namely, data accuracy and data freshness (or, recentness of data). Assuming that the sophistication of the sensors...
This paper presents the new result in the Trajectory approach when considering more than one packet of a sporadic flow is overstocked on an output port for an AFDX network, using the FIFO assumption. The principal contribution is to compute upper bounds of end-to-end delays for the processing flows by the recursive calculation of interference time windows. The paper proposes a memo recursive computation...
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