Orthogonal frequency division multiplexing passive optical network system

Abstract

The invention provides an orthogonal frequency division multiplexing passive optical network system, which modulates an uplink data stream by using orthogonal frequency division multiplexing (OFDM) on the basis of not increasing hardware cost and media access control (MAC) complexity. The system adopts OFDM modulation for both uplink transmission and downlink transmission. In the OFDM modulation of uplink data, the positions and bandwidths of frequency bands allocated to each optical network unit and used for bearing valid uplink data in the whole converged OFDM frequency band are variable. Different frequency bands are allocated to uplink channels of different optical nodes, so that the frequency bands allocated to all the ONUs in the system and used for bearing the valid uplink data are positioned at different positions of the whole OFDM frequency spectrum, and are not overlapped with one another. An uplink transmission module can perform adaptive source configuration, dynamically allocate the number of sub-carriers according to the traffic of a user and regulate the bandwidths of the frequency bands used for bearing the valid uplink data.

Description

technical field [0001] The invention relates to communication technology, in particular to passive optical network communication. Background technique [0002] In the next-generation passive optical network (Passive Optical Networks, PON), common time division multiplexing PON (TDM-PON) and wavelength division multiplexing PON (WDM-PON) systems. TDM-PON access requires complex time control algorithms and framing techniques to support different applications; WDM-PON systems still lack the flexibility to dynamically allocate bandwidth between optical nodes, which is necessary for future optical access networks of. With the development of Orthogonal Frequency Division Multiplexing (OFDM) technology, its high spectrum utilization rate and large dispersion tolerance make it a more effective modulation method. However, the current PON only adopts the OFDM modulation method in the downlink transmission of data, and still uses the conventional OOK (On-off Key, on-off keying) and D...

AI Technical Summary

Problems solved by technology

The upstream data stream after OFDM modulation is optically modulated on the separated optical carrier through the optical modulator, so as to realize upstream transmission, which greatly increases the difficulty of system design, and WDM-PON still lacks the flexibility to dynamically allocate the bandwidth between optical nodes

In addition, the uplink receiving module uses different detectors for different wavelengths, that is, if there are N ONUs in the PON system, N uplink receivers are required to make the hardware cost of the OLT end high. OLT, the optical splitter at the OLT end demultiplexes the signal at the receiving end and divides it into N channels to each upstream receiver for detection reception and demodulation processing

Although the TDM access method does not need to use multiple uplink receivers, only one receiver needs to be installed in the uplink receiving module, but the TDM access method requires complex time control algorithms and framing techniques to support different applications. The ONU can only upload data in the assigned time slot, and the MAC protocol is also more complicated to control, and the upstream receiving module is difficult to implement, and it is impossible to realize the unified reception of data streams of multiple ONU units

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