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In this paper, we show the effects of phase noise on the bit-error rate (BER) and average achievable rate per user performance in downlink multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) based amplify-and-forward (AF) relay systems. We derive the mathematical representation of the signal-to-interference-plus-noise ratio (SINR) per user in the presence of phase...
Random unitary beamforming (RUB) achieves multiuser diversity gain over multiple-input multiple-output (MIMO) broadcast channels with channel state information (CSI). In this paper, we optimize RUB schemes in terms of energy efficiency (EE) which is defined as "capacity/power consumption". The key idea of our approach is to derive EE-optimal number of antennas and transmit power based on...
For wearable applications, a contactless power-transfer solution is one of the required features since exposed metal contacts for battery charge could be easily corroded by moisture and sweat. There are 3 standards for the wireless power transfer (WPT): Qi [1], PMA [2] and A4WP [3]. The Qi and PMA use a similar frequency range from 100kHz to 300kHz. However, the A4WP uses a much higher frequency of...
In this paper, we consider an uplink multiuser hybrid beamforming system where an access point (AP) communicates with multiple stations (STAs) simultaneously. The performance of the uplink multiuser hybrid beamforming system depends on the effective channel which is given by the product of channel matrix and the analog beams. Therefore, to maximize the performance, we need to select the appropriate...
In the 5th generation cellular system, a large-scale cloud radio access network is one of the most promising structures for providing high quality-of-service to end users. This extended abstract presents the impact of interference on such a system. Based on stochastic geometry and probabilistic order notation, the scaling exponents of the guaranteed signal-to-interference-plus-noise ratio and the...
In this paper, we consider an alternate transmission scheme for a multiple-input multiple-output interference relay channel where multiple sources transmit their own signals to their corresponding destinations via one of two relaying groups alternately every time phase. Each of the relaying groups has arbitrary number of relays, and each relay operates in half-duplex amplify-and-forward mode. In our...
A multiuser MIMO (MU-MIMO) TDD system in which the base station (BS) uses a large scale antenna array to communicate with single-antenna mobile users is considered. We present novel schemes to estimate both large-scale and small-scale fading coefficients by uplink pilot sequences. The large-scale fading coefficients (LSFCs) are usually ignored or assumed perfectly known and almost all MIMO channel...
In this paper, considering a two-cell interfering MIMO multiple access channel (MIMO-MAC), we propose an interference alignment scheme with an efficient limited feedback and investigate the conditions for the antenna configuration. In addition, we characterize the interference leakage power caused by quantization error as a function of feedback bits. From simulation results, we demonstrate that the...
A travelling-wave photomixer was realized. The responsivity was 0.42A/W for 15µm length device. It showed a 3dB bandwidth of more than 200GHz, limited by transit-time of photo-generated carriers. Also, it showed a successful THz wave generation up to frequency range of more than 500GHz.
In this paper, we propose a linear transceiver design based on interference alignment (IA) for multiple-input multiple-output (MIMO) heterogeneous networks, which consist of overlaying macrocell and picocells. By exploiting the concept of IA, we show that the proposed transceiver design can mitigate the effect of interference efficiently. We also provide a transceiver design based on IA for additional...
This paper presents the design, fabrication and test of a very low loss phase shifter built using the wiSpry RF MEMS switched capacitor. The phase shifter covers > 360° at 1.9–2.1 GHz with an insertion loss of 1.1+/−0.6 dB over all phase states. The measured linearity shows an IIP3 > 46 dBm over all phase states. The phase shifter has a measured power handling of 1 W before any self-actuation...
In a half-duplex relaying, the capacity pre-log factor ½ is a major drawback in spectral efficiency. This paper proposes a linear precoding scheme and an alternate relaying protocol in a dual-hop half-duplex system where three relays help the communication between the source and the destination. In our proposed scheme, we consider a phase incoherent method in relays in which the source alternately...
In multicell wireless systems with insufficient frequency reuse, user transmission will suffer other-cell interference (OCI). Cell cooperation is an effective way to mitigate OCI and increase the system sum rate. An adaptive scheme for serving one user in each cell was proposed in. In this paper, we generalize that scheme by serving more than one user in each cell with adaptive zeroforcing beamforming...
The development of the antenna which has small size and broad bandwidth is the most important issue in wireless communication system. To reduce the size of an antenna, the epsilon negative (ENG) zeroth-order (ZOR) mushroom antenna which has unique property of an infinite wavelength wave at specific non-zero frequency was proposed. In this paper, the miniaturized ENG ZOR antenna having improved bandwidth...
During the last years the significance of RFID systems has increased rapidly. In fact, its use is expected to increase by a factor of twenty until 2016. Medical applications are expected to be a main cause of this development. Currently, RFID systems are primary identification systems, based on the transmission of a key number or little further information. Using new technical developements and higher...
In this paper, a dongle-type RFID PIFA (Planar Inverted F-Antenna) structure with a resonance frequency of 920 MHz is optimized taking into account the robustness against noise factors. To achieve this, a global optimum is first sought out by means of the evolution strategy and then the robust design of the optimized antenna structure is obtained by introducing the Taguchi loss function. The validity...
Sporadic network quality problems in a cellular network become prevalent after the initial rollout phase. Such problems occur in limited area of the service coverage and they are often revealed only by on-site measurement or customer feedback. Therefore, their quantitative analysis is difficult. They must therefore be solved individually under time and cost restrictions. We propose a simulation-based...
The effect of the shorting pin on an Inverted-F Antenna (IFA) was analyzed using a equivalent model to realize the best impedance matching condition. To do this, it was proved that the shorting pin can be modelled with an equivalent circuit at first. Then, the impedance characteristics of an IFA according to the locations of a shorting pin were analyzed by using the parameters in the equivalent model...
Mobile Ad-hoc Network is an infrastructure less and decentralized network which need a robust dynamic routing protocol. Many routing protocols have been proposed to accommodate the needs of communications for MANET. In this paper, we have compared the performance of traditional proactive DSDV routing protocol along with on-demand reactive routing protocols for MANET: AODV. From analysis, the On-demand...
In this paper we propose the superheterodyne receiver beamforming architecture called post-low noise amplifier RF combining (PLRC) to reduce the power consumption by using the single analog-to-digital converter (ADC). The RF chains in our proposed schemes includes the same number of the low noise amplifier (LNA) and the discrete-level phase shifters as the number of antennas followed by the single...
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