Usage Of Available Spectrum Research Articles

Block Allocation Strategy for Multiple Input Multiple Output (MIMO)–Orthogonal Frequency Division Multiple Access (OFDMA) System

The challenge of next generation mobile wireless networks necessitates efficient usage of available spectrum. The multiple input multiple output (MIMO)–orthogonal frequency division multiple access (OFDMA) technology exploits spatial and frequency diversity completely to maximize the usage of the limited available spectrum. The major factor that MIMO–OFDMA system proposes is allocation of interference free blocks for the arriving traffic. The author extends subsequence DPA strategy to MIMO–OFDMA system to transmit real time video traffic. The traffic and channel interference constraints are considered. The system is modeled using generalized stochastic petri nets and the analytical results are validated by simulation. The performance characteristics like mean delay and normalized throughput of subsequence DPA for various combinations are analysed. For 4 × 4 system, subsequence DPA (1, 4) and (2, 2) combinations are analyzed and it is observed that (2, 2) combination performs well than that of (1, 4) combination by 33 and 32% in terms of mean delay and normalized throughput respectively. For 8 × 8 system, subsequence DPA for (1, 8), (2, 4) and (4, 2) combinations are examined and (2, 4) and (4, 2) outperforms (1, 8) by 51 and 75% respectively in terms of mean delay and 48 and 74% respectively for normalized throughput.

Maximizing the lifetime of energy‐constrained cooperative spectrum sensing sensor network

SummaryAdding the cognitive capability to wireless sensor networks allows the sensors to monitor the spectrum and identify the spectrum holes to operate in different frequencies according to the radio environment which result in better spectrum utilization. Spectrum sensing is a main component in any cognitive radio network. In this paper, we propose a new cooperative sensing scheme based on energy detection for cognitive sensor networks which is constrained by the energy limitation of the wireless sensor elements. The proposed scheme minimizes the sensing energy for individual sensor and carefully selects the suitable participant sensors in each cooperative sensing process. This results in maximizing the lifetime of energy‐constrained wireless sensor networks. The proposed scheme also takes into consideration the constraints on the detection accuracy. The simulation results show that the proposed scheme prolonged the lifetime of the cognitive network, makes efficient usage of available spectrum by secondary users, and satisfy the target detection performance.

Optimization of Radio Resource Allocation in Energy Efficient OFDMA Systems

Background/Objectives: Proficient usage of available spectrum and energy are playing an essential role in case of wire communication as well as wireless Communications with necessitate of high data rate and superior quality. To enhance energy efficiency and spectral efficiency in OFDMA systems through effective allocation of radio resources. Methods/Statistical Analysis: Optimization problem is formulated to minimize the power consumption and maximize the energy efficiency.