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This paper considers multiuser cooperative relay networks with user selection at the mobile station, where both the relay and mobile users are corrupted by a finite number of co-channel interferers. We study the impact of the outdated channel state information (CSI) on the system performances over time-varying Rayleigh fading channels by deriving the tight lower bounds for the outage probability and...
In a vehicular delay tolerant network, the problem of scheduling the traffic from a roadside unit to passing-by vehicles is studied. A cost function is associated with a scheduled transmission. And if a delay bound is violated, a penalty cost is charged. The optimal stopping theory is applied to decide when the roadside unit should schedule its accumulated traffic to a passing-by vehicle such that...
This paper considers a multiuser two-way relay network (TWRN) consisting of one base station (BS), one amplify-and-forward (AF) relay and K mobile stations (MSs) among which the Nth-best MS is selected to exchange information with the BS. Specifically, we study the impact of outdated channel state information (CSI) on the system over time-varying Rayleigh block-fading channels by deriving a tight...
Delay tolerant networks are intermittently connected. In this paper, we propose a DTN routing scheme EBR. The scheme is based on the idea of exploiting inter-contact time between mobile nodes to predict the number of nodes with no copy a node will encounter within the expected delay. In EBR, every node with message copies dynamically chooses the number of copies by itself. We evaluate the performance...
A reliable and secure communication network plays a significant role in Smart grid systems, which aims at coordinating generation, transmission, distribution, and consumption parts in power system. The scope of our work ranges from utility level to end consumption level. The major difficulties in this work can be summarized as follows: 1) Performance requirements from the viewpoint of network have...
This design mainly aims at the small and medium-sized enterprise. On its existing internal integration local area network, it realizes the special-purpose IP telephone network in the enterprise, and it also realizes the main purpose that is the “zero” long-distance phone bill trans-regional enterprise. Because of VoIP is the technology of analog voice signal digitized and making the real-time transmission...
Network coding has been shown to be able to improve the throughput and power efficiency of wireless networks by mixing packets from different flows into a single packet. However, forcing packets to be coded may induce large delay and packet loss rate which is intolerable to some services such as real-time communications. Considering the diversity of traffic flows and the stochastic nature of the packet...
Cooperative wireless networks supporting multiple services necessitate the application of a robust bandwidth allocation policy to ensure Quality of Service (QoS) provision to different applications. In this work, a load dependent bandwidth allocation technique is presented considering traffic priority and buffer load in the relay nodes of a cooperative communication network. An analytical approach...
In this paper we study the delay characteristics of cooperative communications using opportunistic relay access with delay constraints. We consider the scenario where the source node opportunistically tries to access the relay, amongst several Primary Users (PU) of the relay network in the environment, in order to send data across (a fixed) network to its destination. The first-hop connection for...
This paper proposes a distributed pricing-based user cooperation strategy for a two-user model focusing on performance from the delay perspective. It explores the fact that cooperation (i.e., one-way relaying as opposed to mutual relaying) is beneficial when users channel conditions are distinct. The strategy only allows valuable cooperation, i.e., the user with a good channel helps relay the packet...
Through sensing and utilizing available network resources, cognitive network can obviously increase network performance. In this paper, a distributed on-demand routing protocol with traffic awareness (TACR) is proposed for cognitive wireless network. This routing protocol establishes the path based on the cognition and reasoning of traffic loads in a network and it also meet quality of service (QoS)...
Delay Tolerant Networks (DTNs) are characterized by intermittent connectivity, high delay and without end-to-end path from the source to the destination. The fundamental way of message routing in DTNs is store-and-forward. Thus, the mal-behaving nodes in the networks, which are uncooperative to relay messages, will significantly undermine the routing performance. In this paper, we propose a novel...
IEEE 802.16j is to enable the operation of multi-hop Relay Stations (RS). It aims to enhance the coverage, per user throughput and system capacity of IEEE 802.16e. However, the Mobile Stations (MSs) which connect to the RS are suffering from exponentially throughput degradation and end-to-end delay increase in congested network. As the number of RS hops increases, so does the degradation and the delay...
Delay/Disruption Tolerant Networks (DNTs) enables nodes to communicate by means of asynchronous sending messages without the need for an end-to-end path. In this paper, we study the problem of multicasting in DTNs. Several schemes have been proposed for multicast routing assuming the group of message receivers is known by sender, and the group members do not change during the process of message delivery...
In this paper we present a novel technology named probability dynamic relay handover (PDRH) for the benefit of providing a mechanism to recover from selective attacks on some important terminals of JTIDS. The key points of PDRH are the probability model to simulate selective attacks using the theory of scale-free network and addressing for a new relay node. In simulation based on OPNET Modeler 10...
We consider a relay-assisted wireless communication system where relays are given the capability of scheduling function. We evaluate and compare the performances of voice over internet protocol (VoIP) in orthogonal frequency division multiple access (OFDMA) systems where two different scheduling capabilities of relays are employed in each system. In the system with relays that have the scheduling...
In this paper we present a novel technology named dynamic relay handover (DRH) for leveraging DSR and AODV for the benefit of providing a guaranteed network performance. The key points of DRH are the connectivity checking of the existing relay node and the assignment of a new relay node. In simulation of this algorithm based on OPNET Modeler 10.5, the effect of DRH on the network performance and the...
IEEE 802.15.4 was developed to meet the needs for simple, low-power and low-cost wireless communication. In the past couple of years it has become a popular technology for wireless sensor network. But in practical projects, we find that a long association delay is a critical problem in some real-time applications. This paper proposes a new association scheme named fast association mechanism (FAM)...
In this paper we propose a new algorithm for selective relay strategies with Amplify-and-Forward (AF) relays which improves the relay network lifetime. The lifetime of the relay network is defined as the maximum number of messages which can be received with the desired SNR at the destination while the system Probability of Outage (P-outage) requirement is satisfied. The improvement in lifetime increases...
In classical routing strategies for multihop mobile wireless networks packets are routed on a pre-defined route usually obtained by a shortest path routing protocol. In opportunistic routing schemes, for each packet and each hop, the next relay is found by dynamically selecting the node that captures the packet transmission and which is the nearest to the destination. Such a scheme allows each packet...
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