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The objective of this paper is to maximize the secrecy rate in an untrusted relay network with imperfect channel state information (CSI). Considering bounded channel estimation error in cooperative jamming network, we optimize the power allocation for confidential and jamming signals to maximize the instantaneous secrecy rate. The upper and lower bounds of achievable secrecy rate are analyzed. The...
The Cognitive Radio (CR) is an emerging technology for modern wireless communication system that offers a great solution to scarcity of radio spectrum. The Cognitive Radio Network (CRN) is an intelligent wireless communication organization that is aware of its environment. Here, heterogeneous nodes meet spectrum sensing challenges due to the variation of transmission power, spectrum allocation and...
Cognitive Radio (CR) is novel technology which provides a great solution to genuine lack of range and radio assets in today's situation, intellectual radio offers extraordinary arrangements. Cognitive radio is a pioneering technology which has a capability to improve the effective utilization of valuable natural resources. Cognitive Radio Network (CRN) is a vital wireless communication system that...
A required feature for the next generation of wireless communication networks will be the capability to serve simultaneously a large number of devices with heterogeneous CSIT qualities and demands. In this paper, we consider the overloaded MISO BC with two groups of CSIT qualities. We propose a transmission scheme where degraded symbols are superimposed on top of spatially-multiplexed symbols. The...
Maximization of the Energy Efficiency (EE) is considered as a main objective in the design of modern wireless networks. In this paper, we address the energy efficiency enhancement of dual-hop amplify-and-forward (AF) cooperative relay systems considering imperfect statistical channel state information (CSI) over Rayleigh fading channels. We first formulate the expression of the EE. Then, based on...
In this paper, we propose a joint pilot and data power allocation scheme aiming to improve the energy efficiency of time division duplexing (TDD) massive multi-user multiple-input multiple-output (MU-MIMO) communication systems for both uplink and downlink transmission. The proposed scheme uses a maximum-ratio combining (MRC) detector in the uplink together with a maximum-ratio transmission (MRT)...
Robust adaptive modulation (AM) is a promising technique to improve the spectrum efficiency (SE) of high speed railway (HSR) communication system. Although robust AM transmission schemes with assumption of block fading channel have been extensively investigated, which are no longer valid in the fast time-varying channel due to the channel variation in frame duration. This paper investigates the optimum...
The channels in a high-speed train (HST) environment are very quickly time-varying within an OFDM symbol so it is preferable to have their estimation and symbol detection to be simultaneously implemented. Time-varying characteristics of the channels also causes unavoidable inter-carrier interferences, which make both channel estimation and symbol detection doubly difficult. Considered in this paper...
This paper considers power allocation between data and pilot symbols for an orthogonal frequency division multiplexing (OFDM) system in a high-speed train (HST) environment. The channel gains are very quickly time-varying within an OFDM symbol so both their estimation and symbol detection must be simultaneously implemented with unavoidable inter-carrier interferences. The average channel complex gains...
This paper considers a wireless-energy-transfer (WET)-enabled massive multiple-input-multiple-output (MIMO) system based on superimposed pilot (SP). With the aid of SP, the uplink (UL) channel estimation and wireless information transmission (WIT) that powered by the downlink (DL) WET can be operated simultaneously, and thus provide the potential for improving the UL achievable rate. The impact that...
In this paper, we propose a power control algorithm for uplink and downlink multi-cell massive MIMO systems, where channel estimation error, pilot contamination and correlated channels are taken into account. Moreover, a closed-form power control algorithm under the assumption of equal power allocation for multiple users is provided. The simulation results show that equal power allocation is near...
Recently, much attention has been paid to the green design of wireless communication systems using energy efficiency (EE) metrics that should capture all energy consumption sources to deliver the required data. In this paper, we formulate an accurate EE metric for cooperative two-hop systems that use the amplify-and-forward relaying scheme. Different from the existing research that assumes the availability...
In this paper, we consider superposition coding (SC) scheme in a multiple-input multiple-output (MIMO) broadcast channel when the transmitter obtains the channel state information (CSI) through user's quantized feedback. The algorithms for the base station (BS) scheduling, including users selection, power allocation among co-scheduled users, and precoding matrix assignment are investigated. We also...
Resource scheduling and power allocation for femtocell downlink when reusing regular macro-cell resources must ensure good signal quality at macrocell user equipment (MUE). This work considers the resource assignment and power allocation problem when femtocell can overhear the channel quality indicator (CQI) report from the MUE to its serving macro-base-station (MBS). Considering two different channel...
This paper investigates the effect of channel estimation errors on the capacity of full-duplex amplify-and-forward relay networks. We first derive the lower bound of the capacity in the presence of channel estimation errors and residual self-interference due to full-duplex relaying. Accordingly, the optimal power allocation schemes in maximizing the capacity with joint power constraints are proposed...
Bit error rates (BERs) for amplify-and-forward (AF) relaying systems with two different pilot-symbol- aided channel estimation methods, disintegrated channel estimation (DCE) and cascaded channel estimation (CCE), are derived in Rayleigh fading channels. Based on these BERs, the pilot powers at the source and at the relay are optimized when their total transmitting powers are fixed. Numerical results...
In this paper, we describe a guideline of pilot sequence design for multi-channel estimation using uplink DMRS of LTE-A in the partial co-channel resource allocation. In the D2D or small cell system the partial co-channel environment can be frequently occurred, and thus multi-channel estimation is required for interference mitigation. We consider three methods with uplink DMRS for channel estimation...
We use a per-path Rician fading model to analyze the capacity of acoustic channels, and provide experimental data to confirm the practicality of simulation results. Three power allocation policies are considered: water-filling, uniform power allocation across selected, channel-favored frequencies (“on-off” carriers in an OFDM system), and uniform power allocation across all carriers irrespective of...
This work investigates the impact of power allocation for channel estimation (CE) in spatial modulation (SM). SM is a unique single-stream multiple-input multiple-output (MIMO) transmission technique that achieves spatial multiplexing gains. While SM completely avoids inter-channel interference, a single active antenna leads to a challenge for CE, i.e., all transmit antennas have to be activated sequentially...
In the current literature considering multi-cell multi-user massive multiple-input multiple-output (MU-Massive-MIMO) systems, equal uplink power allocation among users is typically assumed, which does not exploit the potential of peruser power control. By contrast, in this paper we apply multi-cell uplink power control, assuming the minimum mean-square-error receiver based on the pilot contaminated...
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