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 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
- •
- Wireless relay (Engineering), MIMO two way relay

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.

IEEE 802.15.4 refers to a standard meant for short range wireless sensor networks (WSNs). Recently, the standard has gained huge popularity due to its simplicity, scalability, and low power consumption. In this paper, we investigate the energy efficiency of relay assisted dual hop communication between two 802.15.4 compliant wireless nodes. Novel energy consumption models for both amplify-and-forward (AF) and decode-andforward (DF) selective relaying protocols have been formulated and energy efficiency of these two protocols have been assessed by comparing the respective energy requirement per successful bit transmission. Small scale fading introduces outage during transmission over 802.15.4 links. The results show that although under moderate to high channel outage probability, DF relaying offers better energy efficiency than AF relays, when the outage is low, their performances become identical. Next, variation of energy consumption with data payload size is elaborated for both DF and AF relays. It was found that, under moderate outage, there exists an optimum value for the payload size where energy saving is maximum. For similar channel conditions, the optimum payload size is more for DF relays. When the outage value is very high energy consumption increases exponentially with payload size. The trend reverses when the outage is low.

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
- •
- 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.

In the next generation mobile network, the demand for
high data rate transmission will require an increase in the transmission
power if the current mobile cellular network architecture is used. Multihop
networks are considered to be a key solution to this problem. However,
a new resource allocation algorithm is also required for the new network
architecture. In this paper, we propose a resource allocation scheme for
a parallel relay 2-hop OFDMA virtual cellular network (VCN) which can
be applied in a multiuser environment. We evaluate, by computer simu-
lation, the ergodic channel capacity of the VCN using the proposed algo-
rithm, and compare the results with those of the conventional single hop
network (SHN). In addition, we analyze the effect of the location of the
relay wireless ports on the ergodic channel capacity of the VCN. We also
study the degree of fairness of the VCN, using the proposed scheme, com-
pared with that of the SHN. For low transmission power, the simulation
results show: a) the VCN can provide a better ergodic channel capacity and
a better degree of fairness than the SHN, b) the distance ratio for which
the ergodic channel capacity of the VCN is maximal can be found in the
interval 0.2∼0.3, c) the ergodic channel capacity of the VCN remains bet-
ter than that of the SHN as the number of users increases, and d) as the
distance between the relay WPs and the base station increases, the channel
capacity of VCN approaches that of the SHN.

- by Gerard Paraison and +1
- •
- Wireless relay (Engineering), Wireless Relay Networks, Multiuser Relay Networks

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

IEEE 802.15.4 has emerged as a popular standard for short range wireless sensor networks used in industrial, military, health, and environmental sectors. The limited lifetime of such networks is one of the critical design challenges. This paper examines the how relaying through intermediate sensor nodes can enhance the lifetime of an 802.15.4 network. In particular, novel energy consumption models for both AF and DF relays have been developed. Different relay gain scaling mechanisms and forwarding strategies under each of the relay categories were also considered and their energy efficiencies were compared. For every relaying protocol, it was found that there exists an optimum location where energy saving is maximum and this location is not necessarily different for different modes. In summary, it has been observed that the optimum location for AF relays is the equidistant point from source and destination. In contrast, the optimal location for DF relays is closer to source. The effect of different PHY level (outage probability, path loss) and MAC level parameters (frame length) on the energy efficiency are also studied.

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

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.

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.

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