The authors consider errorcorrection codes for HF channels, explaining the advantages of adaptive coding schemes. An incremental redundancy coding scheme based on product codes is introduced. The codes described are ...
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The authors consider errorcorrection codes for HF channels, explaining the advantages of adaptive coding schemes. An incremental redundancy coding scheme based on product codes is introduced. The codes described are tested by means of HF channel simulation.< >
The techniques used both for encoding and decoding the RS(15,11) code are discussed. It is found to be advantageous to use several representations of the code in the time domain as well as being able to use its spectr...
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The techniques used both for encoding and decoding the RS(15,11) code are discussed. It is found to be advantageous to use several representations of the code in the time domain as well as being able to use its spectral properties. The ability to move easily within these representations is very important. Various means of performing these translations, including the Fourier transform over a finite field, are described. Additionally the hardware consequences of using these algorithms are examined. Possible implementations using programmable devices and ASICs are presented.< >
In the search for good error control codes with known decoding algorithms, for the frequency hopping HF channel, the authors have studied how channel measurement information can improve the error-correcting capability...
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In the search for good error control codes with known decoding algorithms, for the frequency hopping HF channel, the authors have studied how channel measurement information can improve the error-correcting capability of the code. They show the performance of some well-known error-correcting codes when used on the HF channel together with channel measurement information. A frequency hopping system working at HF has been built and tested. The system is built as an experimental system to investigate the various problems one has to deal with when using spread-spectrum coding. The intention is to demonstrate the efficiency with this kind of system compared to other systems in a hostile jamming environment. Based on data recorded from the HF system they have implemented two types of soft decoding algorithms in software and simulated their performances. The two decoding algorithms are the Blokh-Zyablov algorithm and the Chase algorithm.< >
In order to combine the copyright protection with the content authentication commendably in the digital watermark, this paper proposes an improved error correction coding -based multipurpose method where the authentic...
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In order to combine the copyright protection with the content authentication commendably in the digital watermark, this paper proposes an improved error correction coding -based multipurpose method where the authentication watermark and the robust watermark are embedded in the different coefficients of DCT transform domain respectively. In addition, to strengthen the security, the method still utilizes the error correction coding. Through a series of experiment, the invisibility of the method can be proved both from the PSNR value (PSNR=51.2dB) and the histogram equalization. The similarity between the original watermark and extracted watermark is almost above 95%. The proposed method is effective in image authentication and it's robust against some image processing operations, such as low-pass filtering, Gaussian noise, JPEG lossy compression, cropping and histogram equalization.
ICI has developed a unique and novel method of certifying a Terabyte optical tape. The tape quality is guaranteed as a statistical upper limit on the probability of uncorrectable errors. This is called the corrected b...
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ICI has developed a unique and novel method of certifying a Terabyte optical tape. The tape quality is guaranteed as a statistical upper limit on the probability of uncorrectable errors. This is called the corrected byte error rate (CBER). The author developed this probabilistic method because of two reasons why error rate cannot be measured directly. Firstly, written data is indelible, so one cannot employ write/read tests such as used for magnetic tape. Secondly, the anticipated error rates need impractically large samples to measure accurately. For example, a rate of 1E-12 implies only one error per tape. Nevertheless, customers expect performance predictions which are supported by practical test results. The paper describes the mathematical basis, measurement apparatus and applicability of the method.< >
The resurgent use of HF, the increase in VHF/UHF usage and in particular the employment of data transmission has meant that the newer enabling technologies such as digital signal processing (DSP) have found a fertile ...
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The resurgent use of HF, the increase in VHF/UHF usage and in particular the employment of data transmission has meant that the newer enabling technologies such as digital signal processing (DSP) have found a fertile ground in these mature electronic technologies. The main reason is the ability of DSP to overcome the problems that have dogged earlier users. For example, adaptive modem techniques have permitted us to negate the vagaries of the single ionospheric path. DSP techniques can also improve systems by means of real time channel evaluation (RTCE), which allows a rapid choice to be made of the best out of a number of assigned channels. Although both these approaches work exceedingly well in the single path situation, they are less effective in the case of multiple-user networks as each link is unique in terms of transmission conditions and each node is susceptible to a separate set of interference conditions! The authors discuss some 'operational realities', then lead on to a highly effective code, which (a) offers not only a greater data throughput than conventional ASCII codes (and thus makes it applicable to the whole of the radio spectrum as well as line communications) but (b) also offers a bit errorcorrection technique, having the capability of tolerating high levels of interference-a daunting problem at HF-and it is the latter that provides the special solutions for networked systems, which neither the adaptive nor the RTCE methods appear able to tackle effectively. The proposed solution arises from a code based on the Fibonacci series, as opposed to codes based on standard binary progressions. This structure offers an 'intrinsic RTCE method', thus providing independence to the receiving systems.
The technique of embedded coding has been shown to be advantageous compared to conventional ARQ systems which use a single basic code rate. This technique provides a highly reliable method of errorcorrection while ma...
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The technique of embedded coding has been shown to be advantageous compared to conventional ARQ systems which use a single basic code rate. This technique provides a highly reliable method of errorcorrection while maintaining a relatively high average code rate and is therefore suitable for use on time-varying channels such as the HF (3 MHz-30 MHz) skywave channel. The use of Reed-Solomon codes in an embedded scheme is analysed and results are presented verifying the improvement which can be obtained compared to previously reported embedded coding schemes.< >
In this paper the error-control coding techniques used in GSM/EDGE Radio Access Network (GERAN) are considered. Application of coding schemes is restricted by the corresponding traffic channels (TCH). Knowing the gene...
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In this paper the error-control coding techniques used in GSM/EDGE Radio Access Network (GERAN) are considered. Application of coding schemes is restricted by the corresponding traffic channels (TCH). Knowing the general scheme is necessary for modeling the work of the complete error-control system. This knowledge can be useful for the implementation of educational software used for the investigation of the properties of different codecs and their characteristics in radio channels using various radio channel models.
The objective of the proposed paper is to investigate an adaptive concatenated codes, which can provide a more efficient error protection in the channels with different types of errors. The block diagram of the propos...
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The objective of the proposed paper is to investigate an adaptive concatenated codes, which can provide a more efficient error protection in the channels with different types of errors. The block diagram of the proposed technique is presented. These codes provide different random error protection capability, which is related to guard space between a burst of errors. To achieve an additional protection for bursty channels, we have implemented a majority logic encoder and decoder.< >
Hybrid ARQ/FEC protocols have been proposed to provide high data link integrities whilst keeping at the same time a high mean throughput rate. Nevertheless, hybrid ARQ strategies offer a lot of choices and none of the...
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Hybrid ARQ/FEC protocols have been proposed to provide high data link integrities whilst keeping at the same time a high mean throughput rate. Nevertheless, hybrid ARQ strategies offer a lot of choices and none of them can be considered the optimum in any case. Three alternative protocol strategies using BCH codes are evaluated and the HF channel models used for the tests are discussed.< >
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