Current Issue : October - December Volume : 2016 Issue Number : 4 Articles : 5 Articles
Modern society demands cheap, more efficient, and safer public transport. These enhancements, especially an increase in efficiency\nand safety, are accompanied by huge amounts of data traffic that need to be handled by wireless communication systems. Hence,\nwireless communications inside and outside trains are key technologies to achieve these efficiency and safety goals for railway\noperators in a cost-efficient manner.This paper briefly describes nowadays used wireless technologies in the railway domain and\npoints out possible directions for future wireless systems. Channel measurements andmodels for wireless propagation are surveyed\nand their suitability in railway environments is investigated. Identified gaps are pointed out and solutions to fill those gaps for\nwireless communication links in railway environments are proposed....
Machine-to-machine (M2M) communication is becoming an increasingly essential part of mobile traffic and thus also\na major focus of the latest 4G and upcoming 5G mobile networks. M2M communication offers various ubiquitous\nservices and is one of the main enablers of the Internet-of-things (IoTs) vision. Nevertheless, the concept of mobile\nM2M communication has emerged due to the wide range, coverage provisioning, high reliability as well as\ndecreasing costs of future mobile networks. Resultantly, M2M traffic poses drastic challenges to mobile networks,\nparticularly due to the expected large number of devices sending small-sized data. Moreover, mobile M2M traffic is\nanticipated to degrade the performance of traditional cellular traffic due to inefficient utilization of the scarce radio\nspectrum. This paper presents a novel data aggregation and multiplexing scheme for mobile M2M traffic and thus\nfocuses on the latest 3GPP (3rd Generation Partnership Project) tong-term-evolution-advanced (LTE-A) networks. 3GPP\nstandardized layer 3 inband Relay Nodes (RNs) are used to aggregate uplink M2M traffic by sharing the Physical\nResource Blocks (PRBs) among several devices. The proposed scheme is validated through extensive system level\nsimulations in an LTE-A based implementation for the Riverbed Modeler simulator. Our simulation results show that\nbesides coverage extensions, RNs serve approximately 40% more M2M devices with the proposed data multiplexing\nscheme compared to the conventional without multiplexing approach. Moreover, in this paper an analytical model is\ndeveloped to compute the multiplexing transition probabilities. In the end, the simulation and analytical results of\nmultiplexing transition probabilities are compared in order to analyze the multiplexing scheme....
Ethernet network, standardized by IEEE 802.3, is vastly installed in Local Area Network (LAN) for\ncheaper cost and reliability. With the emergence of cost effective and enhanced user experience\nneeds, the Quality of Service (QoS) of the underlying Ethernet network has become a major issue.\nA network must provide predictable, reliable and guaranteed services. The required QoS on the\nnetwork is achieved through managing the end-to-end delay, throughput, jitter, transmission rate\nand many other network performance parameters. The paper investigates QoS parameters based\non packet size to analyze the network performance. Segmentation in packet size larger than 1500\nbytes, Maximum Transmission Unit (MTU) of Ethernet, is used to divide the large data into small\npackets. A simulation process under Riverbed modeler 17.5 initiates several scenarios of the\nEthernet network to depict the QoS metrics in the Ethernet topology. For analyzing the result from\nthe simulation process, varying sized packets are considered. Hence, the network performance\nresults in distinct throughput, end-to-end delay, packet loss ratio, bit error rate etc. for varying\npacket sizes....
Due to the rapid growth of mobile data traffic, more and more basestations and access points (APs) have been densely deployed\nto provide users with ubiquitous network access, which make current wireless network a complex heterogeneous network\n(HetNet). However, traditional wireless networks are designed with network-centric approaches where different networks have\ndifferent quality of service (QoS) strategies and cannot easily cooperate with each other to serve network users. Massive network\ninfrastructures could not assure users perceived network and service quality, which is an indisputable fact. To address this issue,\nwe design a new framework for heterogeneous wireless networks with the principle of user-centricity, refactoring the network\nfrom users� perspective to suffice their requirements and preferences. Different from network-centric approaches, the proposed\nframework takes advantage of Software DefinedNetworking (SDN) and virtualization technology, whichwill bring better perceived\nservices quality for wireless network users. In the proposed user-centric framework, control plane and data plane are decoupled\nto manage the HetNets in a flexible and coadjutant way, and resource virtualization technology is introduced to abstract physical\nresources of HetNets into unified virtualized resources. Hence, ubiquitous and undifferentiated network connectivity and QoE\n(quality of experience) driven fine-grained resource management could be achieved for wireless network users....
A huge increase of machines attached to wireless networks is expected in the next few years. A large part of these\nmachines will be covered by some wireless wide area networks. The arrival of cellular M2M (machine-to-machine)\ncommunication poses new requirements due to its specific characteristics. For most of the cellular M2M applications,\nthe essential requirement is low energy consumption level or high energy efficiency. This survey provides a global\nview of the network technologies previewed for cellular M2M. In this survey, we study the existing classifications of\nM2M applications according to different criteria in the literature. The comparison of traffic characteristics between\nM2M and human-to-human is also proposed. Quality of service (QoS) requirements for typical M2M applications are\nresumed. The advance of reference M2M network architectures proposed by the Standard Development Organization\n(SDO) is investigated. We identify two possible effort directions to improve the energy efficiency for cellular M2M. The\nfirst one is to evolve the current existing 3rd Generation Partnership Project (3GPP) Consortium cellular networks to\neffectively support MTC (Machine Type Communication). The other direction is to design M2M-dedicated networks\nfrom scratch, which are often called low-power wide-area (LPWA) networks. We review, compare and categorize the\nproposals related to energy issues of cellular M2M mainly over the period 2011ââ?¬â??2015 for the first direction. We\nintroduce the development of LPWA networks for the other research directions. We highlight that the cooperative\nrelaying, the design of energy-efficient signaling and operation, the new radio resource allocation schemes, and the\nenergy-efficient random access procedure are the main points of improvement. It is important to jointly use the\naforementioned approaches, for example, joint design of random access control and radio resource allocation, to seek\nfor a trade-off between energy efficiency and other system performances....
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