Adaptive Forward Error Correction Coding Research Articles

Energy Efficiency Analysis in Adaptive FEC-Based Lightpath Elastic Optical Networks

In this paper, an energy efficiency (EE) analysis for elastic optical networks (EONs) considering the adaptive allocation of the transmitted power, spectrum bandwidth, modulation format and forward error correction (FEC) type has been proposed. The trade-off between the FEC coding types and the optical layer EE (OL-EE) was investigated considering the capacity of information transmission and power consumption. The power consumption model considers elements involved in the lightpath establishment, namely transmitter, receiver, bandwidth-variable optical crossconnect (BV-OXC), optical amplifiers and network control. Numerical examples have demonstrated EE increasing for the lightpaths when adaptive FEC coding is deployed; furthermore, the EE varies with the distance of the optical network nodes and hop count. In this sense, it is observed that the EE decreases with the increasing of FEC energy per bit consumption; however, an operation region is verified in which the overall EE network with FEC is superior to the system without FEC coding. After this point, the increases in the FEC energy per bit consumption will affect negatively the EE metric. For instance, with the proposed OL-EE model it is possible to determinate the maximum energy consumption allowed to the FEC codes without OL-EE system degradation.

Adaptive FEC coding and cooperative relayed wireless image transmission

High quality image transmission through smart devices requires high transmission rate, throughput and low Bit Error Rate (BER). At the same time, energy efficiency is always the top issue for the battery-based smart devices such as smart phone, tablets, etc. In this paper, an adaptive Forward Error Correction (FEC) coding and cooperative relayed image transmission system is proposed, through which both transmission quality and energy efficiency could be promised under complex mobile communication channel environment. There are four steps in the proposed scheme: (1) Discrete Wavelet Transform (DWT) and wavelet based Decomposition, (2) Pixel-Position (PP) information and Pixel-Value (PV) information split based unequal image resource allocation, (3) transmission through channel fading and AWGN communication environment, (4) multiple-relays and adaptive channel coding. Comparing to traditional methods, our proposed method is more practical to transmit high quality images through battery-limited smart phone platforms.

An adaptive FEC code control algorithm for mobile wireless sensor networks

For better performance over a noisy channel, mobile wireless networks transmit packets with forward error correction (FEC) code to recover corrupt bits without retransmission. The static determination of the FEC code size, however, degrades their performance since the evaluation of the underlying channel state is hardly accurate and even widely varied. Our measurements over a wireless sensor network, for example, show that the average bit error rate (BER) per second or per minute continuously changes from 0 up to 10−3. Under this environment, wireless networks waste their bandwidth since they can't deterministically select the appropriate size of FEC code matching to the fluctuating channel BER. This paper proposes an adaptive FEC technique called adaptive FEC code control (AFECCC), which dynamically tunes the amount of FEC code per packet based on the arrival of acknowledgement packets without any specific information such as signal to noise ratio (SNR) or BER from receivers. Our simulation experiments indicate that AFECCC performs better than any static FEC algorithm and some conventional dynamic hybrid FEC/ARQ algorithms when wireless channels are modeled with two-state Markov chain, chaotic map, and traces collected from real sensor networks. Finally, AFECCC implemented in sensor motes achieves better performance than any static FEC algorithm.

Design of multicode CDMA systems for 3-D stereoscopic video over wireless ATM networks

This paper investigates the application of multicode spread-spectrum code-division multiple-access (SS-CDMA) techniques to three-dimensional (3-D) stereoscopic video transmission over wireless asynchronous transfer mode (ATM) networks. Three-dimensional visual communications, made through the use of stereoscopic images, are able to achieve total display realism. Such services allow users to share the virtual reality (VR) world without any geographical restrictions. In order to create a 3-D system with two images (left and right) that should be transmitted over a bandlimited mobile channel simultaneously, a cost-effective motion picture experts group (MPEG)-based wavelet multiresolution coding with a joint motion and disparity compensation is developed to reduce a large amount of information contained in the images to meet the low-transmission rate limitation of mobile channels. However, the rapidly variable bit rate (VBR) characteristics of the MPEG-based 3-D videos seems a weakness to the transmission of such videos via a constant bit-rate (CBR) mobile channel. The ATM technique is especially well suited for VBR MPEG-based 3-D video because of its ability to allocate bandwidth on demand to these services. However, since the mobile radio has a limited channel capacity, the overall capacity of the traditional ATM-based SS-CDMA system may not be sufficient to accommodate the MPEG-based 3-D video services requested by the multiple mobile users simultaneously. To tackle this difficulty, a multicode CDMA technique is proposed to provide VBR MPEG-based 3-D video services by varying the number of spreading codes assigned to the 3-D video to meet its dynamic throughput requirement. Powerful forward error correction (FEC) codes are necessary to protect the video data so that it can be successfully transmitted at an acceptable signal power level. Two separate FEC code schemes are applied to the header and payload of an ATM cell containing 3-D video data, respectively. The ATM cell header is protected by a relatively powerful FEC code to ensure correct delivery and low cell loss rate (CLR). On the other hand, the ATM cell payload is encoded for varying degrees of error protection according to the priority of the payload data in 3-D videos. An adaptive FEC code combining scheme is proposed to provide the good protection for payload data with the maximization of its code rate to minimize the extra bandwidth for FEC overhead.