JinHyuk Song

A study on PLC synchronization based on PLC preamble correlation for DOCSIS 3.1 Downstream

In this paper, we propose a PLC synchronization method based on the correlation of PLC Preamble subcarrier in DOCSIS 3.1 Downstream system. The proposed method aims to find out the starting point of PLC Preamble OFDM symbol and to present the reference point for the allocation of pilot pattern used for channel estimation. We showed the performance of the proposed method through the maximum value detection of PLC preamble correlation.

Performance evaluation of lower layer system in cloud transmission for terrestrial DTV broadcasting

In this paper, we present the performance evaluation of lower layer system in Cloud transmission for terrestrial DTV broadcasting. As one of the service scenarios of Cloud transmission that is based on layered division multiplexing, the upper layer focuses on a low-data rate mobile service whereas the lower layer delivers a high-data rate fixed service mostly based on DVB-T2. This paper presents a detailed structure of Cloud transmission that consists of DVB-T2 as a lower layer system. The performance evaluation of the lower layer system is shown when errors are given to the upper layer and signal cancellation technique is performed for decoding the lower layer.

A study on common phase rotation compensation for coaxial transmission systems in the HFC network

We present a study result for common phase rotation compensation based on DSP and FPGA for coaxial transmission system in the HFC network. Recently, most of internet networks have HFC configuration. For 10Gbps speed in the HFC network, coaxial networks should support 10Gbps. For this, DVB-C2, DOCSIS 3.1, EPoC are developed. Especially, DVB-C2 attracts attentions for 8K-UHDTV services. Considering DVB-C2 in 10Gbps transmission, the common phase rotation should be compensated efficiently. The presented study result is focused on the computation and the processing of common phase rotation.

Study on an efficient fractional frequency offset estimation for OFDM systems with roll-off period

In this paper, we propose an efficient FFO(fractional frequency offset) estimation method for OFDM systems with RP(Roll-off period). RP is used to transmit more subcarriers in a limited bandwidth. Because neighboring OFDM symbols overlap in RP region, RP makes noises in CP(cyclic prefix) and degrades FFO estimation when Beeks method is used. The proposed method estimates FFO based on the Beeks method by detecting and eliminating RP from CP. We showed the test results of RP detection and explained the proposed FFO estimation.

Performance measurement of high-efficient OFDM based transmission system in commercial HFC network

This paper describes the results of a field test of an OFDM-based transmission system that uses digital video broadcasting for a cable system and is implemented using field programmable gate arrays (FPGAs). For the field test, a 4096QAM, 4096 Fast Fourier Transform (FFT), 9/10 code rate of a low-density parity check (LDPC), and 6-MHz channel bandwidth were selected. To evaluate the practical performance of the implemented transmission system, a commercial MPEG Analyzer is used for the performance evaluation.

Study on the influences of fractional frequency offset on PLC synchronization in DOCSIS 3.1

In this paper, we present the simulation results of FFO(fractional frequency offset) influences on PLC preamble correlation based PLC synchronization in DOCSIS 3.1 Downstream. FFO makes inter-carrier interferences and breaks orthogonality in OFDM based transmission system. It degrades the performance of OFDM by reducing SNR(signal to noise ratio). The performance of PLC synchronization is influenced by the reduced SNR caused by FFO. We analyzed the influences of FFO on PLC synchronization by applying various FFO values. We showed the PLC synchronization performances to various FFO values and discussed the results considering requirements of FFO compensation performance in OFDM signal reception.

Implementation and performance analysis of QAM modulator applicable to the HFC network

In this paper, we present an analysis of implemented QAM modulator in HFC network. It may be through the 256 QAM modulation using a single carrier to transmit data up to 38.8 Mbps. 64/256-QaM modulator based on ITU-T J.83 Annex B is implemented as a board which includes field programmable gate arrays (FPGAs). Implemented Modulator consists of RS-TCM encoder, a QAM modulator and Digital to analog converter (DAC). We analyze the received MPEG-2 TS stream and measured Program Clock Reference (PCR) jitter. TS stream is normally being received, PCR was confirmed to operate reliably within approximately -50 to +300 ns.

Energy efficiency of a wireless communication transmitter with intensity modulation

This paper describes a high speed optical wireless communication link that uses white-light-emitting diodes. We investigate the driving architecture about the energy efficiency of LED lightings and the spectral efficiency of communications.