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This paper addresses the fairness of Medium Access Control (MAC) protocols that are capable of handling interference on the physical layer to a varying extent. The variation addressed is thereby not based on different physical layer techniques applied, but on differing attribute levels of the same physical layer technique. This can e.g., be a varying number of antennas at each node in case of Multiple...
For distributed antennas based communications, the received signal from different sources can be asynchronous due to the propagation or processing delays. This can destroy the space time block code properties designed initially for synchronous case. In this paper, we introduce the delay-diversity tradeoff showing that it is possible to preserve the maximum diversity of a code without reducing its...
This paper introduces a technology convergence adaptor for a previously presented Inter-MAC architecture for heterogeneous home area networks. Its main task is to translate technology-dependent link metrics into a machine readable common language. This language allows for the description of various service and application classes and provides means to describe link metrics of underlying MAC protocols...
TCP's downlink performance during FMIPv6-enabled IEEE802.11g handoff is examined. The use of a user-initiated Handoff Notification, sent prior to handoff, is proposed. Therefore, the correspondent node is aware of the handoff-induced disruption, hence avoiding dropping the congestion window size and triggering Fast Retransmission mechanisms. During handoff, it continues to send data packets which...
Cognitive radio (CR) technology has been considered promising to enhance spectrum efficiency via opportunistic transmission at link level. To make CR useful, networking CRs to form a cognitive radio network (CRN) is able to support end-to-end transmission from CR source to CR destination. However, the opportunistic nature of CR link for interference avoidance to primary users degrades the quality-of-service...
The success and efficiency of managing an emergency situation (such as rescue operation, fire fighting etc.) depends on enabling a system that would ensure the timely availability of high-quality and latest information to the emergency Mobile Units (MU). The system must ensure the provisioning of relevant information in a secure manner irrespective of the location and/or mobility of the MU. The enabling...
Along with LTE-Advanced system and standardization investigation progress, the requirement for verifying relevant key technologies become more and more urgent. This article summarizes the progress of Huawei 4G Test-bed “HEART” (Huawei Experimental Advanced Radio Test-bed). CoMP technology is considered as a launch point to build up this test-bed competence. Some initial analysis and results are addressed...
In this paper, we evaluate the delay experienced by Poisson arriving packets for Cooperative truncated HARQ with opportunistic relaying in the presence of a noisy feedback channel. We derive the theoretical expressions of the expected waiting time and the packet's sojourn time in the queue of truncated opportunistic cooperativeARQ and Hybrid ARQ I, with and without Packet Combining (PC), and Hybrid...
Numerous investigations of mobile radio communication have been conducted in environments such as urban, outdoor-to-indoor or indoor, only a few are in ruins. Within a running project, I-LOV, a study of a mobile radio propagation channel in urban search and rescue scenarios is conducted. Due to complex environment in ruins, great multipath interference can take place, which strongly impacts communication...
This paper concentrates on characterizing energy, latency and capacity trade-offs in multi-hop wireless ad-hoc networks. Therefore, a multiobjective framework is proposed to derive the Pareto-optimal set of solutions with respect to these three criteria. The work presented in this paper assumes a linear network where transmission powers and relay positions are optimization variables. We study the...
P2P (peer-to-peer) streaming systems are getting more and more popular in recent years. P2P streaming architectures can be classified into tree-based and mesh-based. The tree-based architecture has low start-up delay, but is less resilient to node failures compared to the mesh-based architecture, and it would result in a low delivery ratio and unstable quality of received multimedia. In this paper,...
In this paper we analyze the Ricean K-factor for vehicle-to-vehicle (V2V) communications in a typical open sub-urban street crossing. The channel conditions vary from non line-of sight (NLOS) to line-of-sight (LOS). The antenna arrays used for recording the radio channels consist of 4 elements with directional radiation patterns. We measured 16 individual single-input single-output channels, with...
This paper proposes the utilization of GSM logical channels (RACH, AGCH and TCH) and UMTS signaling (MIB and SIBs) of the Broadcast Channel to transmit a Cognitive Beacon Channel (CBC). The CBC will help to improve spectrum awareness by conveying signalization to mobile users in a multi-Radio Access Technology (RAT) environment (e.g. 3GPP, Wi-Fi, WiMAX and future cognitive radio systems). Taking advantage...
Previous work predominantly assumes that the pdf of range measurements exhibit Gaussian characteristics. The objective of this paper is to scrutinize this assumption for different environments. Experiments are performed in both outdoor and indoor environments with Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) conditions using IEEE 802.15.4 compliant devices. These devices consist of a low-cost...
In this paper, the results of outdoor-to-indoor multiple-input multiple-output (MIMO) channel measurements at 780 MHz are presented. The motivation for these measurements was to provide actual measurement data needed to extend the International Mobile Telecommunications -Advanced (IMT-A) channel models to the frequencies around 400 - 900 MHz. There are publications reporting measurement results for...
The IEEE 802.11 standard conformant wireless communication stations have multi-rate transmission capability. To achieve greater communication efficiency, multi-rate capable stations use rate-adaptation to select appropriate transmission rate according to variations in the channel quality. This paper proposes a novel rate-adaptation scheme where the decision of rate selection relies on the mutual feedback...
Machine-to-Machine (M2M), an emerging communications paradigm, is a facilitator of data flows between machines used, e.g., in mission-critical applications. Focusing in this paper on embedded multihop M2M implementations with myopic routing, a prime design aim is to jointly minimize energy expenditure and the end-to-end delay whilst not jeopardizing the network's operational reliability. We thus evaluate...
This paper proposes an analytic model to study queuing effect on the handoff performance of Mobile IPv6 (MIPv6), which has not been particularly investigated in previous literature. The presented model regards handoff process as tandem service system, and adopts a simple two-moment approximation throughout the theoretic modeling. Without other specific assumptions, the model presents a generic approach...
In cognitive radio networks, spectrum sensing is a fundamental function for detecting the presence of primary users in licensed frequency bands. Due to multipath fading and shadowing, the performance of detection may be considerably compromised. To improve the detection probability, cooperative sensing is an effective approach for secondary users to cooperate and combat channel impairments. This approach,...
Wireless multihop ad hoc networks face a multitude of challenging problems including highly dynamic multihop topologies, lossy and noisy communication channels, and sporadic connectivity which contribute to frequent link failures. Rapid and accurate link failure detection is therefore important to maintain correct and optimum operation of network routing protocols. In this paper, we propose a unified...
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