Light emitting diodes - LEDs are modernizing the indoor illumination and replacing current incandescent and fluorescent lamps rapidly. LEDs have multiple advantages such as extremely high energy efficient, longer lifespan, and lower heat generation. Due to the ability to switch to different light intensity at a very fast rate, LED has given rise to a unique communication technology (visible light communication - VLC) used for high speed data transmission. By studying various kinds of commonly used VLC channel analysis: diffuse and line of sight channels, we presented a simply improved indoor and intra-vehicle visible light communication transmission model. Employing optical wireless communications within the vehicle, not only enhance user mobility, but also alleviate radio frequency interference, and increase efficiency by lowering the complexity of copper cabling. Moreover, a solution to eliminate ambient noise caused by environmental conditions is examined by using optical differential receiver. The simulation results show the improved received power distribution and signal to noise ratio - SNR.
Laser based radio communication system, i.e. OptoRadio, using Orthogonal M-ary PSK Modulation scheme is presented in this paper. In this scheme, when a block of data needs to be transmitted, the corresponding block of biorthogonal code is transmitted by means of multi-phase shift keying. At the receiver, two photo diodes are cross coupled. The effect is that the net output power due to ambient light is close to zero. The laser signal is then transmitted only into one of the receivers. With all other signals being cancelled out, the laser signal is an overwhelmingly dominant signal. The detailed design, bit error correction capabilities, and bandwidth efficiency are presented to illustrate the concept.
Free space laser communications provides wide bandwidth and high security capabilities to cellular backhaul network in order to successfully accomplish data communication between cell sites and NOC (Network Operation Center). For this application, an optical receiver is a critical component and needs to be designed to operate in sunlight and other ambient noise environments while providing reliable data transmission. In this paper, a method of Free Space Laser Communication along with a differential optical receiver is presented for the backhaul solution of 5G networks that provides high capacity, reliability, less deployment cost, and long distance reach. At the receiver, two photo diodes are cross coupled. The effect is that the net output power is close to zero. The laser signal is then transmitted only into one of the receivers. With all other signals being cancelled out, the laser signal is an overwhelmingly dominant signal. In the proposed configuration, two signals generating photo-receptors are arranged such that when they are opposed to one another, the effect is a cancellation, if and only if the both photo-receptors receive the same amount of input.
Orthogonal on–off keying (O 3 K ) is a coded modulation technique, where the input digital signal is mapped into a block of orthogonal codes. The encoded data, which is in orthogonal space, modulates the laser beam by means of O 3 K . At the receiver, two photocells are cross coupled to compensate for the sunlight and other atmospheric noise. Since the laser beam is highly directional and can only be acquired by one photocell, the input laser signal can then be received with little noise, and signal processing is made easier. These techniques are especially beneficial in high bandwidth, long distance secure laser communication applications, such as for use in unmanned aerial vehicles.
Orthogonal On-Off Keying is a coded modulation technique, where the input digital signal is mapped into a block of
orthogonal codes. The encoded data, which is in orthogonal space, modulates the laser beam by means of On-Off
Keying. At the receiver, two photo cells are Cross Coupled to compensate the sunlight and other atmospheric noise.
Since the laser beam is highly directional and can only be acquired by one photo cell, the input laser signal can then be
received with little noise, and signal processing is made easier. These techniques are especially beneficial in high
bandwidth, long distance secure laser communication applications, such as for use in Unmanned Aerial Vehicles.
KEYWORDS: Modulation, Error control coding, Signal processing, Transceivers, Binary data, Phase shift keying, Modulators, Composites, Systems engineering, Data transmission
In this paper we present a method of bandwidth efficient coded modulation suitable for spread spectrum radio with AJ- LPI capabilities. In the proposed scheme, we first examine the error control properties of orthogonal codes and show their potential uses in FECC. The aspect of this paper that motivates us is that an orthogonal code has an equal number of 1's and 0's. This is to say that an n-bit orthogonal code has n/2 1's and n/2 o's; i.e., there are n/2 positions where 1's and 0's differ. Therefore the distance between two orthogonal codes is also n/2. Exploitation of this distance property of orthogonal codes is the basis of our development in this paper. We then offer a simple and cost-effective solution to coded modulation without bandwidth expansion. We intend to show that parallel signal processing in conjunction with N-ary orthogonal signaling and M-ary modulation techniques offer a cost-effective solution to bandwidth efficient coded modulation.
In this paper we examine the vulnerability of ad hoc wireless networks due to intentional jamming and propose techniques to enhance network survivability. In the proposed scheme, we first examined the vulnerability of ad hoc wireless networks due to jamming and estimate the effort needed to protect the network. We then offer a hybrid solutions that combines source routing, Forward Error Control Coding, bandwidth efficient modulation, enhancement of hop count etc. We intend to show that, such a hybrid solution is an effective measure to protect ad hoc wireless networks from intentional jamming.
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