Resource-Aware Routing Algorithms for Multi-hop Cellular Networks

Wireless cellular networks are large-scale networks in which asymptotic capacity investigation is no longer a cliche. A substantial body of work has been carried out to improve the capacity of cellular networks by introducing ad hoc communications, resulting in the so-called multihop cellular networks. Most of the previous research allows ad hoc transmissions between certain source and destination pairs to alleviate base stations' relay burden. However, since reports show that Internet data traffic is becoming more and more dominant in cellular networks, we explore in this paper the capacity of multihop cellular networks with all traffic going through base stations and ad hoc transmissions only acting as relay. We first investigate the capacity of regular multihop cellular networks where both nodes and base stations are regularly placed. By fully exploiting the link rate variability, we find that multihop cellular networks can have higher per-node throughput than traditional cellular networks by a scaling factor of log 2 n. Then, for the first time we extend our study to the capacity of heterogeneous multihop cellular networks where nodes are distributed according to a general Inhomogeneous Poisson Process and base stations are randomly placed. We show that under certain conditions multihop cellular networks can also outperform traditional cellular networks by a scaling factor of log 2 n. Moreover, both throughput-fairness and bandwidth-fairness are considered as fairness constraints for both kinds of networks.

Multi-hop heterogeneous cellular networks (MHCNs) consist of conventional macro cellular networks overlaid with an irregular deployment of low-power base stations (BSs), where the communication between BSs and mobile users can be established through a single hop or multiple hops. By modeling different kinds of randomly located BSs as K tiers of independent homogeneous Poisson Point Processes, we first explore the capacity of downlink MHCNs and derive the expression of capacity under Rayleigh fading channels. Particularly, the capacity gain achieved by cell splitting and multi-hop relaying is quantified for the first time. We then study the effects of BS density, transmit power, and signal-to-interference-plus-noise-ratio (SINR) threshold on the capacity of MHCNs. More importantly, we obtain the spectral efficiency enhancement condition under which the increase of BS density and transmit power improve the spectral efficiency, thereby enhancing the capacity. One interesting observation is that at a given SINR threshold, the capacity increases with BS density when all the tiers have the same SINR threshold. Moreover, the capacity of some special networks (i.e., heterogeneous cellular networks, multi-hop cellular networks, and conventional cellular networks) are derived directly by specializing some system parameters in our results. Finally, numerical studies and simulations are conducted to validate our analysis.

Multihop cellular networks (MCNs) have been proposed as a throughput enhancement alternative for traditional cellular networks. In MCNs, as opposed to traditional cellular networks, both the base station (BS) and the mobile stations (MSs) play a significant role in forwarding data. In this paper, we propose an efficient routing protocol for single interface MCNs and compare it with an existing routing protocol. The primary motivation for exploring this single interface mechanism is to provide low cost and low power consumption mobile devices. Since pricing in packet-based data traffic for MCNs is a key issue which is not addressed so far, we proposed a set of incentive-based pricing schemes for packet based traffic that are not bound by mobility or load constraints. We also suggest reimbursement based schemes that take into account the retransmission attempts made by the intermediate nodes. We compare our routing protocol single interface MCN routing protocol (SMRP) with base driven multihop bridging protocol (BMBP) and study a set of incentive-based pricing schemes for data traffic in MCNs using extensive simulation using GloMoSim.

Multi-hop cellular networks: Architecture and protocols for best-effort and real-time communication

Nowadays, many advanced are developed and become available for users. So, the demand for a higher data rate wireless access significantly increases. For that reason, new cellular wireless networks have been introduced such as Worldwide Interoperability for Microwave Access (WiMAX), Long Term Evolution (LTE) and LTE‐advanced. However, the centralized topology of these technologies requires that the users have a direct connection to the Base Station (BS). Such topology suffers from congestion problem when a large number of users are communicating in the same time. To overcome the congestion problem, the Device‐to‐device and the mobile relays communications have been proposed to overcome the limitations of the conventional cellular architecture. These technologies can improve the cellular network capacity and reduce the infrastructure costs. However, security in multi‐hop cellular networks (MCNs) is a great challenge especially when other mobile nodes participate in the routing process. Existing works on this topic focus on ensuring security for routing information. However, most studies do not secure the data transmission after the route selection and do not simultaneously ensure all the security requirements. In this paper, we propose a new secure and reliable routing protocol for MCNs. The main objective of this protocol is to select only the trustworthy intermediate nodes to participate in the route construction. These trustworthy nodes perform the route discovery process in a secure way and so discover a secure path that does not contain any attacker as an intermediate node. The intermediate nodes of the selected route participate in establishing a group key. This key is used to secure the data transmission phase after route selection. To achieve anonymity, the BS assigns to each mobile that participates in the selected route a temporary identity. We evaluate our proposed protocol in terms of security using AVISPA tool, and we conduct some simulations using Network Simulator (NS‐2). The simulation results show that it is reliable and provides acceptable performance in terms of throughput, end‐to‐end delay and normalized routing load. Copyright © 2016 John Wiley & Sons, Ltd.

In this paper, we present a prototype for a new architecture, MCN (Multihop Cellular Network) implemented over a wireless LAN platform. MCN preserves the virtue of traditional single-hop cellular networks where the service infrastructure is constructed by many BSs (Base Stations) but it also adds the flexibility of ad hoc networks where wireless transfer through mobile stations in multiple hops is allowed. MCN can reduce the number of required BSs or improve the throughput performance. In the prototype of MCN, a bridging protocol, BMBP (Base-driven Multihop Bridging Protocol) runs between mobile stations and access points to enable multihop routing and roaming. Demonstration show that MCN is a feasible architecture for wireless LANs.

Recently, the notion that a logical next step towards future mobile radio networks is to introduce multihop relaying into cellular networks, has gained wide acceptance. Nevertheless, due to the inherent drawbacks of multihop relaying, e.g., the requirement for extra radio resources for relaying hops, and the sensitivity to the quality of relaying routes, multihop cellular networks (MCNs) require a well-designed radio resource allocation strategy in order to secure performance gains. In this paper, the optimal radio resource allocation problem in MCNs, with the objective of throughput maximization, is formulated mathematically and proven to be NP-hard. Considering the prohibitive complexity of finding the optimal solution for such an NP-hard problem, we propose an efficient heuristic algorithm, named integrated radio resource allocation (IRRA), to find suboptimal solutions. The IRRA is featured as a low-complexity algorithm that involves not only base station (BS) resource scheduling, but also routing and relay station (RS) load balancing. Specifically, a load-based scheme is developed for routing. A mode-aware BS resource-scheduling scheme is proposed for handling links in different transmission modes, i.e., direct or multihop. Moreover, a priority-based RS load balancing approach is presented for the prevention of the overloading of RSs. Within the framework of the IRRA, the above three functions operate periodically with coordinated interactions. To prove the effectiveness of the proposed IRRA algorithm, a case study was carried out based on enhanced uplink UMTS terrestrial radio access/frequency-division duplex with fixed RSs. The IRRA is evaluated through system level simulations, and compared with two other cases: 1) nonrelaying and 2) relaying with a benchmark approach. The results show that the proposed algorithm can ensure significant gains in terms of cell throughput

In a multihop cellular network, mobile terminals are able to transmit directly to other mobile terminals allowing them to lower their maximum transmission power and use other terminals as relays to forward traffic towards the base station. However, a large amount of interference is created near the base station because all traffic either emanates or is destined to the base station making it the capacity bottleneck of the network. In an autonomous infrastructure multihop cellular network, certain mobile terminals that have a connection to the backbone network act as access points and send traffic directly onto the backbone network, as would a base station. This reduces the amount of traffic required to be handled by the base station and increases network capacity. However, access points will require transmission parameters like their pilot power to be adjusted autonomously to optimal levels. In this paper, we propose an autonomous pilot power protocol that can be used by both access points and base stations. Our simulation results show that by adjusting a parameter within the pilot power protocol, a required percentage of covered terminals can be achieved by the network without prior knowledge of the location or density of terminals. Furthermore, the pilot power protocol determines the pilot power level which is optimal in terms of SINR and power consumption that achieves the required coverage while effectively eliminating the capacity bottleneck that existed at the base station.

Applying peer-to-peer communications in cellular networks to improve performance has been an active research area in recent years. Cooperation among nodes is an important prerequisite for the success of the multi-hop cellular networks. Cost savings and service availability are the primary concerns that the network provider adopts multi-hop cellular networking technology. In this paper, we present a dynamic incentive pricing scheme to maximize the revenue of the network provider. The proposed scheme adjusts the price of the feedback incentives based on the network conditions to influence the relaying capability of the network and therefore increases the revenue of the network provider. The simulation results demonstrate that the revenue can be increased by dynamically adjusting the price of the incentives for relaying services. Moreover, the proposed pricing scheme results in more revenue but does not cause higher new call blocking probability in multi-hop cellular networks.

In this paper, using the concept of capacity regions, an algorithm for joint rate allocation and routing scheme is proposed in order to maximize the total throughput of multihop cellular CDMA networks. The notion of infeasibility factor is defined and used to propose an adaptive scheme on top of the above algorithm to manage fundamental coverage-capacity tradeoff for the downlink. In fact, the output of our algorithm is the joint rate allocation, routing scheme and base station (relay) assignment which in conjunction with the proposed adaptive scheme leads to implementing the concept of cell breathing via allocating proper transmit powers to base stations and relays. We show that our optimization problem can be mapped to a multidimensional multichoice knapsack problem (MMKP). Since MMKP is NP-hard, a polynomial-time heuristic algorithm is then developed to solve our MMKP.

In recent years, device-to-device (D2D) communication has attained significant attention in the research community. The advantages of D2D communication can be fully realized in multi-hop communication scenario. The integration of cellular and multi-hop networks not only provides guaranteed quality of service and reliability as a traditional cellular network, but also has the flexibility and adaptability as a multi-hop network. Routing in such multi-hop cellular D2D networks is a critical issue, since the multi-hop network can perform worse than a traditional cellular network if wrong routing decisions are made. This is because routing in these multi-hop networks needs to take care of the node mobility, dynamic network topology, and network fragmentation, which did not exist in traditional cellular networking. This paper provides a comprehensive survey of routing in multi-hop D2D networks. Some future research directions for the routing in D2D networks are also discussed at the end of this paper.

Next generation communication networks will comprise third-generation (3G) cellular and multi-hop ad hoc networks. The paper has evaluated the end-to-end performance of TCP over a multi-hop cellular network that comprises the enhanced universal mobile telecommunications system (UMTS), namely, HSDPA and the IEEE 802.11 ad hoc networks for bulk data transfers under different HSDPA radio channel quality as well as number of hops. The throughput simulation results show that bottleneck of the multi-hop cellular network shifted between the UMTS/HSDPA network and the ad hoc network based on the different channel quality and number of hops. Ad hoc network can increase the service range of cellular network, and also improve the performance for the end-user who experiences bad channel conditions. Moreover, the relation between HSDPA radio channel usage and end-to-end user experience under different network configurations and channel conditions is also revealed. Our result can be used to select optimal routes and system performance optimization.

In a conventional cellular network, a terminal receives signals not only from the base station of that cell, but also from other cell base stations. This inter-cell interference has more impact on the cell-edge users, in multi cell environment. The inter-cell interference degrades the performance of wireless systems. Using Base Station Cooperation, the ability of a mobile station to receive signals from multiple base stations can be utilized as an opportunity to improve the spectral efficiency and to get higher data rates for cell edge users. In multi cell environment using base station cooperation overall interference can be minimized marginally, whereas the interference within the cooperation region is largely reduced. This leads to a question whether it is worth doing cooperation all the time. However increase in terms of throughput may not always be enough to increase the throughput of each of the user .Hence for such a scenario the distinct cooperation scheme is used. The distinct cooperation is a joint transmission scheme in which the selection criterion is based on user’s signal to interference plus noise ratio (SINR) is proposed and the capacity achieved through cooperation is shared equally among the cell-edge users. Here we will analyze the normal operation, full cooperation and distinct cooperation scheme in the downlink environment for cell edge users in cellular network and we will compare and see which method improves the user capacity and data rate.KeywordsCooperative transmissionfull cooperationDistinct cooperationsignal to interference plus noise ratio (SINR)

The integrated multi-hop cellular data network (IMCDN) is a hybrid wireless network architecture to overlay a special self-organized multi-hop network on an existing cellular network. The self-organized network is a multiple-layer access network that uses hierarchical-routing for data transmissions from and to mobiles. This architecture seeks to reduce the network congestion and to improve the performance of wireless data services via load balancing among layers. In this paper, we present an optimum hierarchical routing strategy with low complexity which employs a sophisticated layer-scheduling algorithm based on the load-balancing objective. The simulation results show that the developed layer scheduling algorithm achieves indeed the perfect load balancing for networks with various traffic properties.

This paper explores the fundamental downlink performance limits of multicell networks when cooperation is allowed between all the base station in the network. Toward this end, we infer the asymptotic sum rate of a capacity-achieving technique (known as dirty paper coding) for the broadcast channel in the limit of a large number of transmit antennas and single-antenna users. The users have unequal SNRs characterized by a doubly-regular gain matrix and we show that this condition can be satisfied in a finite cellular network of hexagonal cells where users are placed on corners of hexagons centered on the bases. Under this placement, we can compute the asymptotic rate per user when dirty paper coding is used across base stations in a coordinated network. We extend the analysis to an infinite coordinated network and show that its performance is lower-bounded by that of a single isolated cell. Performance comparisons are also made with conventional cellular networks where coordination among bases is not allowed.