Abstract
The rapid development of modern communication services results in high data rate requirements from the end user. It is challenging to meet high data rate requirements because of prevailing issues such as spectrum scarcity and spectrum underutilization due to fixed spectrum assignment policy. Cognitive Radio (CR), being the enabler of dynamic spectrum management techniques, has the capability to tackle these issues by proficiently implementing spectrum sharing schemes using Multicarrier Modulation (MCM) techniques. In CR system, where the Primary User (PU) and the Secondary User (SU) co-exist in the same frequency band, mutual interference (i.e., from SU to PU and vice versa) is a limiting factor on the achievable capacity of both the PU and the SU. Power allocation in MCM based CR systems aims to dynamically control the transmit power on each subcarrier of the SU in order to reduce the mutual interference. Furthermore, combining multiple antennas with MCM is regarded as a very attractive solution for the CR communications to effectively enhance data rate without demanding additional bandwidth and transmit power.
Highlights
Radio spectrum is a scarce resource and its demand is growing rapidly to meet high data rate end user demands
Cognitive Radio (CR) offers a solution to the spectrum underutilization problem by proficiently implementing spectrum sharing schemes using Multicarrier Modulation (MCM) techniques
Orthogonal Frequency Division Multiplexing (OFDM) system is the most popular transmission scheme and the availability of low cost chip sets makes it potential candidate for CR systems, Filter Bank Multicarrier (FBMC) outperforms OFDM in terms of channel capacity due to better signaling shape
Summary
Radio spectrum is a scarce resource and its demand is growing rapidly to meet high data rate end user demands. Filter Bank Multicarrier (FBMC) system achieves higher spectral efficiency due to the fact that CP is no longer needed It offers full control over spectral leakage as a result of its improved spectral shape at a cost of higher implementation complexity and latency compared to OFDM systems [3]. The amount of interference introduced by the SU subcarriers into the PUs band depends on three factors, i.e., power allocated in that subcarrier, spectral distance between that particular subcarrier and the PUs band, and location of the PU (whether it is detectable or not by the SU) To address this issue, different power allocation schemes have been proposed in the literature where Gaussian inputs are assumed to maximize the SU data rate for a given interference threshold values [4,5]. Gaussian optimized power results in a reduced transmission rate due to extra allocated power causing nulling of more subcarriers compared to the optimal power under the FSA input
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