Kumudu S. Munasinghe

Interworked WiMAX-3G cellular data networks: An architecture for mobility management and performance evaluation

This paper proposes an architecture for interworking heterogeneous all-IP networks with an in-depth analysis of its performance. The novelty of this framework is that it freely enables any 3G cellular technology, such as the Universal Mobile Telecommunications System (UMTS) or the CDMA 2000 system, to interwork with a given broadband wireless access (BWA) system, such as the Worldwide interoperability for microwave access (WiMAX) network or the wireless local area network (WLAN) via a common signaling plane. As a universal coupling mediator for real-time session negotiation and management between these dissimilar networks, the IP multimedia subsystem (IMS) has been exploited. The analytical evaluation investigates the behavior of handoff delay, transient packet loss, jitter, and signaling cost during a vertical handoff for the given framework. Finally, an OPNET based simulation platform has been introduced for the verification of the analytical model and results.

Interworking of WLAN-UMTS networks: an IMS-based platform for session mobility

In this article a framework for interworking between a WLAN and the UMTS is presented. The uniqueness of this architecture is that the IP multimedia subsystem proposed by the 3GPP has been used as an arbitrator for network coupling and real-time session management. Apart from the advantage of a cellular network user being able to enjoy higher levels of bandwidth over a WLAN, IMS also provides a common platform for unified session control, as well as higher levels of terminal and service mobility over a heterogeneous networking environment. The article concludes by presenting the potential of this model for service continuity during and after vertical handoff with simulation results for validation.

An eco-inspired energy efficient access network architecture for next generation cellular systems

Improving energy efficiency, reducing carbon footprint and self-sustainability are key concerns in the design and development of future green communication networks. Therefore, in this paper, a novel energy efficient cellular access network architecture based on the principle of ecological proto-cooperation is proposed. Furthermore, for the first time, the wake-up technology is introduced to cellular access networks for implementing the proposed cooperative architecture. According to our proposal, base transceiver stations (BTSs) cooperatively and dynamically make intelligent decisions for switching between different power modes depending on network traffic conditions. Next, an extensive simulation process under different traffic patterns is carried out for identifying network parameters corresponding to optimal energy savings. The analysis of results reveals that the proposed architecture is capable of substantially reducing the energy consumption. In addition, as a secondary result, the proposed architecture offers an additional level of sustainability to the cellular access network infrastructure.

Distributed Inter-BS Cooperation Aided Energy Efficient Load Balancing for Cellular Networks

We propose a distributed cooperative framework among base stations (BS) with load balancing (dubbed as inter-BS for simplicity) for improving energy efficiency of OFDMA-based cellular access networks. Proposed inter-BS cooperation is formulated following the principle of ecological self-organization. Based on the network traffic, BSs mutually cooperate for distributing traffic among themselves and thus, the number of active BSs is dynamically adjusted for energy savings. For reducing the number of inter-BS communications, a three-step measure is taken by using estimated load factor (LF), initializing the algorithm with only the active BSs and differentiating neighboring BSs according to their operating modes for distributing traffic. An exponentially weighted moving average (EWMA)-based technique is proposed for estimating the LF in advance based on the historical data. Various selection schemes for finding the best BSs to distribute traffic are also explored. Furthermore, we present an analytical formulation for modeling the dynamic switching of BSs. A thorough investigation under a wide range of network settings is carried out in the context of an LTE system. Results demonstrate a significant enhancement in network energy efficiency yielding a much higher savings than the compared schemes. Moreover, frequency of inter-BS correspondences can be reduced by over 80%.

A 3GPP-IMS Based Approach for Converging Next Generation Mobile Data Networks

This paper presents a promising architecture for converging third-generation (3G) cellular data networks and wireless local area networks (WLANs) by using the IP multimedia subsystem (IMS), proposed by the 3G Partnership Project (3GPP), as an arbitrator. The IMS provides real-time session management, and unified session control. Within the scope of the presented framework, terminal and session handoffs are investigated for two different roaming scenarios. The first scenario investigates handoff from UMTS to WLAN and the second scenario investigates handoff from WLAN to UMTS. The paper concludes by presenting some simulation results obtained for these handoff scenarios using an OPNET based simulation model.

A Unified Mobility and Session Management Platform for Next Generation Mobile Networks

This paper presents a novel approach towards realizing a unified mobility and session management platform for next generation mobile networks at the core network level. In particular, this framework enables a common platform for interworking between universal mobile telecommunications system (UMTS), CDMA2000 technology, and wireless local area networks (WLANs). Within the proposed interworking architecture, the IP multimedia subsystem (IMS) is used as a universal coupling mediator for real-time session negotiation and management over a mobile IP (MIP) based IP mobility management framework. Despite numerous architectural challenges on how IMS and MIP may contribute for session management and IP mobility, the proposed framework achieves this with minimal changes to the existing standards. The paper concludes by presenting simulation results obtained for validating this model using an OPNET based model.

An analytical evaluation of mobility management in integrated WLAN-UMTS networks

Ensuring uninterrupted service continuity for handoff calls in an all-IP inter-networked heterogeneous environment requires successful session management among participating access networks. As such, a mobility-aware novel interworking architecture is presented in this article that facilitates session management including session establishment and seamless session handoff across different networks. This framework conveniently enables any 3G cellular technology such as the Universal Mobile Telecommunications System (UMTS) to interwork with a given Broadband Wireless Access (BWA) technology such as the Worldwide Interoperability for Microwave Access (WiMAX) network or the Wireless Local Area Network (WLAN) under a common signaling platform. This framework exploits the IP Multimedia Subsystem (IMS) as a universal coupling mediator for real-time session negotiation and management. Next, a Queuing Theory based analytical model for evaluating the performance of vertical handoff management between these interworked 3rd Generation (3G) cellular networks and the WLANs is presented. The analysis includes vertical handoff performance measures such as delay, transient packet loss, jitter, and signaling overhead/cost. The latter part of this paper presents some results from OPNET based simulations for the verification of the analytical model and results.

Accuracy, latency, and energy cross-optimization in wireless sensor networks through infection spreading

In this paper, cross-optimization of accuracy, latency, and energy in wireless sensor networks (WSNs) through infection spreading is investigated. Our solution is based on a dual-layer architecture for efficient data harvesting in a WSN, in which, the lower layer sensors are equipped with a novel adaptive data propagation method inspired by infection spreading and the upper layer consists of randomly roaming data harvesting agents. The proposed infection spreading mechanisms, namely random infection (RI) and linear infection (LI), are implemented at the lower layer. The entire sensor field is dynamically separated into several busy areas (BA) and quiet areas (QA). According to the BA or QA classification, the level of importance is defined, on which, the optimal number of infections for a particular observation is evaluated. Therefore, the accessed probability for observations with a relatively higher importance level is adaptively increased. The proposed mechanisms add further value to the data harvesting operation by compensating for its potential lack of coverage due to random mobility and tolerable delay, thus a relatively higher accuracy and latency requirements can be guaranteed for the optimization of energy consumption in a dynamically changing environment. Further, with the cost of processing simple location information, LI is proved to outperform RI. Copyright

A protocooperation-based sleep-wake architecture for next generation green cellular access networks

The rapidly increasing contribution towards global warming from the information communication technology (ICT) sector is a clear indication of the need for energy efficient green communication networks. For instance, in the case of cellular networks, over 80% of the total energy is consumed at the access network. On the other hand, incorporating self-sustainability and autonomy in its operation, control, and maintenance is significantly vital due to relatively larger sizes, higher complexities, and dynamic behaviors of future networks than those of current networks. In this paper, with the inspiration from the ecological principle of protocooperation, a novel energy efficient cellular access network architecture is proposed. With the adoption of the wake-up technology, base transceiver stations (BTSs) are made to protocooperate with each other to achieve higher energy efficiency within a cellular access network. Protocooperation is one of the ecological interactions by which two interacting species gain benefit through cooperation. However, this type of cooperation is not compulsory for the survival of any of these two species. To accomplish less energy consumption and higher self-sustainability at the access network, BTSs cooperatively and dynamically switch between active and sleep modes depending on the current traffic situation. The extent of self-sustainability incorporated in the proposed architecture is studied and analyzed. As per the result, our proposed architecture and algorithm are capable of achieving a significant amount of energy saving, which is an important step towards a self-sustainable green communication system.

Body Node Coordinator Placement Algorithms for Wireless Body Area Networks

Wireless body area networks (WBANs) are intelligent wireless monitoring systems, consisting of wearable, and implantable computing devices on or in the human body. They are used to support a variety of personalized, advanced, and integrated applications in the field of medical, fitness, sports, military, and consumer electronics. In a WBAN, network longevity is a major challenge due to the limitation of the availability of energy supply in body nodes. Therefore, routing protocols can play a key role towards making such networks energy efficient. In this work, we exhibit that a routing protocol together with an effective body node coordinator (BNC) deployment strategy can influence the network lifetime eminently. Our initial work shows that the variation in the placement of a BNC within a WBAN could significantly vary the overall network lifetime. This motivated us to work on an effective node placement strategy for a BNC, within a WBAN; and thus we propose three different BNC placement algorithms considering different features of available energy efficient routing protocols in a WBAN. Our simulation results show that these algorithms along with an appropriate routing protocol can prolong the network lifetime by up to 47.45%.