Base station far-end radio-frequency apparatus and clock restoring apparatus

Abstract

The remote radio frequency unit of base station includes parts: serial-parallel conversion unit in use for sending parallel signals converted from serial signals to data processing unit as well as sending accompanied clock signal to data processing unit and clock recovery unit; clock recovery unit composed of hardware phase locked loop and software phase locked loop receives accompanied clock signal, and clock signal output from hardware phase locked loop is sent to the serial-parallel conversion unit and the data processing unit; clock signal output from software phase locked loop is sent to radio frequency unit; receiving accompanied clock signal and clock signal from the clock recovery unit, the data processing unit converts data from the serial-parallel conversion unit to synchronization from asynchronism, and outputs the converted data. Features are: providing local clock of possessing lower noise and stable time delay so as to meet requirement of communication protocol.

Description

technical field [0001] The invention relates to a base station remote radio frequency device and a clock recovery device in a mobile communication network. Background technique [0002] In the third generation mobile communication system, there is a system structure in which the baseband part and the radio frequency part of the base station are structurally and even geographically separated. In this structure, the radio frequency part of the base station is called a radio equipment (RE, Radio Equipment); the radio frequency control part and the baseband part of the base station are collectively called a radio equipment controller (REC, Radio Equipment Controller). One REC can carry one or more REs to form a distributed base station. REs and RECs can be placed together, or the REs can be placed far away through optical fibers or cables. Because in the distributed base station, the radio frequency device RE of the base station can be placed far away according to the actual ne...

AI Technical Summary

Problems solved by technology

[0006] The defect of hardware phase-locked loop to realize clock recovery is that in the hardware phase-locked loop, the filtering bandwidth of the loop filter cannot be made very narrow, although the filtering bandwidth can filter out most of the noise, but for the The near-end phase noise generated (that is, the noise whose frequency deviation is smaller than the loop bandwidth) cannot be effectively filtered by the loop filter, and the near-end phase noise of the PLL output clock will be mainly generated by the input PLL The phase noise performance of the accompanying clock (that is, the output clock of the previous RE) is determined; in the link of clock transmission, the serial / parallel transceiver (SERDES Serializer or Deserializer), the optical sending unit or the optical receiving unit will generate Noise, which leads to the deterioration of the phase noise performance of the associated clock input to the phase-locked loop (that is, the output clock of the upper stage RE), which in turn deteriorates the near-end phase noise of the phase-locked loop output clock

[0008] The defect of software phase-locked loop to achieve clock recovery is that the closed-loop control period of software phase-locked loop is longer (every 30s), so the frequency adjustment time is relatively long (software phase-locked loop can be regarded as a kind of "frequency-locked "algorithm), so that there is a frequency difference between the input and output clocks of the RE clock recovery unit (that is, between the local clock and the output clock of the upper-level RE)

When the output clock of the clock recovery unit is input to the data processing unit (Data Process), the frequency difference will cause high-speed data transmission to generate bit errors in the data processing unit; The time delay between the clock and the upper-level RE output clock is uncertain, so when the base station is configured for transmit diversity, this method is difficult to meet the delay requirements of transmit diversity

[0009] From the above analysis, it can be seen that the defect of the existing clock recovery device is that the output clock signal has unstable near-end phase noise, or there is an unstable time delay between the output clock and the input clock

Further, when the existing clock recovery device is applied to the remote radio frequency device of the base station, the local clock signal cannot meet the requirements of the remote radio device for low noise and stable delay of the local clock signal

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