Uplink transmission method for OFDMA-PON (Orthogonal Frequency Division Multiplexing Access-Passive Optical Network) system with low resource cost

Abstract

The invention provides an uplink transmission method for an OFDMA-PON (Orthogonal Frequency Division Multiplexing Access-Passive Optical Network) system with low resource cost. The uplink transmission method of the system is based on single sub-carrier modulated Gold sequences. ONUs (Optical Network Units) mounted in the PON (Passive Optical Network) system modulate different Gold sequences on a same distance measurement carrier, thereby distinguishing different ONUs. The good self-correlation characteristics of the Gold sequences are utilized at an OLT (Optical Line Terminal) end. Correlation operation is carried out on received uplink OFDM signals and natively stored ONU signals, thereby obtaining relative position information among the ONUs. The lengths of the Gold sequences are determined by the number of the ONUs. The CPs (Cyclic Prefixes) on the Gold sequences are set as zero. In order to simplify the calculation complexity of correlation operation, on the basis of the condition that the OFDMA-PON uplink is relatively stable, the OFDM signal word lengths participating in the correlation operation are optimized. According to the method, the logic complexity of the symbol synchronization of the OFDMA-PON uplink is greatly reduced.

Description

technical field [0001] The invention relates to an OFDMA (Orthogonal Frequency Division Multiple Access, Orthogonal Frequency Division Multiple Access)-PON (Passive Optical Network, Passive Optical Network) system uplink transmission method with low resource overhead. Background technique [0002] OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing technology) has gradually become the NG-PON2 (NextGeneration Passive Optical Network 2, next generation Research Trends of Generation Passive Optical Networks-2). The characteristics of OFDM modulation make it also suitable for passive optical network with multi-user access, and OFDMA-PON will be one of its best solutions. [0003] For the OFDMA uplink transmission system, due to the different distances between each ONU (Optical Network Unit, Optical Network Unit) and OLT (Optical Line Terminal, Optical Line Terminal) and the non-correlation in the time domain of OFDM signals sent by each ...

AI Technical Summary

Problems solved by technology

[0003] For the OFDMA uplink transmission system, due to the different distances between each ONU (Optical Network Unit, Optical Network Unit) and OLT (Optical Line Terminal, Optical Line Terminal) and the non-correlation in the time domain of OFDM signals sent by each ONU, it will cause each ONU OFDM signals arrive at the OLT at different times, which will cause OFDM multi-user inter-symbol interference during reception and demodulation

In the existing design system, Johannes von Hoyningen-Huened et al. use an independent FFT (Fast Fourier Transformation, Fast Fourier Transformation) operation for the data stream of each ONU at the OLT end to realize the upstream transmission of OFDMA-PON. However, this solution requires the use of parallel FIR (Finite Impulse Response, finite-length unit impulse response) digital filters and multiple FFTs, and cannot achieve flexible bandwidth scheduling, and as the number of ONUs increases, the overhead of its logic resources will also increase. Dramatic increase

However, Ali Razmtouz and others used the Zadoff-Chu sequence to solve the uplink ranging problem, and achieved frequency domain compression by extending the sequence in the time domain, and then moved it to the specified frequency band, but this solution needs to occupy multiple carriers , and a corresponding guard interval needs to be reserved. In addition, the data stream of the ranging carrier is added to the OFDM data stream in the form of a prefix, which will reduce the effective data transmission rate of the ONU

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