CN104378850A

CN104378850A - Distributed base station

Info

Publication number: CN104378850A
Application number: CN201310358991.6A
Authority: CN
Inventors: 冯绍鹏; 张瑞; 王绪振
Original assignee: Potevio Institute of Technology Co Ltd
Current assignee: Potevio Institute of Technology Co Ltd
Priority date: 2013-08-16
Filing date: 2013-08-16
Publication date: 2015-02-25

Abstract

The invention discloses a distributed base station which comprises a remote radio unit and a base-band processing unit. The distributed base station is characterized in that the base-band processing unit carries out bit-level processing in the downlink transmission direction, and the remote radio unit carries out symbol-level and following processing. By means of the distributed base station, the downlink bandwidth of the Ir port can be effectively reduced.

Description

A kind of distributed base station

Technical field

The application relates to mobile communication technology field, particularly relates to a kind of distributed base station.

Background technology

In mobile communication system, the distributed base station of baseband processing unit (BBU)+Remote Radio Unit (RRU) has obtained large-scale application, and this networking mode also will be applied to LTE system, TD-SCDMA system etc.By Optical Fiber Transmission base band I/Q signal between BBU and RRU, the interface between BBU and RRU is called Ir interface, and the bandwidth of Ir interface depends on the transmission rate of baseband signal.

In prior art, the conventional dividing mode of BBU and RRU as shown in Figure 1.Code block segmentation is done to bit stream in base station, rate-matched, chnnel coding, scrambling, and layer maps, symbol-modulated, precoding, resource mapping, does IFFT conversion, sends after middle radio frequency processing on individual transmitting antenna.Wherein, BBU completes bit-level, and symbol level is until the process of time domain data framing of multiple antennas.RRU completes Digital Up Convert, D/A conversion process of Denging.The data that Ir interface so between BBU-RRU transmits comprise multiple antenna, the time-domain signal of a subframe.The function of carrying out BBU and RRU in a conventional manner divides, BBU-RRU interface is by the time domain data under the multiple transmitting antenna base band sampling rate of transmission, downlink transmission data amount is huge, and consumes resources is too much, and single RRU transmitted data amount is directly proportional to RRU antenna number, bandwidth.

For LTE system, under 20MHz bandwidth, when base station side antenna configuration is 8 antenna multiple-input and multiple-output (MIMO), Ir interface bandwidth is calculated as follows:

Uplink traffic transmission data volume=30.72MHz(sampling rate) × 16 (sampling precision) × 2(I/Q two-way) × 8(antenna number)=7864.32Mbps.

Therefore, under 8 antenna LTEs configurations, generally need to adopt bandwidth to be the Optical Fiber Transmission Ir interface data of 10GHz bandwidth.

Under the trend that LTE is growing to high bandwidth, multiple antennas MIMO, many RRU multipoint cooperative application demand, single RRU supports that bandwidth increases, antenna number increases, BBU connects RRU and increases, the data volume that conventional RRU-BBU data file interface design will transmit also will increase thereupon, and this continuation to LTE development will be one and seriously hinder.

Summary of the invention

This application provides a kind of distributed base station, effectively can reduce the downlink bandwidth of Ir interface.

A kind of distributed base station that the embodiment of the present application provides, comprises Remote Radio Unit and baseband processing unit, and on downlink transmission direction, baseband processing unit carries out bit-level process, and Remote Radio Unit carries out symbol level and subsequent treatment.

Preferably, described baseband processing unit comprises transport block cyclic redundancy check CRC computing module, code block segmentation and CRC attachable module, channel coding module, Rate Matching block, code block cascade module and bit scramble module;

Described Remote Radio Unit comprises symbol-modulated module, layer mapping block, precoding module, resource mapping module, power regulation module, wave beam forming module, inverse fast Fourier transform module, adds cyclic prefix module, Digital Up Convert module and digital-to-analogue conversion D/A module.

Preferably, baseband processing unit by following parameter transmission to Remote Radio Unit:

User's required parameter that the information of the wave beam forming factor of user, the power adjusting factor of user, user, Physical HARQ Indicator Channel PHICH data content and upper row relax need.

Preferably, the information of described user comprises: multiple-input and multiple-output MIMO mode, pre-coding matrix PMI and code word number indicate.

As can be seen from the above technical solutions, by repartitioning the functional module of BBU and RRU, only bit-level process is placed on BBU and realizes, symbol level and subsequent treatment are placed on RRU and realize, and effectively can reduce the downlink bandwidth of Ir interface.

Accompanying drawing explanation

Fig. 1 is the functional block diagram of RRU and BBU in prior art;

The functional block diagram of RRU and BBU that Fig. 2 provides for the embodiment of the present application.

Embodiment

For making the know-why of technical scheme, feature and technique effect clearly, below in conjunction with specific embodiment, technical scheme is described in detail.

Ir interface data between RRU-BBU is directly proportional to descending number of transmit antennas.For BBU and the RRU function dividing mode of routine, RRU-BBU interface data is the time domain data of the base band sampling rate of multiple reception antenna.In order to reduce the transmission quantity of interface data, the design philosophy of the application is exactly the foundation as far as possible selecting the module interface had nothing to do with antenna to repartition as BBU and RRU function, to reach the object reducing RRU-BBU interface data bandwidth.

Based on above-mentioned consideration, in the distributed base station that the embodiment of the present application provides, only bit-level process is placed on BBU and realizes, symbol level and subsequent treatment are placed on RRU and realize.That is: after repartitioning, the mapping of symbol-modulated, layer, precoding, resource mapping, power adjustment, beam shaping, inverse fast Fourier transform (IFFT) and add Cyclic Prefix (CP) module, be divided into RRU by BBU and realize.The Module Division that then BBU and RRU is new as shown in Figure 2.Baseband processing unit comprises transmission block (TC) Cyclic Redundancy Check computing module, code block segmentation and CRC attachable module, channel coding module, Rate Matching block, code block cascade module and bit scramble module; Remote Radio Unit comprises symbol-modulated module, layer mapping block, precoding module, resource mapping module, power regulation module, wave beam forming module, inverse fast Fourier transform module, adds cyclic prefix module, Digital Up Convert (DUC) module and digital-to-analogue conversion (DA) module.

According to technical scheme, after repartitioning the function of BBU and RRU, BBU is the bit field data after bit scramble by the data that Ir interface transmits, instead of the I/Q data of symbol.BBU carries out mark process to each RE data, identifies these flag bits with the least possible bit.In this processing mode, the bit contents of often kind of channel storage has different meanings.The relevant parameter that the bitstream data amount of interface transmission and BBU pass to RRU is calculated as follows:

After repartitioning, the bitstream data of interface transmission, modulation system is for 64QAM, and data volume is

8(cw)*1200(RE)*14(symb)*6bit*1000=806.4Mbps；

Realize due to the functions such as modulation, layer mapping, precoding, power adjustment and wave beam forming are moved to RRU, BBU also needs to be transferred to the relevant parameter of below RRU, the process for follow-up RRU:

1) the wave beam forming factor of user:

Data volume is 100 (RB) * 8 (ant) * 24bit (IQ) * 1000=19.2Mbps;

2) power adjusting factor of user:

Data volume is 100 (RB) * 8 (ant) * 24bit (IQ) * 1000=19.2Mbps;

3) information of user, comprises the instruction of MIMO mode, pre-coding matrix PMI and code word number:

Data volume is 100 (RB) * 8 (ant) * 8bit*1000=6.4Mbps;

4) Physical HARQ Indicator Channel (PHICH) data content, what the mapping position of corresponding HARQ instance instruction (HI) stored is group number and the data-bias number of HI on this position, so HI needs an independent block space to carry out buffer memory actual data content, data depth is 25*12, data bit width is 22bit, wherein 25 is the PHICH group number of maximum possible, and 12 is the sequence number in each PHICH group:

Data volume is 25 (groupid) * 12 (seqid) * 22bit*1000=6.6Mbps.

5) user's required parameter of upper row relax needs:

Data volume is 32packet*256Byte*1000=8.2Mbps

To sum up, the downlink port transmitted data amount that the present invention proposes is:

806.4Mbps+19.2Mbps+19.2Mbps+6.4Mbps+6.6Mbps+8.2Mbps=866Mbps。Compared with the transmitted data amount of the 9830.4Mbps before repartitioning, interface bandwidth significantly reduces.

The foregoing is only the preferred embodiment of the application; not in order to limit the protection range of the application; within all spirit in technical scheme and principle, any amendment made, equivalent replacements, improvement etc., all should be included within scope that the application protects.

Claims

1. a distributed base station, comprises Remote Radio Unit and baseband processing unit, it is characterized in that, on downlink transmission direction, baseband processing unit carries out bit-level process, and Remote Radio Unit carries out symbol level and subsequent treatment.

2. distributed base station according to claim 1, it is characterized in that, described baseband processing unit comprises transport block cyclic redundancy check CRC computing module, code block segmentation and CRC attachable module, channel coding module, Rate Matching block, code block cascade module and bit scramble module;

3. distributed base station according to claim 2, is characterized in that, baseband processing unit by following parameter transmission to Remote Radio Unit:

4. distributed base station according to claim 3, is characterized in that, the information of described user comprises: multiple-input and multiple-output MIMO mode, pre-coding matrix PMI and code word number indicate.