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This SpringerBrief presents a survey of dynamic resource allocation schemes in Cognitive Radio (CR) Systems, focusing on the spectral-efficiency and energy-efficiency in wireless networks. It also introduces a variety of dynamic resource allocation schemes for CR networks and provides a concise introduction of the landscape of CR technology. The author covers in detail the dynamic resource allocation problem for the motivations and challenges in CR systems. The Spectral- and Energy-Efficient resource allocation schemes are comprehensively investigated, including new insights into the trade-offs for operating strategies. Promising research directions on dynamic resource management for CR and the applications in other wireless communication systems are also discussed. Cognitive Radio Networks: Dynamic Resource Allocation Schemes targets computer scientists and engineers working in wireless communications. Advanced-level students in computer science and electrical engineering will also find this brief useful reading about the next generation of wireless communication.

Inhaltsverzeichnis

Frontmatter

1. Introduction

Abstract
Built on a software-defined radio, cognitive radio (CR) is generally defined as an intelligent wireless communication paradigm with the awareness of its environment, which is able to learn from the environment and adapt to statistical variations in the input stimuli using understanding-by-building methodology. It is proposed to achieve efficient radio spectrum utilization, as well as high reliable communication whenever and wherever needed.
Shaowei Wang

2. Dynamic Resource Allocation

Abstract
Dynamic Resource Allocation is an essential technique to exploit the time-space-frequency variation in wireless channels by adaptively distributing precious radio resources, such as spectrum and power, to either maximize or minimize the concerned network performance metrics. In traditional static resource allocation strategies, subchannels are distributed in a predetermined manner; that is, each user is assigned fixed frequency bands regardless of the channel status. In this case, the resource allocation problem reduces to power allocation or bits loading on each subchannel, which fails to fully exploit the potential of multiuser diversity in wireless environment.
Shaowei Wang

3. Spectral-Efficient Resource Allocation in CR Systems

Abstract
Spectral efficiency (SE), defined as the system throughput per unit of bandwidth, is a prevalent criterion for wireless network optimization. For instance, the peak value of SE is always taken as one of the pivotal indicators of 3rd Generation Partnership Project (3GPP) evolution for network performance. Particularly, in OFDM-based systems with a given bandwidth, dynamic resource allocation is always carried out to explore the potential system throughput by making efficient use of channel characteristics.
Shaowei Wang

4. Energy-Efficient Resource Allocation in CR Systems

Abstract
With the explosive growing demands for high data-rate wireless services, the energy consumption is also increasing at an alarming rate nowadays. Consequently, it leads to a large amount of greenhouse gas and high operation expenditure for wireless service providers. Recently, green radio is becoming increasingly important and navigates new directions for research activities, with emphasis on the energy-efficiency (EE) in wireless systems. An overview of the EE concerned in wireless communications is surveyed in, which recommends the technical roadmaps of several major international projects for energy-efficient wireless networks and investigates the state-of-the-art research on this topic. Particularly, energy-efficient RA has been put on the agenda in both industry and academia, especially for the OFDM-based systems. Different from the two conventional classes of dynamic RA in OFDM systems—rate adaptive and margin adaptive, energy-efficient RA is a special case where the objective is generally to maximize or minimize a certain metric of EE for a wireless system. The most popular one is called “bits-per-Joule”, defined as the system throughput with unit power consumption.
Shaowei Wang

5. Trade-Off Between Spectral- and Energy-Efficiency

Abstract
Spectral-efficiency (SE) and energy-efficiency (EE) serve as two vital metrics in dynamic resource allocation, which have been investigated separately in the previous chapters. Actually, SE and EE, however, do not always coincide and even conflict with each other sometimes. Such characteristic makes it impossible to achieve the optimal SE and EE simultaneously all the time. Hence, how to balance the SE and EE according to the preference of the network operator is well worth studying. In light of the fact that channel capacity scales linearly with the available bandwidth but increases logarithmically with the transmission power, it is possible to trade spectral for energy efficiency, that is, to realize energy saving while guaranteeing the desired quality of service (QoS).
Shaowei Wang
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