Distance Based Power Control Research Articles

Ambient Backscatter-Based Power Control Strategies for Spectrum Sharing Networks

Prior works on power control strategy need to estimate all users’ channel state information (CSI), which consumes both spectrum and time. Two efficient and low-complexity power control strategies, namely quality of experience (QoE) based power control scheme and distance based power control strategy, are proposed for an ambient backscatter based spectrum-sharing network. In the proposed power control schemes, there is no need to estimate all users’ CSI. In the QoE-based power control strategy, only the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}$ </tex-math></inline-formula> primary users with the highest priority feedback their CSI. We introduce an attenuation factor to reduce the transmit power to satisfy the interference threshold on primary users. Then, considering the short transmission distance of secondary backscatter communication and randomly distributed primary users, we propose the distance-based power control scheme, in which only the users within the backscatter distance need to feedback their CSI. Closed-form expressions for the outage probabilities of primary and secondary systems are derived over the Nakagami- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${m}$ </tex-math></inline-formula> channels under the proposed two power control strategies. The system energy efficiency are also analyzed. Simulation results are conducted to verify the analytical results. Finally, outage performance and energy efficiency of the proposed schemes are compared with that of the existing nearest- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}$ </tex-math></inline-formula> users based power control strategy. It is shown that the proposed power control strategies have lower outage probabilities and higher energy efficiency.

Distance Based Power Control for D2D Communication in LTE-Advanced Networks

Device to device communication systems places a very important role in handling both voice and data services efficiently in LTE-A networks. Power control techniques that we adopt for efficient D2D communication becomes a challenging issue. D2D and cellular signals under the same network may result in In-band Emission Interference (IEI). This degrades discovery range which result in loss of energy efficiency, throughput and hence increases the power requirement in both uplink and downlink transmissions. In this paper, a power control algorithm is introduced which greatly helps in saving power in LTE-Advanced networks for D2D communication. Power calculation mechanisms for D2D users and cellular users are shown separately. Based on mode selection, transmit and receive power requirements are evaluated to obtain the preset Quality of Service (QoS) parameters. The simulation results presented in the proposed method demonstrates the effectiveness of power consumption in LTE-Advanced networks for device to device communication.

Achieving nonzero information velocity in wireless networks

In wireless networks, where each node transmits independently of other nodes in the network (the ALOHA protocol), the expected delay experienced by a packet until it is successfully received at any other node is known to be infinite for the signal-to-interference-plus-noise-ratio (SINR) model with node locations distributed according to a Poisson point process. Consequently, the information velocity, defined as the limit of the ratio of the distance to the destination and the time taken for a packet to successfully reach the destination over multiple hops, is zero, as the distance tends to infinity. A nearest neighbor distance based power control policy is proposed to show that the expected delay required for a packet to be successfully received at the nearest neighbor can be made finite. Moreover, the information velocity is also shown to be nonzero with the proposed power control policy. The condition under which these results hold does not depend on the intensity of the underlying Poisson point process.

A Spectral Distance Based Power Control Scheme for Capacity Enhancement of OFDM Cognitive Radio

This work investigates power allocation algorithms for capacity maximization of a non-contiguous orthogonal frequency division multiplexing (NC-OFDM) based cognitive radio (CR) user coexisting with multiple active primary users (PU), under total power budget, sub-channel power and overall interference constraints. Based on the spectral distance between specific subcarriers and PU bands, the scheme allocates power among a minimum number of PU adjacent subcarriers with a water level that is different from the `far-away' subcarriers. The proposed `n-adjacent' approach is subjected to both aggregate and individual PU band interference constraint. Unlike some of the existing methods, the proposed method is capable of meeting the constraints including the contribution of `good quality' subcarriers even when they are close to PU bands. Comparison of results for a wide range of power budget shows that the improved method, using the same complexity, can achieve higher cognitive user capacity with greater power allocation efficiency.

Analytical Modeling of Ad Hoc Cognitive Radio Environment for Optimum Power Control

Radio is an emerging wireless technology that has grabbed the attention of researchers, academicians, and telecommunication industries worldwide. Recent survey reports show that unlicensed frequency bands have become overcrowded from past few years with widespread acceptance of diverse wireless technology applications whereas, licensed frequency bands are being used intermittently. To deal with the conflicts between unlicensed spectrum overuse and underutilization of licensed frequency band, Cognitive Radio technology has been evolved eventually. It allows unlicensed subscribers to access licensed subscriber frequency band with some power constraints such that minimum or no interference should be experienced by primary user and its quality of service should not be affected while sharing its spectrum with unlicensed secondary subscriber. In this paper, distance based power control scheme has been analyzed for overlay ad-hoc cognitive radio network. It is shown that algorithm provides optimum power control as long as the separation between cognitive transmitter and receiver is greater than or equals to maximum decodable radius of primary transmitter. Keywordscommunication commission (FCC), Primary user (PU), secondary User (SU), Quality of services (QoS), Cognitive Radio (CR).

On Approximating the Cognitive Radio Aggregate Interference} \IEEEaftertitletextvspace{-1\baselineskip

The aggregate interference caused on a primary receiver by Cognitive Radio (CR) nodes distrbuted uniformly in an annular region around it is investigated, assuming Rayleigh fading and path loss. By approximating the aggregate interference with that caused by the nearest CR interferer, the exact analytical moment generating function for the nearest interferer is derived for cases of no power control and distance based power control. The outage probability based on the approximation is derived, which is a tight lower bound under certain conditions.

Application of ANFIS Power Control for Downlink CDMA-Based LMDS Systems

Rain attenuation and intercell interference are two crucial factors in the performance of broadband wireless access networks such as local multipoint distribution systems (LMDS) operating at frequencies above 20 GHz. Power control can enhance the performance of downlink CDMA-based LMDS systems by reducing intercell interference under clear sky conditions; however, it may damage system performance under rainy conditions. To ensure robust operation under both clear sky and rainy conditions, we propose a novel power-control scheme which applies an adaptive neuro-fuzzy inference system (ANFIS) for downlink CDMA-based LMDS systems. In the proposed system, the rain rate and the number of users are two inputs of the fuzzy inference system, and output is defined as channel quality, which is applied in the power control scheme to adjust the power control region. Moreover, ITU-R P.530 is employed to estimate the rain attenuation. The influence of the rain rate and the number of users on the distance-based power control (DBPC) scheme is included in the simulation model as the training database. Simulation results indicate that the proposed scheme improves the throughput of the DBPC scheme.