Analysis of Simplified Frame Synchronization Scheme for Burst-Mode Multi-Carrier System

Analysis of Simplified Frame Synchronization Scheme for Burst-Mode MultiCarrier System

Abstract: Frame synchronization is one of the basic functions units in a burst-mode digital communication receiver. In a lot of burst communication systems, a preamble is placed at the start of a signal burst for synchronization and channel estimation.

Using a cross-correlation detector to calculate the correlation between the local preamble sequence and the received preamble sequence is a common synchronization method. Simplified cross-correlation-detector which quantizes each detected sample into 1 bit can dramatically reduce the consumption of the chip resource when implemented in hardware. In this letter, performance analysis for simplified cross-correlation-detector whose input is multi-carrier modulated signal is presented. The relationships between correlation length, decision threshold, and the probabilities of false alarm and missing detection are given. The correctness of the detector is validated through system simulations and numerical calculations.

Existing system:

Mode communication refers to discontinuous and a periodic data transmission, in which the receiver needs to detect the arrival of a data frame and synchronize with the start of the frame. Known data sequence called as preamble is placed in the start of data frames to facilitate burst detection and frame synchronization. The advantage of burst mode communication is that multiple communication nodes can share the same channel. A typical example is Wireless Local Area Network (WLAN). One of the fundamental functions of the burst based receiver is the burst detection which identifies the arrival of a burst. To facilitate acquisition, a known sequence (preamble) is prefixed at the beginning of each burst. Numerous literatures has contributed on burst detection method with performance analysis.

The most straightforward method is energy detection or non-coherent detector, where the average power of the received signal is calculated and compared with a threshold.

Proposed system: However, the cross-correlation detector is resource-consuming when implemented in hardware such as Field Programmable Gate Array (FPGA) or Applicationspecific integrated circuit (ASIC). Its simplified version named as simplified crosscorrelation (SCC) which only takes the sign bit (hard decision) both for local sequence and the received signal has been proposed in a number of works . It can reduce chip area dramatically when implemented in ASIC or FPGA. For the case of single carrier modulation binary antipodal signaling, SCC detectors acquisition performance was analyzed. In low signal to noise power ratio (SNR) region, its performance is inferior to the soft-correlation; in practical SNR region (SNR ď‚ł 0dB), its performance is even better than soft correlation. For the burst-mode multi-carrier system including the OFDM and discrete multi-tone (DMT) systems, the preamble is a superimposition of a large number of carriers, whose amplitude follows Gaussian distribution. To the best of our knowledge, the performance of SCC detector has not been explored yet.

Advantages: Numerous literatures has contributed on burst detection method with performance analysis. The most straightforward method is energy detection or non-coherent

detector, where the average power of the received signal is calculated and compared with a threshold.

In addition, the auto-correlation (AC) or differential coherent detector is frequently used in orthogonal frequency division multiplexing (OFDM) systems for burst acquisition. If the preamble is known by the receiver, the cross-correlation (CC) between the waveform.

Disadvantages: However, the cross-correlation detector is resource-consuming when implemented in hardware such as Field Programmable Gate Array (FPGA) or Applicationspecific integrated circuit (ASIC). Its simplified version named as simplified crosscorrelation (SCC) which only takes the sign bit (hard decision) both for local sequence and the received signal has been proposed in a number of works.

It can reduce chip area dramatically when implemented in ASIC or FPGA. For the case of single carrier modulation binary antipodal signaling, SCC detectors acquisition performance was analyzed. In low signal to noise power ratio (SNR) region, its performance is inferior to the soft-correlation.

Modules: Wireless local area network: Mode communication refers to discontinuous and a periodic data transmission, in which the receiver needs to detect the arrival of a data frame and synchronize with the start of the frame. Known data sequence called as preamble is placed in the start of data frames to facilitate burst detection and frame synchronization. The advantage of burst mode communication is that multiple communication nodes can share the same channel. A typical example is Wireless Local Area Network (WLAN). One of the fundamental function of the burst based receiver is the burst detection which identifies the arrival of a burst. To facilitate acquisition, a known sequence (preamble) is prefixed at the beginning of each burst. Numerous literatures has contributed on burst detection method with performance analysis.

The most straightforward method is energy detection or non-coherent detector, where the average power of the received signal is calculated and compared with a threshold.

Simplified cross – correlation: However, the cross-correlation detector is resource-consuming when implemented in hardware such as Field Programmable Gate Array (FPGA) or Applicationspecific integrated circuit (ASIC). Its simplified version named as simplified crosscorrelation (SCC) which only takes the sign bit (hard decision) both for local sequence and the received signal has been proposed in a number of works. It can reduce chip area dramatically when implemented in ASIC or FPGA. For the case of single carrier modulation binary antipodal signaling, SCC detectors acquisition performance was analyzed. In low signal to noise power ratio (SNR) region, its performance is inferior to the soft-correlation; in practical SNR region (SNR  0dB), its performance is even better than soft correlation. For the burst-mode multi-carrier system including the OFDM and discrete multi-tone (DMT) systems, the preamble is a superimposition of a large number of carriers, whose amplitude follows Gaussian distribution. To the best of our knowledge, the performance of SCC detector has not been explored yet.

Design engineer : One of the concerns for the system or algorithm design engineers is the comprehensive performance comparison between CC and SCC detectors. The advantage of SCC detector vs CC detector lies in reduced hardware resource consumption under the condition of PFA and PM is the same. However, it is trivial to find out the configuration that both detectors have exactly same performance (PFA vs PM) curves, so we find a case that SCC detector performs a little better than CC detector as shown in Fig. 5 and then compare the hardware resource consumptions by SCC and CC detectors in this case. In, when the SNR is 0dB, the performance curve of CC detector with N=64 and SCC detector with N=160 is quite close. Then, the hardware resource consumptions are compared based on this condition. We implemented the two detectors on Altera FPGA cyclone V 5CSEMA5F31C6, whose basic function unit is adaptive logic modules-ALM. For CC detector, both local.