Md. Farhad Hossain

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 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.

On the energy efficiency of self-organizing LTE cellular access networks

Energy efficiency and self-organizing network architectures are the top issues for future cellular systems. In this paper, we propose an energy saving self-organizing access network architecture for long term evolution (LTE) cellular systems. Self-organizing nature is attained through intelligent cooperation among the evolved node Bs (eNBs) communicating via X2 interface in the LTE evolved UMTS terrestrial access network (E-UTRAN). Using the proposed coordination and cooperation, the E-UTRAN is dynamically reconfigured in real-time utilizing minimum number of active eNBs and switching the redundant eNBs into sleep mode. System performance under different network scenarios, cell layouts and eNB power consumption profiles is evaluated. Simulation results indicate a substantial drop in the networks energy consumption. In addition, the network becomes more efficient in utilization of its available capacity.

Two level cooperation for energy efficiency in multi-RAN cellular network environment

In this paper, by exploiting the availability of multiple cellular radio access networks (RANs), we propose a novel two-level cooperative access network framework for superior energy efficiency. Geographically co-located RANs mutually cooperate each other through the combined use of base transceiver station (BTS) level intranetwork cooperation and RAN level internetwork cooperation. By jointly applying the two types of cooperation, BTSs within individual RAN as well as BTSs of several RANs communicate and intelligently cooperate for dynamically minimizing the number of active BTSs and thus reduce energy utilization at the access network level. Extensive simulations are carried out for exploring the degree of energy savings and sleeping patterns of BTSs of each cooperating RANs as well as that of the combined network. Simulation results show that through the proposed joint cooperation, each cooperating RAN gains substantial economical benefits by significantly reducing its energy expenditure. Furthermore, comparison with the cases of intranetwork and internetwork cooperation acting alone reveals that by participating in the joint cooperation, each RAN can achieve much higher energy savings.

Ecological competition based resource control for sustainable heterogeneous wireless networks

In a heterogeneous wireless network (HWN), users from multiple networks with various QoS requirements compete with each other for finite resources. As this competition becomes intense, the distribution of resources may become extremely haphazard, thus making users of certain classes to be disadvantaged over others. This may destabilize the HWNs and even lead certain classes of users requiring relatively higher resources into complete extinction. Hence, the key for a sustainable HWN is a resource management scheme, which fairly allocates all network resources. Therefore, in this paper, first we propose an analytical model to characterize such unfairness and instability in HWNs. This approach is based on the theory of ecological multi-species multi-resource competition (MSMRC). Next, to counter the aforementioned instability and unfairness, we propose a new joint radio resource management (JRRM) scheme, MSMRC scheme, which is capable of ensuring the HWNs stability and maintain the coexistence of users of widely diverse requirements, even under the extreme situations. Results indicate that the MSMRC scheme also supports the sustainability of the HWN by helping it to withstand sudden disruptions.

PV-Powered CoMP-Based Green Cellular Networks with a Standby Grid Supply

This paper proposes a novel framework for PV-powered cellular networks with a standby grid supply and an essential energy management technique for achieving envisaged green networks. The proposal considers an emerging cellular network architecture employing two types of coordinated multipoint (CoMP) transmission techniques for serving the subscribers. Under the proposed framework, each base station (BS) is powered by an individual PV solar energy module having an independent storage device. BSs are also connected to the conventional grid supply for meeting additional energy demand. We also propose a dynamic inter-BS solar energy sharing policy through a transmission line for further greening the proposed network by minimizing the consumption from the grid supply. An extensive simulation-based study in the downlink of a Long-Term Evolution (LTE) cellular system is carried out for evaluating the energy efficiency performance of the proposed framework. System performance is also investigated for identifying the impact of various system parameters including storage factor, storage capacity, solar generation capacity, transmission line loss, and different CoMP techniques.

On the eNB-based energy-saving cooperation techniques for LTE access networks

Energy efficiency is one of the top priorities for future cellular networks, which could be accomplished by implementing cooperative mechanisms. In this paper, we propose three evolved node B eNB-centric energy-saving cooperation techniques for long-term evolution LTE systems. These techniques, named as intra-network, inter-network, and joint cooperation, involve traffic-aware intelligent cooperation among eNBs belonging to the same or different networks. Our proposed techniques dynamically reconfigure LTE access networks in real time utilizing less number of active eNBs and thus, achieve energy savings. In addition, these techniques are distributed and self-organizing in nature. Analytical models for evaluating switching dynamics of eNBs under these cooperation mechanisms are also formulated. We thoroughly investigate the proposed system under different numbers of cooperating networks, traffic scenarios, eNB power profiles, and their switching thresholds. Optimal energy savings while maintaining quality of service is also evaluated. Results indicate a significant reduction in network energy consumption. System performance in terms of network capacity utilization, switching statistics, additional transmit power, and eNB sleeping patterns is also investigated. Finally, a comprehensive comparison with other works is provided for further validation. Copyright

Spectrum of Disease and Prescription Pattern for Outpatients with Neurological Disorders: An Empirical Pilot Study in Bangladesh

Background: Neurological disorders represent one of the most prominent causes of morbidity and mortality that adversely affect the lifestyle of patients and a major percentage of these diseases exists in developing countries. Purpose: The objective of this study was to examine the prevalence and prescription pattern for outpatients with neurological disorders in Bangladesh. Methods: The study was conducted on 1,684 patients in 6 hospitals (National Institute of Neurosciences and Hospital, Dhaka Medical College and Hospital, Bangabandhu Sheikh Mujib Medical University, Shaheed Suhrawardy Medical College, Sir Salimullah Medical College, and Apollo Hospitals Dhaka) of the Dhaka City from March 2014 to June 2015. Data were collected through a predesigned questionnaire from the patients that contain information about gender, age, marital status, occupation, residential status, affected disease, self-medicated medicines, and prescribed medicines. Results: Out of 1,684 patients, 28.38% patients were aged 51–60 years and male, 57.19% predominance. The study exposed headache and migraine for 29.75% patients, followed by stroke for 23.93% patients and seizure for 7.07% patients. Genetic reason for the neurological disorders was seen only among 12.35% patients. In this study, 16.98% patients had been affected by neurological disorders for more than 2 years and 19% of patients for less than 6 months. Most extensively prescribed medicines were multivitamins and multiminerals used by 17.89% of patients followed by nonsteroidal anti-inflammatory drugs and other analgesic by 14.84%; afterwards antiulcerants were used by 12.62%, subsequently anticoagulants were used by 11.61% followed by antihyperlipidemic medicines by 10.26% and antiepileptic drugs by 8.08% of patients. The crucial reasons for the selection of prescribed medicines were the confidence that patients had with the physician’s prescribed medicines, which was shown for 40.97% patients and knowledge of the medicines was reported for 35.04% patients. The period of prescribed medicine usage was 1–3 months for 39.73% patients and 3–6 months for 29.16% patients. The patient’s compliance for prescribed medicines was satisfactory for 34.56% patients, good for 28.15% patients, and side effects were reported for 23.22% patients. Conclusion: In Bangladesh, it is not surprising to note that neurological diseases are more prevalent than other different diseases among different age groups and genders. Headache and migraine, stroke and seizure are most frequently encountered neurological disorders here. Treatment procedure of these disorders is not quite suitable due to the anomalies of health care management systems. Appropriate management of the health care system, especially the placement of hospital and community pharmacy can overcome the existing inconsistencies as well as increase the knowledge, awareness, and perception of the patients about health and neurological disorders.

Traffic-aware two-dimensional dynamic network provisioning for energy-efficient cellular systems

Conventional peak-traffic-based provisioning of cellular mobile networks leads to a significant wastage of electrical energy. Therefore, we propose a novel traffic-aware two-dimensional dynamic network provisioning mechanism for enhancing the energy efficiency in orthogonal frequency division multiple access OFDMA-based cellular systems. Proposed scheme, named as joint dynamic sectorisation and switching of base station BS, adaptively provisions cellular access networks by switching the redundant BSs as well as sectors into sleep mode. Quality of service, namely, user data rate, service continuity and network coverage, is also maintained. Because of the high complexity of the formulated generalised energy optimisation problem, the two dimensions i.e. sector switching and BS switching are decoupled in time-domain into two sub-problems, each executing its own heuristically guided algorithm. Moreover, a novel exponentially weighted moving average EWMA-based load factor estimator is employed for reducing the occurrence of network provisioning. System performance is evaluated using extensive simulations demonstrating substantial energy savings. In addition, impact on the spectral efficiency and resource utilisation is presented. Effectiveness of joint dynamic sectorisation and switching of BS is further validated by comparing with the individual application of sectorisation and BS switching. Furthermore, for realistic traffic patterns, use of EWMA estimator achieves over 40% reduction in network provisioning events without compromising energy-saving performance. Copyright