Cluster-Based Design for Two-hop Cellular Networks

Optimal resource allocation with an objective of maximizing the system capacity is an NP-hard problem in multihop cellular networks. Hence, different heuristic algorithms have been developed over the years that would improve the network system capacity. In this paper, a novel cluster-based architecture is proposed for a two-hop cellular network whereby the transmission distance between any communicating pair is restricted to half the cell radius. In this design, a given radio resource is used by two simultaneously communicating pairs in every hexagonal cell, but for only half the time slot period. The characteristic feature of this cluster-based design is that it enables a frequency reuse ratio of one. The proposed hierarchical system is analyzed and tested under realistic propagation conditions including lognormal shadowing. It has been observed that the system capacity of a cluster-based design is 2.5 times that obtained from the single-hop cellular system with no relaying. In addition, the cluster-based design achieves higher capacity compared to state-of-the-art two-hop algorithms. This is an important finding since the hierarchical cluster-based approach has fewer degrees of freedom in the selection of the routing path for the end-to-end connection. Practical routing algorithms should be able to benefit from this.

Optimal Positions of Relay Stations for Cluster-Based Two-Hop Cellular Network

Multihop cellular networks is an exciting and a fledgling area of wireless communication which offers huge potential in terms of coverage enhancement, data-rates, power reduction, and various other quality of service improvements. However, resource allocation in MCN is an NP-hard problem. Hence, significant research needs to be done in this field in order to efficiently design the radio network. In this paper, optimal position of relay stations in a hierarchical cluster-based two-hop cellular network is investigated. Vector algebra has been used to derive general equation for carrier-to-interference ratio (C/I) of a mobile station. It has been observed that when the transmit power of base station (BS) and the gateway (GTW)/relay station (RS) are same, the RSs should be located close to mid-point of BS and the edge of the cell. However, significantly, when the transmit power of the BS is greater than that of the GTW, then the RSs should be placed closer to the edge of the cell, in order to maximize the minimum C/I at any point in the cell. This in turn results in higher modulation technique at the physical layer, and hence, a higher data-rate to all the users in the system.

3D E-CRUSE:Energy-based throughput analysis of three dimensional underwater network using RF communication

Monitoring the ocean shore continuously in real-time is essential for important applications like port security,coastal surveillance,assistance in navigation etc.This needs a high data rate for the transmis-sion of data from underwater nodes to the surface.Acoustic communication is the traditional approach for underwater networks and offers long-range communication.However,the achievable data rate using acoustic communication is in the order of kbps only.Radio frequency(RF)based communication per-forms better than acoustic communication and provides a data rate of up to 100 Mbps in an underwater environment.Nonetheless,due to high propagation loss,the communication range using RF is limited to a few meters.More importantly,the underwater nodes are battery-operated and recharging the bat-tery is difficult.Therefore,it is imperative that underwater RF networks are analyzed using an accurate energy model for its deployment and management.This requires that the underwater network is prop-erly modeled.In this work,a cluster-based three-dimensional(3D)architecture for underwater networks using RF communication is proposed.Importantly,the energy-based throughput of the 3D architecture using multi-hop communication,3D E-CRUSE,is obtained using a mathematical model.The throughput is then observed for various water environments,various parameters and the results are compared to the existing two-dimensional architecture.It is observed that the throughput of the proposed 3D architecture is up to 3 times more than the 2D architecture.