In this paper, we describe the effect of interference cancellation in the receiver for D2D communication. The relationship between nodes for interference cancellation in the receiver is derived and then the effect of interference cancellation is analyzed from perspectives of the number of nodes, the power consumption, and the sum spectral efficiency. In addition, the range of power control for interference cancellation is described. The analysis shows that interference cancellation in the receiver results in the performance gain from the point of view of the sum spectral efficiency in spite of the power consumption.

Recent standardization efforts in the 3rd Generation Partnership Project (3GPP) have made the Long Term Evolution (LTE) system a very attractive radio access technology for various types of devices and applications. However, the system has not yet been optimized to support diverse traffic profiles. In this paper, we propose a group-based communication scheme to alleviate inefficiencies in the radio access network. The proposed scheme groups multiple connections triggered by different User Equipments (UEs). For the efficient grouping of the UEs, the location information of the Machine-Type Communication (MTC) devices is utilized to identify each group. A four-phase system model is presented to analyze each segment of the connection establishment procedure in the access network. We found that the random access procedure is the main variable factor for the communication delay, and we, therefore, carefully design the procedure with details. Simulations are conducted on our LTE testbeds, and the results show that the proposed scheme is very effective in ensuring the system performance of legacy services and in utilizing radio resources within a given delay bound.

Network coding is increasingly being investigated as an alternative to routing to increase throughput in packet networks. Like most data transfer schemes, the effectiveness of network coding may be limited by extreme congestion. When using network coding, these congested conditions are mitigated somewhat, but may still occur. We propose a selective channelization scheme in which links that experience congestion at a level that cannot be overcome by network coding are given reserved communication resources. This method has the following benefits. First, the algorithm proposed allows network coding full opportunity to overcome congestion before performing channelization, thus reducing the number of reserved resources used. Second, when triggered, the channelization of severely congested links greatly improves the end-to-end performance of flows that traverse the channelized link. To determine the point at which channelization should be triggered, we perform a thorough analysis of potential coding gains in a network facing errors due to collisions, and determine the point at which network coding loses its effectiveness.

In typical deployments of infrastructure wireless mesh networks, mesh clients are directly connected to a mesh router. The mesh routers form a multi-hop wireless mesh backbone to provide connectivity to the Internet. In this paper, we propose and evaluate a set of distributed algorithms that enable mesh clients to form a multi-hop wireless relay network to have access to the mesh backbone. The proposed algorithms include path discovery, channel allocation, path selection, and local tuning of the resulting relay network. Results show that the performance of the relay network formed by our algorithms is very close to the optimal performance that the network can achieve.

Wireless mesh networks are emerging as a means to provide ubiquitous network connectivity using various radio technologies. In this paper we propose and evaluate a set of distributed algorithms to form a multi-hop relay network to access the backbone in wireless mesh networks. The proposed algorithms include path discovery, frequency allocation, path selection, and local tuning of the resulting relay network. Our results show that the performance of the relay network formed by our algorithms is very close to the optimal performance that the network can achieve.

Mobility management protocols allow wireless devices to move between networks. These protocols have traditionally supported the mobility of individual nodes and are therefore not optimized to support the migration of groups. Accordingly, the time required to re-establish connectivity, frequency of dropped packets and contention for the air interface increase significantly for mobile groups. We propose a protocol for mobile groups that reduces all of the above by allowing a single node to perform handoffs on behalf of all group members. This "gateway" node eliminates the need for multiple handoff messages by obscuring group membership to external parties. Through extensive simulation and implementation, we show significant reduction in handoff times, message complexity and packet loss for groups of heterogeneous, mobile sensors running AODV and DSDV. By leveraging the naturally occurring hierarchy, we demonstrate that it is possible for groups to efficiently use traditional mobility protocols to support their collective movements.

Nodes forward data on behalf of each other in mobile ad hoc networks. In a civilian application, nodes are assumed to be selfish and rational, i.e., they pursue their own self-interest. Hence, the ability to accurately measure traffic forwarding is critical to ensure proper network operation. These measurements are often used to credit nodes based on their level of participation, or to detect loss. Past solutions employ neighbor monitoring and reporting on node forwarding traffic. These methods are not applicable in civilian networks where neighbor nodes lack the desire or ability to perform the monitoring function. Such environments occur frequently in which neighbor hosts are resource constrained, or in networks where directional antennas are used and reliable monitoring is difficult or impossible. In this paper, we propose a protocol that uses nodes on the data path to securely produce packet forwarding reports. Reporting nodes are chosen randomly and secretly so that malicious nodes cannot modify their behavior based upon the monitoring point. The integrity and authenticity of reports are preserved through the use of secure link layer acknowledgments and monitoring reports. The robustness of the reporting mechanism is strengthened by forwarding the report to multiple destinations (source and destination). We explore the security, cost, and accuracy of our protocol.

Session-based Internet protocol (IP) applications, such as Internet telephony, are an important component of the emerging mobile Internet. The ubiquitous availability of these services is critical to the success of the mobile Internet. Because all-IP networks will be deployed in phases and current mobile telecommunication systems will be in operation for decades to come, the interworking and migration between current network services and all-IP services is a key problem. In this paper, we address seamless roaming for session initiation protocol-based services across current cellular telecommunication networks and emerging all-IP wireless networks, such as those using third-generation and WiFi networks. We present an abstract mobility model, and map this model to three basic approaches for supporting seamless mobility: a master-slave approach, a federated system, and a unified approach. We discuss the challenges and implementation of an instance of the unified mobility management approach, called the Unified Mobility Manager, and then compare the tradeoffs of the three systems using a comparative performance analysis. We conclude that unified mobility management is most efficient if a great deal of interworking is required, and as more users invoke IP-based services; the federated approach is efficient when a single network technology is dominant and data access is limited, but requires sharing of data across networks; the master-slave approach is the least efficient, but is easy to introduce if the number of network types is small.