• Journal of applied mathematics & informatics
• /
• v.9 no.1
• /
• pp.231-238
• /
• 2002

In this paper, we study cyclic codes detecting a subclass of close-closed loop bursts viz. low-density close-closed loop bursts. A subclass of CT close-closed loop berets called CT low-density close-closed loop bursts is also studied.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.6B
• /
• pp.1068-1073
• /
• 2000

In this paper, we propose a serially concatenated turbo bode/turbo equalizer scheme for optical storage systems. Without modulation coding, a random data sequence is directly passed through the optical channel. In simulation, the channel includes jitter of 15% and AWGN. The densities of the channel are S=4.6 and S=7.0. The code rates of turbo code are 4/5, 8/9 and 16/17. All code rates, the bit error probability is less than 10-5 at 24dB when we and jitter of 15%.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.11
• /
• pp.1-8
• /
• 2008

In this paper, we analyze the symbol error rate (SER) performance of maximum likelihood (ML) joint detection in downlink multiple-input multiple-output (MIMO) multicarrier code division multiple access (MC-CDMA) systems by deriving a tight union bound on the symbol error rate (SER). The union bound for ML joint detection is utilized to demonstrate the performance of MIMO MC-CDMA systems quantitatively in multiuser and frequency selective Rayleigh fading environments. An analysis of the diversity order of the systems shows the effects of multiple users, spread subcarriers, and multiple antennas on the ML joint detection performance. Furthermore, the analysis shows that MIMO MC-CDMA systems without full loading can achieve more diversify than MIMO orthogonal frequency division multiplexing (OFDM) systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.8
• /
• pp.1437-1443
• /
• 2000

This paper considers a channel estimation technique in a wireless local area network (WLAN) system with complementary code keying (CCK) signaling over multipath fading channels. This scheme uses the maximum correlator output of RAKE receiver for the extraction of the channel parameters. The performance of the proposed detection technique is compared with that of a noncoherent detection technique, and a significant improvement of performance is observed in terms of the bit error probability.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.7B
• /
• pp.664-672
• /
• 2002

This paper analyzes a sequential estimator with flexible structure for rapid acquisition of the m-sequence signals. If the received PN chips stored in the estimator's internal registers as initial loading values include one error, this chip with error can be corrected through multiple local PN code generators to achieve high-speed acquisition performance. Hamming distance between regenerated local PN codes from the proposed system and received PN code is compared with given threshold to choose a possible correct path and to declare success of the code acquisition. Using signal flow graph, average acquisition time that depends on detection and false alarm probability is calculated. By modifying generally used matched filter structure for PN code acquisition, the proposed system provides flexible structure and rapid acquisition process.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.47 no.8
• /
• pp.32-41
• /
• 2010

We propose the use of multi-preambles using Gold codes and analyze its performance. The multi-preamble is a way of utilizing different codes for preambles according to operation modes or applications in a system. The receiver can be easily implemented using the maximum likelihood algorithm. The performance is robust against noise due to the good correlation characteristic of the Gold codes. We use 128-bit-long multi-preambles generated by 127 bit Gold codes in deriving the detection error probability and in verifying the validity through computer simulation. The results show that the theory and the experiment are in good agreement within the approximation error.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.9
• /
• pp.2035-2042
• /
• 1997

We consider the design of soft decision functions for each stage of multistage detection for coherent demodulation in an asynchronous code-division multiple-access(CDMA) system. In particular, the sigmoid function, which is shown to be optimal under the mean square error(MSE) criterion, andmultilevel quantizers that best approximate the sigmoid function are derived. At each stage of multistage detection, the parameters of these decision functions are adjusted depending on estimated input statistics. Computer simulation results demonstrate that multistage detectors employing these soft decision functions perform considerably better than those with hard decision.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.10B
• /
• pp.1246-1251
• /
• 2011

In this paper, BPSK-OFDM-based LED communication systems are applied to watermarking techniques, were studied on how to transfer the additional information data with at the same time as the transfer of LED communication data. For watermarking kasami code was used as spreading codes, and spread additional data is controlled by small signal level to be BPSK-OFDM does not affect the optical signal. BPSK-OFDM is added to an optical signal is transmitted. The performance of the spreading code as a kasami code is autocorrelation of the noise-free environment, under the noise environment was confirmed by autocorrelation. BPSK-OFDM-based LED communication system has been applied proposed technique throughout the simulation in analyzed to BER of BPSK-OFDM DER performance and watermark signal level according to signal size level of data. That was availability confirmed for watermarking data transmit techniques data as being analysis detection performance of watermarking information using LED communication according to the code.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.4
• /
• pp.39-46
• /
• 1994

In this paper, the idea of using a multiple symbol obervation interval to improve error probability performance is applied to differential detection of MTCM(multiple trellis code modulation) with ${\Pi}$/4 shift QPSK, 8DPSK and 16DPSK. We propose two types of sliding multiple symbol differential detection algorithm, type 1 and type 2. The two types of sliding detection scheme are examined and compared with conventional(symbol-by-symbol) detection and bolck detection with these modulation formats in an additive white Gaussian noise(AWGN) using the Monte Carlo simulation. We show that the amount of improvement over conventional and block detection depends on the number of phases and the number of additional symbol intervals added to the observation. Computer simulagtion results are presented for 2,4,8 states in AWGN channel.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.9
• /
• pp.13-18
• /
• 2015

The mutilevel holographic data storage offers considerable advantage for capacity, since it can store more than one bit per pixel. In this paper, we search the number of codewords for each code depending on three conditions: (1) the number of levels, (2) the number of pixels in a codeword, and (3) the minimum Euclidean distance of a code. Increasing the number of levels per pixel creates more capacity, while causing more errors, by reducing the noise margin. Increasing the number of pixels in a codeword can increase the code rate, which means more capacity, but increases the complexity of the encoder/decoder of the code. Increasing the minimum distance of a code reduces the detection error, while reducing the code rate of the code. In such a fashion, a system design will always have pros and cons, but our task is to find out an effective one under the given conditions for the system requirements. Therefore, the numbers we searched can provide some guidelines for effective code design.