• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.1
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• pp.65-71
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• 2022

In this paper, we propose an opportunistic data relay scheme in narrowband multihop combat radio networks. Narrowband networks have physical restrictions on high-speed transmission. Furthermore, the topology changes dynamically due to the jamming of the enemy, signal interference between friendly forces, and movement of network entities. Therefore, the traditional relay scheme that collects topology information and calculates a relay path before transmission is unsuitable for such networks. Our proposed scheme does not collect topology information and transmits data opportunistically. The scheme can cause unnecessary data relaying that is not related to data delivery to the destination node. However, for small networks, the effect of increasing network throughput by not gathering topology information is much greater than the effect of reducing throughput by unnecessary data relays. We demonstrate the performance superiority of the proposed scheme through simulation in the worst case of network topology.

• Journal of Communications and Networks
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• v.12 no.5
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• pp.433-441
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• 2010

Multihop transmission is a promising technique that helps in achieving broader coverage (excellent network connectivity) and preventing the impairment of wireless channels. This paper proposes a cluster-based multihop wireless network that makes use of the advantages of multihop relaying, i.e., path loss gain, and partial relay selection in each hop, i.e., spatial diversity. In this partial relay selection, the node with the maximum instantaneous channel gain will serve as the sender for the next hop. With the proposed protocol, the transmit power and spectral efficiency can be improved over those in the case of direct transmission and conventional multihop transmission. Moreover, at a high signal-to-noise ratio (SNR), the performance of the system with at least two nodes in each cluster is dependent only on the last hop and not on any of the intermediate hops. For a practically feasible decode-and-forward relay strategy, a compact expression for the probability density function of the end-to-end SNR at the destination is derived. This expression is then used to derive closed-form expressions for the outage probability, average symbol error rate, and average bit error rate for M-ary square quadrature amplitude modulation as well as to determine the spectral efficiency of the system. In addition, the probability of SNR gain over direct transmission is investigated for different environments. The mathematical analysis is verified by various simulation results for demonstrating the accuracy of the theoretical approach.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.43-51
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• 2015

Upcoming cellular networks such as LTE-advanced and IEEE 802.16m are enhanced by relay stations to support high data rate multimedia services and minimize the shadow zone with low cost. Enhancing the relay stations, however, divides the multihop cellular network into smaller microcells and the distance between microcells is closer, which intends large intra-cell and inter-cell interference. Especially the access link on downlink in the OFDMA cellular network is the throughput bottleneck due to the severe interference caused by base stations and relay stations transmitting large data to mobile stations simultaneously. In this paper, we present interference aware channel allocation algorithm to avoid severe interference on multihop cellular networks with random topology. Proposed algorithm increases SINR(signal to interference plus noise ratio) and decreases number of required control messages for channel allocation, so that increases overall throughput on the networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12A
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• pp.1198-1206
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• 2010

Recently smart phone and tablet PC are regarded as the most valuable mobile devices, so the demand of customers for multimedia supporting has been greatly increased. The network operators are now considering the deployment of relay stations ensuring low installation costs for its service cell to improve the cell capacity. Enhancing the relay stations, however, increases intra-cell interference, which is affecting the quality of service and outage ratio. In this paper, we present MPFR(Multihop Partial Frequency reuse) as the new frequency reuse scheme to increase cell throughput while maintaining low outage ratio for the OFDMA cellular multihop networks. Dynamic power control is also introduced to improve cell capacity. Overall cell throughput and outage ratio are observed by the simulation, and comparison between MPFR and conventional multihop frequency reuse schemes is convincing the performance enhancement.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.401-405
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• 2007

In sensor network, cluster based routing protocol about efficient energy usage method has researched variously. But existing cluster based routing protocol have problems. one of the problem is sensor nodes's imbalance energy consumption problem at cluster reconstruction. anther is non- connection problem between header node and spc node when they are far from each other, not properly connected. We propose cluster re-division and header node of multihop transmission method in this paper. The cluster re-division method is the method that re-divides existing routing protocol with the small-scale cluster and multihop transmission method is the method regarding the relay transmission between the header nodes. Through the simulation, the proposed routing mechanism shows more excellent than exiting routing protocol in balance energy consumption and energy efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.12
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• pp.1138-1147
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• 2012

IEEE standard 802.16, often referred to as WiMAX, is considered a "last mile" broadband wireless access alternative to conventional DSL and Cable Internet. One extension that is recently receiving great attention is the IEEE 802.16j Mobile Multihop Relay (MMR) amendment. The focus of this amendment is the development of simple and lower cost relay stations (RSs) that can enhance network coverage and capacity. We use our proposed simple scheduling scheme for serving the SSs in a fair manner and evaluate the performance of WiMAX networks with relays, especially we analyze the impact of interference between RSs on cell throughput Through simulations and numerical analysis, we make several fundamental observations about interference aware cost effective coverage extension in such networks.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.11
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• pp.5264-5281
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• 2017

Multihop relay-based cellular networks are attracting much interest because of their throughput enhancement, coverage extension, and low infrastructure cost. In these networks, relay stations (RSs) between a base station (BS) and mobile stations (MSs) drastically increase the overall spectral efficiency, with improved channel quality for MSs located at the cell edge or in shadow areas, and enhanced throughput of MSs in hot spots. These relay-based networks require an advanced radio resource management scheme because the optimal amount of radio resource for a BS-to-RS link should be allocated according to the MS channel quality and distribution, considering the interference among RSs and neighbor BSs. In this paper, we propose optimal resource planning algorithms that maximize the overall utility of relay-based networks under a proportional fair scheduling policy. In the first phase, we determine an optimal scheduling policy for distributing BS-to-RS link resources to RSs. In the second phase, we determine the optimal amount of the BS-to-RS link resources using the results of the first phase. The proposed algorithms efficiently calculate the optimal amount of resource without exhaustive searches, and their accuracy is verified by comparison with simulation results, in which the algorithms show a perfect match with simulations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.911-916
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• 2016

The nearest-neighbor multihop routing with/without infrastructure support is known to achieve the optimal capacity scaling in a large packet-erasure network in which multiple wireless nodes and relay stations are regularly placed and packets are erased with a certain probability. In this paper, a throughput scaling law is shown for an infrastructure-supported erasure network where wireless nodes are randomly distributed, which is a more feasible scenario. We use an exponential decay model to suitably model an erasure probability. To achieve high throughput in hybrid random erasure networks, the multihop routing via highway using the percolation theory is proposed and the corresponding throughput scaling is derived. As a main result, the proposed percolation highway based routing scheme achieves the same throughput scaling as the nearest-neighbor multihop case in hybrid regular erasure networks. That is, it is shown that no performance loss occurs even when nodes are randomly distributed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2A
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• pp.133-138
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• 2011

This paper presents an information theoretic outage analysis for physical layer of a cooperative multihop wireless network. Our analysis shows that cooperation by selecting a proper relay at each hop increases the coverage or data rate of the network. In our analysis we consider both symmetric and asymmetric network model. We also investigate the availability of cooperative relay at each hop and show that end-to-end performance of the network depends on the relay selection procedure at each hop. We also verify our analytical results with simulations.

• ETRI Journal
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• v.35 no.2
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• pp.234-244
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• 2013

Internet protocol television (IPTV) service depends on the network quality of service (QoS) and bandwidth of the broadband service provider. IEEE 802.16j mobile multihop relay Worldwide Interoperability for Microwave Access networks have the opportunity to offer high bandwidth capacity by introducing relay stations. However, to actually satisfy QoS requirements for offering IPTV services (HDTV, SDTV, Web TV, and mobile TV) for heterogeneous users' requests, providers must use a video server for each IPTV service type, which increases the network load, especially bandwidth consumption and forwarding time. In this paper, we present a solution for forwarding IPTV video streaming to diverse subscribers via an 802.16j broadband wireless access network. In particular, we propose a new multicast tree construction and aggregation mechanism based on the unique property of prime numbers. Performance evaluation results show that the proposed scheme reduces both bandwidth consumption and forwarding time.