Subcarrier Power Allocation Scheme Research Articles

Resource allocation for cache-enabled cloud-based small cell networks

To address the serious challenge of satisfying explosively increasing multimedia content requests from a massive number of users in mobile networks, deploying content caching in base stations to offload network traffic while satisfying content requests locally has been regarded as an effective approach to enhance the network performance. Moreover, content delivery via wireless transmissions in a cache-enabled mobile network needs to be optimized taking the proactive caching policy into consideration. Accordingly, in this paper, we investigate and propose an efficient resource allocation framework for cache-enabled cloud-based small cell networks (C-SCNs) to achieve the benefits of content caching by considering two phases, i.e., content placement and content delivery. In particular, for the content placement phase, we propose a low-complexity distributed popularity-based framework for allocating cache sizes of SBSs to popular contents, in order to offload network traffic and satisfy content requests locally. For the content delivery phase, we propose a low-complexity joint user association and subcarrier-power allocation scheme for min-rate guaranteed content delivery over orthogonal frequency division multiple access (OFDMA) based downlink transmissions. Trace-based simulations and numerical results demonstrate the effectiveness of the proposed schemes in the cache-enabled C-SCNs.

Improved power loading scheme for orthogonal frequency division multiplexing based cognitive radio

A subcarrier power allocation scheme for orthogonal frequency division multiplexing (OFDM) based cognitive users has been proposed for spectrum sharing with primary users (PU) allowing secondary users (SU) to coexist in same as well as adjacent frequency bands by underlay and interweave approaches respectively. The SU sum capacity of reliable communication has been maximised under the constraints of total power, each sub-channel power and PU aggregate interference limits. Based on the quality of channel gains and spectral distance from PU bands, the powers of subcarriers adjacent to PU bands are suitably controlled till the interference constraint of PUs are satisfied. Controlled subcarrier deactivation achieved by augmenting this ‘n-adjacent’ power redistribution step to traditional OFDM water-filling gives a powerful tool for efficiently maintaining high SU sum capacity without exceeding PU interference tolerance limit for a wide range of total power budget. Different water levels get assigned for the adjacent and non-adjacent subcarrier groups. In terms of SU capacity and PU interference, the proposed algorithm outperforms some of the existing schemes having almost same complexity as the proposed one. The improvement is significant when the adjacent subcarriers channel gains are relatively ‘good’ or ‘bad’ compared with the non-adjacent ones.

Fair subcarrier-power allocation scheme for multiuser multicarrier systems

The main objective of multiuser orthogonal frequency division multiple access (MU-OFDM) is to maximize the total system capacity in wireless communication systems. Thus, the problem in MU-OFDM system is the adaptive allocation of the resources (subcarriers, bits and power) to different users subject to several restrictions to maximize the total system capacity. In this work, a proposed subcarrier allocation algorithm was presented to assign the subcarriers with highest channel gain to the users. After the subcarrier allocation, subcarrier gain-based power allocation (SGPA) was employed for power and bit loading. The simulation results show that the proposed subcarrier-power allocation scheme can achieve high total system capacity and good fairness in allocating the resources to the users with slightly high computational complexity compared to the existing subcarrier allocation algorithms.

A low-complexity subcarrier-power allocation scheme for frequency-division multiple-access systems

A low-complexity subcarrier-power allocation scheme for frequency-division multiple-access systems

Subcarrier Power Allocation in OFDM-Based Dual-Hop Systems with AF Relaying

This letter examines the problem of allocating the subcarrier power of the relayed signal in orthogonal frequency division multiplexing (OFDM) based dual-hop systems in which the relay terminal is operated in an Amplify-and-Forward (AF) mode and the source node transmits its signal with a uniform power distribution. In AF relaying systems, both the modulation order and the error control scheme are fixed at the relay node, and thus the potential for increasing the data rate via a suitable allocation of the subcarrier power at the relay node does not exist. Therefore, this study proposes an alternative subcarrier power allocation scheme in which the objective is to scale the power assigned to each of the relayed signal sub-carriers in such a way as to minimize the equivalent average noise power at the destination terminal.