Heterogeneous networks using a mix of macrocells and small cells are foreseen as one of the solutions to meet the ever increasing mobile traffic demand. Nevertheless, a massive deployment of small cell access points (SAPs) leads also to a considerable increase in energy consumption. Spurred by growing environmental awareness and the high price of energy, it is crucial to design energy efficient wireless systems for both macrocells and small cells. In this work, we evaluate a distributed sleep-mode strategy for cognitive SAPs and we analyze the trade-off between traffic offloading from the macrocell and the energy consumption of the small cells. Using tools from stochastic geometry, we define the user discovery performance of the SAP and derive the uplink capacity of the small cells located in the Voronoi cell of a macrocell base station, accounting for the uncertainties associated with random position, density, user activity, propagation channel, network interference generated by uncoordinated activity, and the sensing scheme. In addition, we define a fundamental limit on the interference density that allows robust detection and we elucidate the relation between energy efficiency and sensing time using large deviations theory. Through the formulation of several optimization problems, we propose a framework that yields design guidelines for energy efficient small cell networks.
Related Content
Energy efficiency is a subtle concept: fundamental trade-offs for cognitive radio networks
This article discusses the implications of facilitating higher energy efficiency in cognitive radio networks from the perspective of fundamental trade-offs (i.e., what needs to be sacrificed to be energy-efficient). These trade-offs are identified as QoS, fairness, PU interference, network archit...


Interference alignment for spectral coexistence of heterogeneous networks
The coexistence of heterogeneous networks within the same spectrum for enhancing the spectrum efficiency has attracted large interest lately in the research community. Furthermore, the research interest towards the deployment of small cells and multibeam satellites is increasing due to high capac...
Interference Mitigation in CR-Enabled Heterogeneous Networks
The heterogeneous network (HetNet), which deploys small cells such as picocells, femotcells, and relay nodes within macrocell, is regarded as a cost-efficient and energy-efficient approach to resolve increasing demand for data bandwidth and thus has received a lot of attention from research and i...


Scheduling and routing methods for cognitive radio sensor networks in regular topology
Wireless sensor network of regular topology is efficient in area covering and targets locating. However, communications with fixed channels lead to low spectrum efficiency and high probability of conflicts. This paper proposes economical timeslots-and-channels allocation methods for scheduling li...
Dynamic spectrum access in cognitive radio networks with RF energy harvesting
Spectrum efficiency and energy efficiency are two critical issues in designing wireless networks. Through dynamic spectrum access, cognitive radios can improve the spectrum efficiency and capacity of wireless networks. On the other hand radio frequency (RF) energy harvesting has emerged as a prom...

Joint Optimization of Clustering and Cooperative Beamforming in Green Cognitive Wireless Networks
We investigate the trade-off between performance and energy efficiency in cooperative cognitive underlay systems. By cooperating, cognitive base stations mitigate the interference and serve their users more effectively at the cost of spending more power. With a flexible cooperation scheme, we thu...
Energy and throughput efficient cooperative spectrum sensing in cognitive radio sensor networks
The sensing-throughput trade-off and the sensing-energy trade-off for cooperative spectrum sensing have been the subject of recent research. Two important, but often conflicting, design objectives for low-power devices are throughput and energy efficiency. These have not been comprehensively inve...

Energy-efficient user association in cognitive heterogeneous networks
Due to the ever increasing data traffic demands, which are directly connected to increased energy consumption, it becomes challenging for operators to achieve capacity enhancement while limiting their electric bill. To that end, exploiting the context awareness of future cognitive networks is exp...
On the Trade-Off Between Security and Energy Efficiency in Cooperative Spectrum Sensing for Cognitive Radio
Cooperative spectrum sensing is envisaged to increase reliability in cognitive radio networks. Several users cooperate to detect the availability of a wireless channel. In this framework, some malicious users may affect the decisions taken by the cognitive users by providing false information, in...

Reliable energy-efficient spectrum management and optimization in cognitive radio networks: how often should we switch?
Spectrum handoff is a promising spectrum management approach that enables the secondary user to continue its transmission by switching to a sensed-as-idle channel when the current channel is re-occupied by the primary user. Periodic sensing is commonly employed to facilitate spectrum handoff by i...