WO2013123787A1

WO2013123787A1 - Lte-ir interface data compression method and device thereof

Info

Publication number: WO2013123787A1
Application number: PCT/CN2012/085130
Authority: WO
Inventors: 陈聃青; 高远; 朱莉森
Original assignee: 大唐移动通信设备有限公司
Priority date: 2012-02-22
Filing date: 2012-11-23
Publication date: 2013-08-29
Also published as: CN102612079B; CN102612079A

Abstract

An LTE-IR interface data compression method and device for use in a distributed base station provided with a lookup table, the creation process of said lookup table comprising: dividing the value range of the absolute values of the to-be-compressed data into a number 2N of value intervals, wherein N is the bit width of the compressed data after a sign bit is removed; selecting a value in each value interval as the identification value of the value interval, and saving the selected values into the lookup table in an ascending or descending order, the address of each identification value in the lookup table being the compression result value of the to-be-compressed data in the corresponding value interval; during data compression, using a binary search algorithm to search in the lookup table for the identification value of the value interval to which the absolute value of the to-be-compressed data belongs; and according to the address of the found identification value of the value interval in the lookup table, determining the compression result value of the to-be-compressed data. The present application reduces the difficulty of technical implementation and reduces resource occupation while satisfying existing requirements for data compression.

Description

LTE-IR interface data compression method and device thereof The present application claims to be submitted to the Chinese Patent Office on February 22, 2012, the application number is 201210042937.6, and the invention name is "an LTE-IR interface data compression method and device thereof" Priority of Chinese Patent Application, the entire contents of which is incorporated herein by reference.

Technical field

The present application relates to the field of wireless communications, and in particular, to an LTE-IR interface data compression method and apparatus therefor. Background technique

With the development of mobile communication technology, high-speed and large-capacity data transmission is an inevitable trend. The increase in the amount of data also places higher demands on the optical fiber data transmission speed of the base station. When a single fiber cannot meet the transmission rate, high-speed data transmission can only be achieved by increasing the fiber rate or increasing the number of fibers. Both of these methods increase equipment costs.

The LTE (Long Term Evolution) base station is a distributed base station device, which is composed of a Base Band Unit (BBU) and a Remote RF Unit (RRU). The RRU and the BBU are connected by optical fibers. Since the maximum IQ (orthogonal two baseband signals) data sampling width of the system is 16 bits, the optical fiber transmission needs to encode the data by 8/10. Therefore, for a device with 8 antennas and 20M bandwidth, the maximum line rate of the optical port is:

30.72M*32bit*8 antenna * ( 10/8 ) =9.8304Gbps

At present, the data transmission of the base station optical port only supports 6.144 Gbps. To complete the data transmission of 20M8A (A for the antenna), it is necessary to use an optical port supporting 10G rate, or two optical ports of 6.144G rate and two optical fibers for data transmission. As the number of antennas or system bandwidth increases, the cost of fiber for base station equipment will increase further.

The data transmission between the RRU and the BBU follows the LTE-IR interface protocol standard. The LTE-IR interface protocol specifies that the basic frame length of data transmission is 1 Tc=l/3.84 MHz. A basic frame contains 16 words, word length T is determined by the line bit rate. In a basic frame, the bitO bit of the I/Q data is discarded, and only 15 bits high are transmitted, leaving a word for control word transmission. 1 is a frame structure diagram of a word length T. Where W is the word, Y is the number of bytes, and B is the number of bits. When the line rate is 9.8304 Gbps, T is equal to 128.

The specific implementation of the IR interface data compression algorithm can be divided into four steps:

(1) AGC (Automatic Gain Control) processing: Estimate the amplitude of the digital signal transmitted by the IR interface in units of symbol (symbol) and adjust it to the expected target value for later compression. deal with. Usually implemented by a shift operation.

(2) Compression: The compression of the baseband data from 16bit to 7bit is the core part of the IR interface data transmission compression process.

(3) Decompression: It is the inverse process of the compression module, and the algorithm used depends on the compression algorithm. Usually use the look-up table method.

(4) Solution AGC processing: The reverse process of AGC processing.

Since the IR interface function of the RRU and the BBU is implemented by an FPGA (Programmable Gate Array), data compression is also performed on the FPGA. Figure 2 is a schematic diagram of the structure of the IR interface data compression.

The A-law compression algorithm is a non-uniform hook speech compression algorithm mainly used in public telephone networks. The A-law characteristic is defined as:

Alxl

Sgn(x)—— LL^, 0 < |x| < l/A

^{,; L + ln (A)} 1 1 1

Y— , , l + ln ( I) , , , [1]

s ^{gn x} - lΓ +- lΓn7(AΓ) '< x≤l In equation (1), x is the normalized input speech signal, sgn(x) is the sign bit of X, and y is the normalized after companding The output signal, A is the value of the compression parameter.

The optimized A-law compression algorithm has three implementations on the FPGA:

(1) Lookup table method: Put the A-law compression result value in the ROM (Read-Only Memory) table, and the read address of the compression result value is the corresponding pre-compression data, and the input signal is used as the ROM. The read address lookup table can get the compressed result value.

(2) Calculation method: The A-law calculation formula is realized by constructing a logic circuit.

(3) Linear Approximation: The A-law curve is approximated by a number of fold lines. The typical application is the 13-fold line method of A=87.6. The 13-fold line method can compress 16-bit wide input data to 8-bit width, and the performance loss is small, but for 7-bit compression, the performance loss is unacceptable. Considering that the statistical characteristics of the LTE signal and the characteristics of the speech signal are different, the IR interface bit compression algorithm optimizes the parameter A through different simulation experiments of the scene to achieve 7-bit compression.

The main disadvantages of the existing three A-law algorithm implementations are:

(1) Lookup method: It requires large storage resources. For the LTE system, the lookup table has a capacity of 2 ^Λ 16*7ΐώ and requires 56 Μ9Κ Memory Blocks.

(2) Calculation method: Since the A-law calculation formula includes logarithmic and multiplication and division operations, it is very difficult to implement through logic circuits. At present, FPGA chip manufacturers provide IP cores for logarithmic operation and multiplication and division operations, which can calculate the calculation process, but have a long calculation cycle and occupy DSP (Digital Signal Processing) resources. Taking Altera's FPGA as an example, a logarithmic operator will occupy 8 DSPs, and a multiply operator will occupy 4 DSPs.

(3) Linear approximation: The calculation results have limited precision and poor flexibility. Different A values require different fold lines to approximate. The IR interface bit compression algorithm may change the value of A in different scenarios.

It can be seen that the current A-law compression algorithm is difficult to meet system requirements in terms of implementation difficulty and resource occupation. Summary of the invention

The embodiment of the present application provides an LTE-IR interface data compression method and device thereof, which are used to reduce technical implementation difficulty and reduce resource occupation.

In the LTE-IR interface data compression method applied to the distributed base station, the distributed base station is provided with a lookup table, and the process of creating the lookup table includes: The value range after taking the absolute value is divided into 2 ^N numerical intervals, where N is the bit width after the symbol is removed from the compressed data; a value in each numerical interval is used as the identification value of the numerical interval in ascending or descending order. The order is stored in the lookup table, and the address of each identifier value in the lookup table is a compression result value of the data to be compressed in the corresponding value interval; the method includes:

Receiving input data to be compressed;

Taking the absolute value of the data to be compressed, and storing the sign bit of the data to be compressed;

Using a binary search method, searching for the identification value of the numerical interval to which the absolute value of the data to be compressed belongs belongs in the lookup table;

Determining a compression result value of the data to be compressed according to an address of the identifier value of the found value interval in the lookup table;

And compressing the compressed result value of the data to be compressed into a signed number according to the sign bit of the data to be compressed.

The LTE-IR interface data compression device applied to the distributed base station provided by the embodiment of the present application includes:

The ROM module is configured to store a lookup table. The process of creating the lookup table includes: dividing a value range after the absolute value of the data to be compressed into 2 ^N value intervals, where N is a bit after the compressed data is removed from the symbol bit. Width; a value in each numerical interval as the identification value of the numerical interval is stored in the lookup table in ascending or descending order, and the address of each identification value in the lookup table is the compression result of the data to be compressed within the corresponding numerical interval. value;

An input module configured to receive input data to be compressed;

a first processing module, configured to take an absolute value of the data to be compressed, and save a sign bit of the data to be compressed;

a table lookup module configured to use a binary search method to search for an identifier value of a value interval of the absolute value of the data to be compressed in the lookup table; and, in the lookup table, according to the identifier value of the found value interval Address, determining a compression result value of the data to be compressed;

a second processing module, configured to: the data to be compressed according to the sign bit of the data to be compressed The compressed result value is converted to a signed number;

And an output module configured to output the signed number processed by the second processing module.

The embodiment of the present application further provides a BBU in a distributed base station device, including an uplink data processing module and a downlink data processing module, where the uplink data processing module includes an IR interface module, a decompression module, an AGC module, and a baseband. The module, the downlink data processing module includes: an IR interface module, a compression module, an AGC module, and a baseband module, wherein the compression module in the downlink processing module is the foregoing device.

The embodiment of the present application further provides an RRU in a distributed base station device, including an uplink data processing module and a downlink data processing module, where the uplink data processing module includes a radio frequency intermediate frequency module,

The AGC module, the compression module, and the IR interface module, the downlink data processing module includes: a radio frequency intermediate frequency module, a solution AGC module, a decompression module, and an IR interface module, wherein the compression module in the uplink processing module is the foregoing device.

The above embodiment of the present application divides the value range after the absolute value of the data to be compressed and removes the sign bit into 2 ^N numerical intervals, where N is the bit width of the compressed data; A value in the numerical interval is stored in the lookup table as the identification value of the numerical interval in ascending or descending order, and the address of each identification value in the lookup table is the compression result value of the data to be compressed in the corresponding numerical interval, and The binary search method is adopted for data compression based on the lookup table, thereby realizing the combination of the binary search method and the data compression look-up table method, thereby reducing the technical implementation difficulty and reducing resource occupation. DRAWINGS

1 is a structural diagram of a data frame of an LTE-IR interface with a word length T in the prior art;

2 is a schematic structural diagram of data compression of an IR interface in the prior art;

FIG. 3 is a schematic diagram of a data compression process of an LTE-IR interface according to an embodiment of the present application;

4 is a schematic diagram of a working principle of an A-law compression pipeline provided by an embodiment of the present application;

5 is a schematic diagram of a data format of an LTE-IR interface in the prior art; FIG. 6 is a schematic diagram of a data format of an LTE-IR interface according to an embodiment of the present disclosure;

FIG. 7 is a schematic structural diagram of an LTE-IR interface data compression apparatus according to an embodiment of the present application. detailed description

For the problems existing in the prior art, the embodiment of the present application proposes an LTE-IR interface data compression scheme, which can compress 16-bit baseband IQ data into 7-bit transmission (the compressed data does not need to be bitO discarded), thereby The amount of IQ data transmitted by the basic frame is doubled, the transmission rate is reduced, and finally, the amount of fiber is reduced by half, and the cost of the fiber is doubled. The compression scheme of the LTE-IR interface data provided by the embodiment of the present application can be implemented on an FPGA.

The LTE-IR interface data compression algorithm can be divided into four steps: AGC processing, A-law compression, decompression, and AGC. The AGC processing, the solution AGC, and the decompression implement the cartridge, so the embodiment of the present application adopts a conventional mature solution for the three steps, and will not be described here. A-law compression is the core part of LTE-IR interface data compression, and it is also a difficult point of FPGA implementation. On the basis of the existing implementation method, the embodiment of the present application optimizes the look-up table method, and uses the binary search method and the existing table lookup table. The method of combining the methods, in the case of ensuring that the compression ratio of the data is not lower than that, the A-law compression algorithm is implemented in a less resource-intensive manner. The A-law compression algorithm provided by the embodiment of the present application can support the data format before compression as Q (16, 1), and the compressed data format is Q (7, 1, 1). Further, the embodiment of the present application further optimizes the transmission format of the compressed data to improve the applicable range of the compression algorithm.

The A-law compression is symmetrical, so the absolute value portion of the compressed data can be compressed first, followed by the sign bit extension. The sign bit is removed, the compressed data is 6 bits, and the data ranges from 0 to 63. Each compressed data corresponds to a plurality of pre-compressed data within a range of values.

According to the above features, in the embodiment of the present application, the bit width N=6 after removing the sign bit according to the compressed data, and the entire value range after the absolute value of the data to be compressed is taken as 2 ^N =64 consecutive value intervals, each will be The value of the starting position of the numerical interval (hereinafter referred to as the starting point value) is stored in the lookup table (ROM table) in ascending order, and the address of each starting point value in the ROM table is the compression result value of the data to be compressed in the corresponding numerical interval. The size of the table is 2 ⁶ * 15 bits. In this way, as long as the data to be compressed is determined by looking up the table The numerical interval of the genus can obtain the corresponding compressed data.

In each lookup operation, there are two branch jump results (ie, the search is successful or unsuccessful). If all the conditional judgment logic is listed, then 64 judgment statements (such as if... else... statement) are required. The logic circuit of this method is redundant and complicated, and too many judgment statements are nested, which causes the critical path to become long and difficult to pass through the layout. In order to solve the problem, the embodiment of the present application uses a binary search method to determine the numerical interval to which the data to be compressed belongs by looking up the table.

Two-point search is also called half-fold search. The advantage is that the number of comparisons is small, the search speed is fast, and the average performance is good. Assume that the elements in the table are sorted in ascending order, and compare the keywords recorded in the middle position of the table with the search keywords. If the two are equal, the search is successful; otherwise, the intermediate position record is used to divide the table into two sub-tables, if the middle If the keyword of the location record is larger than the search keyword, the previous child table is further searched, otherwise the next child table is further searched. Repeat the above process until you find a record that meets the criteria, making the lookup successful, or until the child table does not exist. For the embodiment of the present application, the keyword recorded in the table is the starting value of each of the 64 data intervals, and the search keyword is the absolute value of the data to be compressed.

The embodiment of the present application adopts a binary search method, and for a data to be compressed, at most N=6 (N is a compressed data bit width, excluding a sign bit, and a sign bit occupies 1 bit), and the table can be determined and determined. The data interval to which the compressed data belongs.

Based on the above lookup table (ROM table), FIG. 3 shows a LTE-IR interface data A-law compression process provided by an embodiment of the present application. Corresponding to the structural principle diagram of the IR interface data compression shown in Fig. 2, the flow is implemented in a compression module in the distributed base station RRU and BBU. As shown, the process can include:

Step 301: Receive input data to be compressed.

Step 302: Take the absolute value of the data to be compressed, and save the sign bit of the data to be compressed. Step 303: Search for the starting value of the value range of the absolute value of the data to be compressed in the ROM table by using a binary search method;

Step 304: Determine, according to an address of the found value of the found value interval in the ROM table, a compression result value of the data to be compressed. Step 305: Convert the compression result value of the data to be compressed into a signed number according to the sign bit of the data to be compressed, and output the result.

The implementation process of step 303 of the foregoing process may be: comparing the starting value stored in the middle position of the ROM table with the absolute value of the data to be compressed, and if the two are equal, ending the searching process; otherwise, the ROM table is taken at the intermediate position Dividing into two sub-tables, if the starting value stored in the intermediate position is greater than the absolute value of the data to be compressed, further searching for the previous sub-table, otherwise searching for the next sub-table, and so on, until the two are equal or The search process ends until the first or last start value stored in the ROM table is found. Wherein, when searching in the sub-table, comparing the starting value stored in the middle position of the sub-table with the absolute value of the data to be compressed, if the two are equal, the searching process is ended; otherwise, the sub-location is the intermediate position The table is further divided into two sub-tables. If the starting value stored in the intermediate position is greater than the absolute value of the data to be compressed, the previous sub-table is further searched, otherwise the next sub-table is further searched.

When the search result is equal to the two or finds the first starting value stored in the ROM table, the current starting value is taken as the starting value of the numerical interval to which the absolute value of the data to be compressed belongs. When the last starting value stored in the ROM table is found, if the identification value is greater than the absolute value of the data to be compressed, the previous starting value of the identification value is used as the starting value of the numerical interval to which the absolute value of the data to be compressed belongs. Otherwise, the current starting point value is taken as the starting point value of the numerical interval to which the absolute value of the data to be compressed belongs.

In the specific implementation, considering the value range of the compressed data is 0~63, the value range of the address space of the ROM table is also set to 0~63. The specific implementation process of the foregoing steps 303-304 may be: First, the address bit variable add of the ROM table is set, and the initial value is set to 31. After receiving the input data to be compressed and taking the absolute value (denoted as abs_data) and saving the sign bit, perform the following table lookup operation as follows:

Step 3031: Read the starting point value stored in the address in the ROM table according to the current address variable add=31 and assign the variable dout to compare the abs_data with the dout; if the abs_data>dout, add the address variable add to 16, and go to the step 3032; If abs_data <dout, the address variable add is decremented by 16 and the process proceeds to step 3032; if abs_data=dout, then the process proceeds to step 3037a. Step 3032, according to the current address variable add read the starting point value stored in the address of the ROM table and assign the variable dout, compare abs_data with dout; if abs_data>dout, add the address variable add 8, and then proceeds to step 3033; If abs_data <dout, the address variable add is decremented by 8 and the process proceeds to step 3033. If abs_data=dout, the process proceeds to step 3037a.

Step 3033, according to the current address variable add read the starting point value stored in the ROM table and assign the variable dout, compare abs_data with dout; if abs_data>dout, then add the address variable add 4, and proceeds to step 3034; If abs_data <dout, the address variable add is decremented by 4, and the process proceeds to step 3034. If abs_data=dout, the process proceeds to step 3037a.

Step 3034, according to the current address variable add read the starting point value stored in the ROM table and assign the variable dout, compare abs_data and dout; if abs_data>dout, add the address variable add 2, and proceeds to step 3035; If abs_data <dout, the address variable add is decremented by 2, and the process proceeds to step 3035. If abs_data=dout, the process proceeds to step 3037a.

Step 3035, according to the current address variable add read the starting point value stored in the ROM table and assign the variable dout, compare abs_data with dout; if abs_data>dout, then add the address variable add, and then proceeds to step 3036; If abs_data <dout, the address variable add is decremented by 1 and the process proceeds to step 3036; if abs_data=dout, the process proceeds to step 3037a.

Step 3036, according to the current address variable add read the starting point value stored in the address in the ROM table and assign the variable dout, compare abs_data with dout; if abs_data>dout, go to step 3037a; if abs_data <dout, then transfer Step 3037b.

In step 3037a, the address of the current starting point value in the ROM table is used as the compression result value of abs_data.

Step 3037b, the address value of the current starting point value in the ROM table is decremented by 1 as the compression result value of abs_data (that is, the address value of the previous starting point value is used as the compression result value of abs_data).

It can be seen from the above process that since the compressed data bit width is 6, the table lookup process of the A-law compression algorithm requires a maximum of 6 lookup operations (steps 3031 to 3036), and if the serial operation mode is adopted, the high speed cannot be satisfied. Data transmission requirements. Therefore, in another embodiment of the present application, the above table operation will be performed. The segmentation is done in a pipelined manner, which ensures that compressed data is output every clock cycle.

In the specific implementation, since the ROM table is read in steps 3031~3016, in the pipeline working mode, the same ROM cannot be read multiple times in one clock cycle, so six identical images can be created. The ROM tables (ROM1~6) are used for steps 3031~3036, respectively. For example, step 3031 uses ROM1, step 3032 uses ROM2, and so on, that is, the previous lookup operation for the same compressed data is different from the ROM table used for the subsequent lookup operation. In this way, since there are six ROM tables, six look-up tables can be executed in parallel in six ROM tables in one clock cycle, which improves data processing efficiency and data transmission efficiency.

Further, in another embodiment, considering the operation of step 3031, the value of the address variable add is an initial value, which is fixed, and it is not necessary to determine the value of the address variable add by looking up the table, so the step 3031 is The judgment operation can be implemented without the table lookup operation, so that one ROM table can be reduced, and five ROM tables can be created for use in steps 3032 to 3036, respectively. The structure of the pipeline working mode can be as shown in FIG. 4, wherein addrO and doutO respectively represent an initial address value 31 and an initial comparison value (the initial comparison value is a starting value stored on the initial address, and the two values are fixed. (The starting value stored in the initial address value 31 can be known in advance.) addrl to addr5 respectively indicate the input address of ROM1 to ROM5, and doutl to dout5 are the corresponding output comparison values (ie, the starting value stored on the corresponding address, such as doutl The starting point value stored on addrl).

It should be noted that in the actual implementation process, the ROM table usually has a delay of 2 clock cycles from address input to data output, and a complete compression process takes at least 18 clock cycles to achieve (including absolute input data). The step of value and the step of sign bit expansion of the compression result), so the pipeline operation is actually divided into 18 steps. Figure 4 is only a schematic structural diagram and does not represent a real structural diagram.

As can be seen from the above description, by using the binary table lookup method, in the case where the data bit width after compression is 6, only 6 or 5 M9K Memory Blocks are occupied, and 56 methods need to be used in the prior art lookup table method. Compared with the M9K Memory Block, the resource consumption is reduced. In addition, from the implementation It can be seen that the two-point look-up table method is also cleaner than the calculation method in the prior art. Therefore, the comprehensive performance of the two-point look-up table method is superior to the three existing A-law compression methods. Further, for different values of A, in the embodiment of the present application, only the initialization data file of the ROM table can be modified for the binary table lookup method, which is more flexible and more applicable than the linear approximation method in the prior art.

As can be seen from Figure 2, the upstream compression module is added before the BBU's IR interface module, and the downstream compression module is added before the RRU's IR interface module. For the existing base station equipment, the input data format of the BBU downlink IR interface and the RRU uplink IR interface is as shown in Figure 5 (taking 20M8A as an example, where A is the antenna, S is the sampling point), and an AxSx is 30 bits wide, including 15bit I data and 15bit Q data (bitO bits of I/Q data are discarded). In the IR interface bit compression mode, the compression module AxSx is 14 bits (7bitl data + 7bitQ data). If the compression module outputs the compressed data directly to the IR interface module, the effective input bit width of the IR interface becomes 14bit. This requires corresponding modifications within the IR interface module. In addition, since the data is processed by AGC before compression, the corresponding AGC factor value needs to be transmitted to the solution AGC module via the IR interface to restore the data amplitude.

In the other embodiment of the present application, the compression module compresses data of two adjacent sampling points of the same antenna in consideration of the above data transmission requirements, in order to minimize the impact of the IR interface compression module on the base station device. (that is, the data after compression and sign bit expansion) are put together and output to the IR interface module. Further, the remaining 2 bits can also transmit the AGC factor of the antenna. The format of the output data of the compression module can be as shown in Figure 6. Since the amount of data after splicing is halved, the output data is not always valid, but 8 valid and 8 invalid. Invalid data is discarded in the IR interface module through a certain processing flow.

Through the splicing of the AGC factor and the compressed data, the data format input to the IR interface module is equivalent to no change, and its bit width is 30 bits, which avoids the modification of the IR interface module and is beneficial to the upgrading of the existing base station equipment.

Based on the same technical concept, the embodiment of the present application further provides an LTE-IR interface data compression apparatus, which can be applied to a distributed base station, and corresponds to a compression module in the structure shown in FIG. 2. FIG. 7 is a schematic structural diagram of an LTE-IR interface data compression apparatus according to an embodiment of the present disclosure, where the apparatus may include:

The ROM module 701 is configured to store a lookup table. The process of creating the lookup table includes: dividing the value range after the absolute value of the data to be compressed into 2 ^N value intervals, where N is the compressed data after the sign bit is removed. Bit width; a value in each numerical interval is stored as an identification value of the numerical interval in an ascending or descending order in a lookup table, and each of the identification values in the lookup table is a compression of the data to be compressed within the corresponding numerical interval. Result value

The input module 702 is configured to receive the input data to be compressed;

The first processing module 703 is configured to take an absolute value of the data to be compressed, and save a sign bit of the data to be compressed.

The lookup table module 704 is configured to use a binary search method to search for an identifier value of a value interval of the absolute value of the data to be compressed in the lookup table; and, in the lookup table, according to the identifier value of the found value interval The address in the medium, determining a compression result value of the data to be compressed;

The second processing module 705 is configured to convert the compressed result value of the data to be compressed into a signed number according to the sign bit of the data to be compressed.

The output module 706 is configured to output the signed number processed by the second processing module 707.

Specifically, the identification value of each numerical interval is a starting position value of the numerical interval, and the identification values of each numerical interval are stored in the lookup table in ascending order. Correspondingly, the lookup table module 704 compares the identifier value stored in the middle position of the lookup table with the absolute value of the data to be compressed, and if the two are equal, ends the search process; otherwise, the search is performed at the intermediate position The table is divided into two sub-tables, and if the identifier value stored in the intermediate location is greater than the absolute value of the data to be compressed, the previous sub-table is further searched, otherwise the next sub-table is further searched, and so on, until both Equal or until the first or last identity value stored in the lookup table is found, the search process ends;

Wherein, when searching in the sub-table, comparing the identifier value stored in the middle position of the sub-table with the absolute value of the data to be compressed, if the two are equal, the search process is ended; otherwise, the intermediate position is used The child table is further divided into two front and a back child tables, if the intermediate location stores an identifier value greater than the If the absolute value of the data to be compressed is further, the previous sub-table is further searched, otherwise the next sub-table is further searched; when the search result is equal to the two or the first identification value stored in the lookup table is found, the current identification value is obtained. An identification value of a numerical interval to which the absolute value of the data to be compressed belongs;

When the last identifier value stored in the lookup table is found, if the identifier value is greater than the absolute value of the data to be compressed, the previous identifier value of the identifier value is used as the absolute value of the data to be compressed. The identifier value of the interval; otherwise, the current identifier value is used as the identifier value of the value interval to which the absolute value of the data to be compressed belongs.

Specifically, the number of the lookup tables is N. Correspondingly, the lookup table module 704 is specifically configured to: perform, according to the N lookup tables, the number of data to be compressed that does not exceed N in parallel; wherein, the previous search operation for the same data to be compressed and the subsequent search The lookup table used by the operation is different.

Specifically, the number of the lookup tables is N-1. Correspondingly, the look-up table module 704 is specifically configured to: perform, according to the N-1 lookup tables, the number of data to be compressed that does not exceed N in parallel; wherein, for the data to be compressed, except for the first search operation Other lookup operations, using a lookup table, and the previous lookup operation for the same data to be compressed is not the same as the lookup table used by the latter lookup operation.

Further, the output module 706 further splices the signed compressed data of at least two sampling points adjacent to the same antenna before outputting the signed number, and the bit width of the spliced data does not exceed the LTE-IR interface. The data width is wide.

Further, the output module 706 uses the remaining bits to carry the automatic gain control AGC factor of the corresponding antenna when the bit width of the spliced data is smaller than the LTE-IR interface data bit width.

Specifically, the compression result value of the data to be compressed is calculated according to an A-law compression algorithm, and the N is equal to 6.

The embodiment of the present application further provides a BBU in a distributed base station device. Specifically, the BBU includes an uplink data processing module and a downlink data processing module, where the uplink data processing module includes an IR interface module, a decompression module, a solution AGC module, and a baseband module, and the downlink data processing module The blocks include: IR interface module, compression module, AGC module, baseband module. The compression module in the downlink processing module has the structure and function as shown in FIG. 7, that is, can be implemented by using the apparatus shown in FIG.

The embodiment of the present application further provides an RRU in a distributed base station device. Specifically, the RRU includes an uplink data processing module and a downlink data processing module, where the uplink data processing module includes a radio frequency intermediate frequency module, an AGC module, a compression module, and an IR interface module, and the downlink data processing module includes: a radio frequency intermediate frequency module The AGC module, the decompression module, and the IR interface module are solved. The compression module in the upstream processing module has the structure and function as shown in FIG. 7, that is, it can be implemented by the device shown in FIG.

In summary, the embodiment of the present application implements an IR interface bit compression algorithm based on A-law compression, which can compress I/Q data from 16 bits to 7 bits under the premise of small signal loss, thereby saving half of the fiber cost. . In addition, the output data transmission format of the compression module to the IR interface module remains unchanged, which is beneficial to upgrade existing base stations.

It should be noted that, in the above embodiment of the present application, the design of the lookup table and the corresponding table lookup operation are described by taking the starting value of the value interval in ascending order in the lookup table as an example, but the application is implemented. The example is not limited to this. For example, the starting point value of the numerical interval may be stored in the lookup table in descending order, or the end point value of the numerical interval may be stored in the lookup table in descending order, etc. According to the design of the lookup table, the table lookup operation needs to be adjusted accordingly.

In addition, the above embodiment of the present application is described by taking an A-law compression algorithm as an example. For a similar compression algorithm, data compression may also be implemented according to the compression method provided by the embodiment of the present application.

Those skilled in the art can understand that the modules in the apparatus in the embodiments may be distributed in the apparatus of the embodiment according to the description of the embodiments, or the corresponding changes may be located in one or more apparatuses different from the embodiment. The modules of the above embodiments may be combined into one module, or may be further split into a plurality of sub-modules.

Correspondingly, the embodiment of the present application further provides a computer readable recording medium on which a program for executing the LTE-IR interface data compression method applied to a distributed base station is recorded. The computer readable recording medium includes any mechanism for storing or transmitting information in a form readable by a computer (eg, a computer). For example, a machine-readable medium includes a read only memory (ROM), a random access memory (RAM), a magnetic disk storage medium, an optical storage medium, a flash storage medium, an electrical, optical, acoustic, or other form of propagated signal (eg, a carrier wave) , infrared signals, digital signals, etc.).

Through the description of the above embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary general hardware platform, and of course, can also be through hardware, but in many cases, the former is a better implementation. the way. Based on such understanding, the technical solution of the present application, which is essential or contributes to the prior art, may be embodied in the form of a software product stored in a storage medium, including a plurality of instructions for causing a The terminal device (which may be a mobile phone, a personal computer, a server, or a network device, etc.) performs the methods described in the various embodiments of the present application.

The above description is only a preferred embodiment of the present application, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present application. The scope of protection of this application shall be considered.

Claims

Claim

A LTE-IR interface data compression method for a distributed base station, wherein the distributed base station is provided with a lookup table, and the process of creating the lookup table includes: after taking the absolute value of the data to be compressed The value range is divided into 2 ^N numerical intervals, where N is the bit width after the symbol is removed from the compressed data; a value in each numerical interval is stored as an identification value of the numerical interval in ascending or descending order. The table, the address of each identifier value in the lookup table is a compressed result value of the data to be compressed in the corresponding value interval; the method includes:

Receiving input data to be compressed;

2. The method according to claim 1, wherein the identification value of each numerical interval is a starting position value of the numerical interval, and the identification values of each numerical interval are stored in a lookup table in ascending order; The step of searching for the identifier value of the numerical interval to which the absolute value of the data to be compressed belongs is found in the lookup table by using a binary search method, including:

Comparing the identifier value stored in the middle position of the lookup table with the absolute value of the data to be compressed, if the two are equal, ending the searching process; otherwise, dividing the lookup table into the front and back by the intermediate position a table, if the identifier value stored in the intermediate location is greater than an absolute value of the data to be compressed, further searching for a previous sub-table, otherwise searching for a subsequent sub-table, and so on, until the two are equal or until the Ending the search process when searching for the first or last identifier value stored in the table; wherein, when performing the lookup in the child table, comparing the identifier value stored in the middle position of the child table with the absolute value of the data to be compressed, if If the two are equal, the search process ends; otherwise, the middle Positioning the sub-table into the previous two sub-tables. If the value stored in the intermediate location is greater than the absolute value of the data to be compressed, the previous sub-table is further searched, otherwise the subsequent sub-table is further searched; If the result is that the two are equal or find the first identifier value stored in the lookup table, the current identifier value is used as the identifier value of the value interval to which the absolute value of the data to be compressed belongs;

The method of claim 1, wherein the number of the lookup tables is N, and a binary search method is used, and the identifier of the numerical interval to which the absolute value of the data to be compressed belongs is searched in the lookup table. In the case of a value, the search is performed in parallel on the data to be compressed that does not exceed N according to the N lookup tables, wherein the previous search operation for the same data to be compressed is different from the lookup table used by the subsequent search operation. .

The method according to claim 1, wherein the number of the lookup tables is N-1, and a binary search method is used, and the value range of the absolute value of the data to be compressed is searched in the lookup table. And performing the searching according to the N-1 lookup tables in parallel for the number of data to be compressed that does not exceed N; wherein, for the search operation other than the first search operation, the data to be compressed is used for searching. The table, and the previous lookup operation for the same data to be compressed is not the same as the lookup table used by the latter lookup operation.

The method according to claim 1, wherein after converting the compressed result value of the data to be compressed into a signed number and outputting the signed number, the method further includes:

The signed compressed data of at least two sampling points adjacent to the same antenna are spliced together, and the bit width of the data spliced together does not exceed the data bit width of the LTE-IR interface.

6. The method according to claim 5, wherein if the bit width of the data spliced together is smaller than the LTE-IR interface data bit width, the remaining bits are used to carry the automatic gain control AGC factor of the corresponding antenna.

The method according to any one of claims 1 to 5, characterized in that the compression result value of the data to be compressed is calculated according to an A-law compression algorithm, and the N is equal to 6.

8. An LTE-IR interface data compression apparatus for a distributed base station, comprising:

An input module configured to receive input data to be compressed;

The second processing module is configured to convert the compressed result value of the data to be compressed into a signed number according to the sign bit of the data to be compressed;

9. The apparatus according to claim 8, wherein the identification value of each numerical interval is a starting position value of the numerical interval, and the identification values of each numerical interval are stored in the lookup table in ascending order;

The table lookup module is configured to compare the identifier value stored in the middle position of the lookup table with the absolute value of the data to be compressed, and if the two are equal, the search process ends; otherwise, the intermediate location is The lookup table is divided into two preceding and succeeding sub-tables. If the identifier value stored in the intermediate location is greater than the absolute value of the data to be compressed, the previous sub-table is further searched, otherwise the subsequent sub-table is further searched, and so on, until The two are equal or until the first or last label stored in the lookup table is found End the search process when identifiable;

Wherein, when searching in the sub-table, comparing the identifier value stored in the middle position of the sub-table with the absolute value of the data to be compressed, if the two are equal, the search process is ended; otherwise, the intermediate position is used The sub-table is further divided into two sub-tables. If the value stored in the intermediate location is greater than the absolute value of the data to be compressed, the previous sub-table is further searched, otherwise the subsequent sub-table is further searched; When the first identifier value stored in the lookup table is equal or found, the current identifier value is used as an identifier value of the value interval to which the absolute value of the data to be compressed belongs;

The apparatus according to claim 8, wherein the number of the lookup tables is N; the lookup table module is specifically configured to: the number of parallel pairs of the N lookup tables not exceeding N respectively Compressing the data performs the lookup; wherein the previous lookup operation for the same data to be compressed is different from the lookup table used by the latter lookup operation.

The apparatus according to claim 8, wherein the number of the lookup tables is N-1; the lookup table module is specifically configured to: the number of parallel pairs according to the N-1 lookup tables respectively exceed

The data to be compressed is subjected to the search; wherein, for the search operation other than the first search operation, the lookup table is used, and the previous search operation for the same data to be compressed is used with the subsequent search operation The lookup table is not the same.

12. The apparatus according to claim 8, wherein the output module is further configured to splicing the signed compressed data of at least two sampling points adjacent to the same antenna before outputting the signed number. Together, the bit width of the data stitched together does not exceed the data bit width of the LTE-IR interface.

The device according to claim 12, wherein the output module is further configured to: when the bit width of the spliced data is smaller than the LTE-IR interface data bit width, use the remaining bits to carry the corresponding The automatic gain control of the antenna controls the AGC factor.

The apparatus according to any one of claims 8-13, characterized in that the compression result value of the data to be compressed is calculated according to an A-law compression algorithm, and the N is equal to 6.

A baseband unit BBU in a distributed base station device, comprising an uplink data processing module and a downlink data processing module, wherein the uplink data processing module comprises an IR interface module, a decompression module, an AGC module, and a baseband module. The downlink data processing module includes: an IR interface module, a compression module, an AGC module, and a baseband module, wherein the compression module in the downlink processing module is the device according to claim 8.

A radio remote device RRU in a distributed base station device, comprising an uplink data processing module and a downlink data processing module, wherein the uplink data processing module comprises a radio frequency intermediate frequency module, an AGC module, a compression module, and an IR interface module, The downlink data processing module includes: a radio frequency intermediate frequency module, a de-AGC module, a decompression module, and an IR interface module, wherein the compression module in the uplink processing module is the device according to claim 8.

A computer readable recording medium having recorded thereon a program for executing the method of claim 1.