Wireless relay (Engineering) Research Papers (original) (raw)

This paper presents the overall design of Home automation system with low cost and wireless system. Home automation plays an important role in our daily life. Home automation saves money, time and it also reduces labour work. Home automation system is advantageous for old aged and handicapped person. The standard of living at home is also improved by smart home concept. The switch mode and voice mode are used to control the home appliances. The video feedback is received in the android application which streams the video of IP Camera. This paper presents the main control system which implements the wireless technology and this technology provides remote access from android phones. The design remains the existing electrical switches and provides more safety control on the switches with low voltage activating method. The switches status is synchronized in all the control system whereby every user interface decodes the real time existing switches status. This system is designed to control electrical appliances and devices in house with low cost and ease of installation. The system designed in this paper is user friendly.

- by and +2
- •
- Homeland Security, Home automation, Wireless relay (Engineering), Arduino

This paper presents the design and implementation of a Human Interface for a housekeeper robot. It bases on the idea of making the robot understand the human needs without making the human go through the details of robots work, for example, the way that the robot implements the work or the method that the robot uses to plan the path in order to reach the work area. The interface commands based on idioms of the natural human language and designed in a manner that the user gives the robot several commands with their execution date/time. As a result, the robot has a list of tasks to be doneon certain dates/times. However, the robot performs the tasks assigned to it without any human intervention and then gives feedback to the human about each task progress in a dedicated list. As well as, the user decides to get the feedback either through the interface, through the wireless communication, or both of them. Hence, the user's presence not necessary during the robot tasks execution.

Indian economy is mainly based on agriculture. The most important parameter for the agriculture is timely and sufficient supply of water. Most of the farmers are dependent on electric water pumps for irrigation which demands electricity. The frequent, intermittent, low voltage supply of power to the agriculture sector has caused problems to the farmers who are spending their time monitoring the supply of power without which their work cannot start. In this paper we will be focussing on implementing the switching of the motor used for irrigation purposes in rural India using the technology X-bee/Zigbee trans receiver and Relay Drivers.

- by Bhuwam Dixit
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- Communication, Wireless Communications, Telecommunications, Wireless Sensor Networks

Massive multiple-input multiple-output (MIMO) avails of simple transceiver design which can tackle many drawbacks of relay systems in terms of complicated signal processing, latency, and noise amplification. However, the cost and circuit complexity of having one radio frequency (RF) chain dedicated to each antenna element are prohibitive in practice. In this paper, we address this critical issue in amplify-and-forward (AF) relay systems using a hybrid analog and digital (A/D) transceiver structure. More specifically, leveraging the channel long-term properties, we design the analog beamformer which aims to minimize the channel estimation error and remain invariant over a long timescale. Then, the beamforming is completed by simple digital signal processing, i.e., maximum ratio combining/maximum ratio transmission (MRC/MRT) or zero-forcing (ZF) in the baseband domain. We present analytical bounds on the achievable spectral efficiency taking into account the spatial correlation and imperfect channel state information at the relay station. Our analytical results reveal that the hybrid A/D structure with ZF digital processor exploits spatial correlation and offers a higher spectral efficiency compared to the hybrid A/D structure with MRC/MRT scheme. Our numerical results showcase that the hybrid A/D beamforming design captures nearly 95% of the spectral efficiency of a fully digital AF relaying topology even by removing half of the RF chains. It is also shown that the hybrid A/D structure is robust to coarse quantization, and even with 2-bit resolution, the system can achieve more than 93% of the spectral efficiency offered by the same hybrid A/D topology with infinite resolution phase shifters.

- by George Alexandropoulos
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- Millimeter Waves, MIMO Systems, Wireless relay (Engineering), Correlation

This paper proposes a new modulation method for an uncoded cognitive transmission (secondary user transmission) in presence of a Primary User (PU) for AWGN and time-varying flat-fading channels. Interference symbol of the PU is assumed to be known at the transmitter of the Cognitive User (CU) beforehand. Based on this knowledge and using a symbol by symbol approach, we design a CU modulation which can fulfill the coexistence conditions of the CU and the PU. The proposed method is a low-complexity modulation approach in a single (complex-valued) dimension rather than a high dimensional coding scheme, but still it achieves good performance. The robustness of the method is also investigated in case of having an imperfect knowledge about the PU transmitted symbols. An implementation algorithm for our modulation method is presented and its performance is evaluated by experiments.

This paper proposes a new modulation method for
an uncoded cognitive transmission (secondary user transmission)
in presence of a Primary User (PU) for the AWGN channel.
Interference of the PU is assumed to be known at the transmitter
of Cognitive User (CU) non-causally. Based on this knowledge,
for the design of the modulator and demodulator of the CU,
a symbol by symbol approach is studied which can fulfill the
coexistence conditions of the CU and the PU of the band. In this
scheme, the modulator and demodulator of CU are designed
jointly by solving an optimization problem to mitigate the
interference of the PU and minimize the symbol error probability
(Pe) in CU’s communication link without increasing the symbol
error probability (Pe) of the PU. The proposed method is a
modulation approach in a single (complex-valued) dimension
rather than a high dimensional coding scheme. Although this
one-dimensional method is not capacity achieving, we show it still
has a remarkable performance with low amount of complexity.
An implementation algorithm for our modulation method is also
presented and the performance of this method is evaluated by
experimental results.

In this paper we examine the effect of relay (R) placement on the energy efficiency of a wireless sensor network (WSN) operating over a η-μ fading channel. We consider η-μ statistics for modeling the small scale fading affected wireless channel between the sensor nodes as the η-μ model is quite general in nature and it encompasses other popular fading models such as Rayleigh, Nakagami etc. In order to address the demand for high data rate WSN applications, spectrally efficient M-ary quadrature amplitude modulation (MQAM) is adopted. Transmission between a pair of sensor nodes is benefitted from a third node, placed in a collinear manner (i.e. on the same straight line, joining source and destination) between source (S) and destination (D), and acting as a relay (R). The relay operates in a selective decode and forward (DF) mode. It has been seen that it is more beneficial to place the R closer to S than D. We have also investigated the effective relay placement region and how different design parameters such as constellation size (M), path loss exponent (n) and fading parameters (η and μ) affect the placement region.

- by Nilanjan Biswas
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- Wireless relay (Engineering), Energy efficiency, Energy Efficiency

Energy harvesting (EH) cognitive relays are an exciting solution to the problem of inefficient use of spectrum while achieving green communications and spatial diversity. In a spectrum sharing scenario, we investigate the performance of a cognitive relay network, where a secondary source communicates with its destination over Nakagami-$m$ channels via decode-and-forward EH relays while maintaining the outage probability of the primary user below a predefined threshold. Specifically, we derive a closed-form expression for the secondary outage probability and show that it is a function of the probability of an EH relay having sufficient energy for relaying, which in turn, depends on the energy harvesting and consumption rates of the EH relay and the primary outage probability threshold. We also show that relaxing the primary outage constraint may not always benefit the cognitive EH relay network due to the limitations imposed on the relay's transmit power by the energy constraint.

We propose an efficient combination of distributed
switch and stay and selection relay that offers the best performance
at high SNRs compared to conventional selection relay
schemes and to incremental relaying schemes in conjunction with
selection relay. Our results, in terms of bit error probability,
confirm the benefit of the proposed scheme at high SNR regime.
We also show that the high-SNR performance of the proposed
scheme with more than two relays is dominated by the decodeand-
forward relaying link.

We propose an efficient combination of distributed switch and stay and selection relay that offers the best performance at high SNRs compared to conventional selection relay schemes and to incremental relaying schemes in conjunction with selection relay. Our results, in terms of bit error probability, confirm the benefit of the proposed scheme at high SNR regime. We also show that the high-SNR performance of the proposed scheme with more than two relays is dominated by the decode- and- forward relaying link.

This paper presents a MIMO two-way relaying
scheme where the transceiver filter at the Relay Station (RS)
processes the data using Recursive Least Square (RLS)
technique based on Inverse QR (IQR) algorithm. The relaying
technique used is Amplify and Forward scheme (AF). The
channel is assumed to be frequency selective and the Channel
State Information (CSI) is available only at the RS. So the
transmit and receive processing are both done at the RS.
Orthogonal Frequency Division Multiplexing (OFDM) is used
so as to combat the Inter-Symbol Interference (ISI) occurring
due to the frequency selectivity of the channel. The
performance of the IQR-RLS algorithm is verified by
comparing its Mean-Square error performance (MSE) with
that of a transceiver filter based on Normalized Least Mean
Square (NLMS) algorithm.

- by Vijaykumar Chakka
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- Wireless relay (Engineering), MIMO two way relay

- by Milad Fozooni
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- Millimeter Waves, MIMO Systems, Wireless relay (Engineering), Correlation

We propose an efficient combination of distributed switch and stay and selection relay that offers the best performance at high SNRs compared to conventional selection relay schemes and to incremental relaying schemes in conjunction with selection relay. Our results, in terms of bit error probability, confirm the benefit of the proposed scheme at high SNR regime. We also show that the high-SNR performance of the proposed scheme with more than two relays is dominated by the decode-and-forward relaying link.