Uplink synchronisation method, base station, terminal and communication system

Abstract

A method for uplink synchronization, a base station, a terminal and a communication system are disclosed by the present invention. Wherein, the method for uplink synchronization comprises the following steps: receiving a MAC Protocol Data Unit (MAC PDU), which includes a Timing Advance (TA) value, transmitted by the base station; according to the TA value identification information in said MAC PDU, identifying whether said TA value is the TA value of the sounding reference signal; if said TA value is the TA value of the sounding reference signal, performing the time offset adjustment according to the TA value. The embodiments of the present invention can identify whether a TA value is the TA value of the sounding reference signal or the TA value of the Random Access Channel (RACH) detection according to the TA value identification information in the MAC PDU. Only when a TA value in the MAC PDU is the TA value of the sounding reference signal, the corresponding time offset adjustment is performed accordingly, thus ensuring the uplink synchronization performance of the OFDM system.

Description

technical field [0001] The invention relates to communication technology, especially an uplink synchronization method, a base station, a terminal and a communication system. Background technique [0002] Orthogonal Frequency Division Multiplexing (hereinafter referred to as: OFDM) is the core technology of the fourth generation (the 4th Generation, hereinafter referred to as: 4G) mobile communication. Converts to a flat channel, thereby reducing the effects of multipath fading while improving spectrum utilization. However, the OFDM system is extremely sensitive to synchronization errors and has high requirements for time synchronization. In terms of frequency synchronization, frequency offset (abbreviation: frequency offset) will introduce internal channel interference (Internal Channel Interference, hereinafter referred to as: ICI), that is, inter-carrier interference, which deteriorates the signal-to-noise ratio of each subcarrier, thereby deteriorating the overall Trans...

AI Technical Summary

Problems solved by technology

[0007] Because the baseband DSP not only reports the TA value detected based on the sounding reference to the MAC module through the above message, but also reports the TA value detected based on the preamble (Preamble) sent by the RACH to the MAC module through the message, that is, the baseband DSP Through the same message, two TA values ​​detected based on the sounding reference signal and the preamble are reported to the MAC module. The MAC module cannot distinguish whether the received TA value is based on the TA value detected by the sounding reference signal or based on the preamble. The detected TA value, so that no distinction is made when sending the TA value to the UE through the MAC PDU

When the UE receives the TA value delivered by the MAC module, it cannot distinguish its type. Since the TA value detected based on the preamble has a relatively high probability of being wrong, the performance of time offset adjustment may be reduced, that is to say, it will cause Degradation of Uplink Synchronization Performance in OFDM System

In addition, due to the influence of noise, there may be a false alarm when the UE detects the TA value. In this case, it will further affect the performance of the time offset adjustment.

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