CN100364250C - Delay Compensation Method and System Used in Mobile Communications - Google Patents

Abstract

The invention relates to mobile communication, and discloses a delay compensation method and system used in mobile communication, which can ensure the synchronization of wireless frames of each sub-district of a base station at the antenna port. In this delay compensation method used in mobile communication, first obtain the respective total delays of the data transmission paths of each cell from the baseband processing unit to the antenna port, and then pass through the baseband processing unit and the intermediate frequency processing unit respectively to transmit data through the corresponding path Integer-level and fractional-level delay compensation for cell data.

Description

Delay Compensation Method and System Used in Mobile Communications

technical field

The invention relates to mobile communication, in particular to a synchronization technique for keeping wireless frames of each sub-district of a base station at an antenna port in a mobile communication system.

Background technique

With the development of high technology marked by communication technology and computer technology, people's lives have undergone tremendous changes with each passing day, and the information transmission between people is getting closer and more diverse. Mobile communication is one of the main ways of information transmission that brings many conveniences to people, and it is still developing rapidly to meet people's growing needs for high-speed data access.

In a mobile communication system, it is often required that the wireless frames of each cell of the base station can be synchronized at the antenna port. The reason is that the level of synchronization accuracy may affect the mobile phone's synchronous reception performance of multiple cells, transmit diversity consistency and loop Transmission delay (Round Trip Time, referred to as "RTT") measurement, etc. Those skilled in the art know that, taking the Wideband Code Division Multiple Access (WCDMA for short) communication system as an example, a wireless frame is a chip combination specified in the protocol, and a chip is a measure of the WCDMA system. A basic identification of the physical channel time length of a WCDMA system. The physical channel time length in a WCDMA system is usually identified by an integer number of chips. For example, a radio frame usually includes 15 time slots, and each time slot includes 2560 chips, so it can be seen that a radio frame usually consists of 38400 chips.

However, the wireless frames of each cell in a general base station cannot be completely synchronized at the antenna port. The main reason is that the downlink transmission of data may pass through different routing channels, and the delays between the processing units in each routing channel and the channels between processing units are inconsistent. The radio frame delay of the radio is inconsistent. In order to illustrate this problem more clearly, it will be explained below with reference to FIG. 1 .

FIG. 1 is a schematic diagram of delays of processing units of a base station and channels between them. As shown in the figure, the initial synchronization time of the entire system is generally controlled by the timing bus 10, and then the baseband processing unit 11, data forwarding unit 12, intermediate frequency processing unit 120, radio frequency processing unit 121, and antenna 122 form the first cell data transmission path. The baseband processing unit 11 , the data forwarding unit 12 , the intermediate frequency processing unit 123 , the radio frequency processing unit 124 , and the antenna 125 form the second cell data transmission path.

Where T1 represents the unit channel delay time between the baseband processing unit 11 and the data forwarding unit 12, T5 is the unit channel delay time between the data forwarding unit 12 and the intermediate frequency processing unit 120, and T9 is the intermediate frequency processing unit 120 and the radio frequency processing unit 121 T13 is the unit channel delay time between the radio frequency processing unit 121 and the antenna 122 .

T6 is the unit channel delay time between the data forwarding unit 12 and the intermediate frequency processing unit 123, T10 is the unit channel delay time between the intermediate frequency processing unit 123 and the radio frequency processing unit 124, and T14 is the unit channel delay between the radio frequency processing unit 124 and the antenna 125 time.

T17 represents the delay time of the data forwarding unit 12, T18 and T20 represent the delay times of the IF processing unit 120 and the IF processing unit 123, respectively, and T19 and T21 represent the delay times of the RF processing unit 121 and the RF processing unit 124, respectively.

The third cell data transmission path is composed of baseband processing unit 13, data forwarding unit 14, intermediate frequency processing unit 140, radio frequency processing unit 141, antenna 142, and the fourth cell data transmission path is composed of baseband processing unit 13, data forwarding unit 14, It consists of an intermediate frequency processing unit 143 , a radio frequency processing unit 144 , and an antenna 145 .

Similar to the data transmission paths of the first two cells, T4 represents the unit channel delay time between the baseband processing unit 13 and the data forwarding unit 14, T7 is the unit channel delay time between the data forwarding unit 14 and the intermediate frequency processing unit 140, and T11 is The unit channel delay time between the IF processing unit 140 and the radio frequency processing unit 141 , T15 is the unit channel delay time between the radio frequency processing unit 141 and the antenna 142 .

T8 is the unit channel delay time between the data forwarding unit 14 and the intermediate frequency processing unit 143, T12 is the unit channel delay time between the intermediate frequency processing unit 143 and the radio frequency processing unit 144, and T16 is the unit channel delay between the radio frequency processing unit 144 and the antenna 145 time.

T22 represents the delay time of the data forwarding unit 14, T23 and T25 represent the delay times of the IF processing unit 140 and the IF processing unit 143, respectively, and T24 and T26 represent the delay times of the RF processing unit 141 and the RF processing unit 144, respectively.

In fact, there is also a channel between the baseband processing unit 11 and the data forwarding unit 14, and T2 represents the channel delay time between the two. Similarly, there is also a channel between the baseband processing unit 13 and the data forwarding unit 12, and T3 represents the channel delay between the two. time. In this way, more cell data transmission paths can also be combined.

It can be seen that since data downlink transmission may have different paths, and the delay of different processing units may also be different, even if it is the data transmission path of the cell connected under the same baseband processing unit and data forwarding unit, each processing unit and processing The delay times of the channels between the units are also not all the same. To illustrate with a few examples, the dotted lines in the figure represent the data transmission paths of different cells. Although the cell data transmission path 15 and the cell data transmission path 17 pass through the same baseband processing unit 11 and the data forwarding unit 12 at the same time, the intermediate frequency processing unit 120, the radio frequency processing unit 121, and the antenna 122 pass through behind the cell data transmission path 15. The intermediate frequency processing unit 123, the radio frequency processing unit 124, and the antenna 125 are passed behind the data transmission path 17. Any one of the processing units in the two different routes or the delay between the channels between the processing units are different, which will cause the routing channel 15 to be different from the routing channel. The total delay of the radio frame of 17 is different. And pass through the baseband processing unit 13 and the data forwarding unit 12 together, and respectively pass through the cell data transmission path 16 of the intermediate frequency processing unit 120, the radio frequency processing unit 121, the antenna 122 and pass through the intermediate frequency processing unit 123, the radio frequency processing unit 124, the antenna 125 separately Compared with the previous two cell data transmission paths 18, the cell data transmission path 18 also encounters the situation that the total delay of the radio frame is different.

In view of the problems raised above, it can be understood that certain measures need to be taken to achieve wireless frame synchronization of each cell at the antenna port, so as to ensure the synchronous reception performance of the mobile phone for multiple cells and the consistency of transmit diversity, and to ensure RTT measurement, but until No satisfactory solution has been proposed so far.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a delay compensation method and system for mobile communication, so as to ensure the synchronization of the radio frames of each cell of the base station at the antenna port.

To achieve the above object, the present invention provides a delay compensation method used in mobile communications, comprising the following steps:

Obtain the respective total delays of the data transmission paths of each cell from the baseband processing unit to the antenna port; the baseband processing unit and the intermediate frequency processing unit perform delay compensation on the cell data transmitted through the corresponding paths according to the respective total delays of the data transmission paths .

Wherein, the baseband processing unit performs integral-level delay compensation on the cell data in units of chips, and the intermediate frequency processing unit performs fractional-level delay compensation on the cell data in units of chips.

The baseband processing unit performs integer-level delay compensation through a shift register group.

The intermediate frequency processing unit performs fractional delay compensation through a shift register group, wherein a clock of the shift register group is higher than a chip rate.

The intermediate frequency processing unit performs fractional delay compensation through a digital filter.

The present invention also provides a delay compensation system, which includes a baseband processing unit, a data forwarding unit, an intermediate frequency processing unit, a radio frequency processing unit, and an antenna that sequentially process cell data, and the baseband processing unit and the intermediate frequency processing unit also include The delay compensation circuit is used to compensate the pre-measured total delay of the data transmission path of each cell from the baseband processing unit to the antenna port.

Wherein, the delay compensation circuit in the baseband processing unit is used to perform integer-level delay compensation in units of chips; the delay compensation circuit in the intermediate frequency processing unit is used to perform fractional delays in units of chips compensate.

The delay compensation circuit in the baseband processing unit is composed of a shift register group.

The delay compensation circuit in the intermediate frequency processing unit is composed of a shift register group, wherein the clock of the shift register group is higher than the chip rate.

The delay compensation circuit in the intermediate frequency processing unit is composed of a digital filter.

Through comparison, it can be found that the difference between the technical solution of the present invention and the prior art is that, according to the predetermined total delay of the data transmission path of each cell from the baseband processing unit to the antenna port, the baseband processing unit performs integer-level delay compensation, Fractional delay compensation is performed through the IF processing unit.

The difference in this technical solution brings obvious beneficial effects, that is, the purpose of better realizing the synchronization of the radio frames of the various cells of the base station at the antenna port.

Description of drawings

FIG. 1 is a schematic diagram of delays between processing units and channels between processing units of a base station in the prior art;

Fig. 2 is a flowchart of delay compensation according to an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

Generally speaking, the principle of the present invention is: by performing integer-level delay compensation in the baseband processing unit and fractional-level delay compensation in the intermediate frequency processing unit, the wireless frame synchronization of each cell of the antenna port of the base station is realized.

In order to ensure the synchronization of the wireless frames of the various cells of the base station at the wireless interface, the present invention implements a complete technical solution according to three major steps. The following will describe in detail with reference to FIG. 1 and FIG. 2 .

First, in step 200, the total channel delay from the baseband processing unit to the antenna port is acquired. Specifically, it is subdivided into two sub-steps.

The first sub-step is to obtain the delay of each processing unit and the transmission channel between processing units through design constraints, real-time measurement and data configuration. Taking Figure 1 as an example, in this sub-step, each value from T1 to T26 should be accurately obtained.

In the next second sub-step, the total delay of each cell's data transmission path from the baseband processing unit to the antenna port is determined. Still taking Figure 1 as an example, if it is the cell data transmission path 15, the total delay is the sum of T1, T17, T5, T18, T9, T19, T13; and the total delay of the cell data transmission path 16 is T3, T17, The sum of T5, T18, T9, T19, T13; the total delay of the cell data transmission path 17 is the sum of T1, T17, T6, T20, T10, T21, T14; the total delay of the cell data transmission path 18 is T3, T18, Sum of T6, T20, T10, T21, T14.

If there are other routing channels, the total delay of the data transmission channel of the corresponding cell can be obtained by adding the delays of the processing units and the transmission channels between the processing units it passes through.

After obtaining the total delay of the data transmission path of each cell from the baseband processing unit to the antenna port, the next step is to compensate the channel delay of each cell. The compensation needs to be completed by the baseband processing unit and the intermediate frequency processing unit. The general implementation method is to send the data of each cell in advance in the baseband processing unit as needed. The advance amount is approximately equal to the total delay of the data transmission channel of each cell. The time is basically synchronized, that is, the baseband processing unit completes the rough adjustment function of delay compensation. Thereafter, the intermediate frequency processing unit completes the function of fine-tuning the delay of each cell. Referring to FIG. 2 , the details will be described below.

In step 210, the baseband processing unit completes the coarse adjustment of the delay compensation. In this step, the baseband processing unit completes integer-level delay compensation. Referring to FIG. 1, the delay compensation process of the integer level will be described below. In Figure 1, the data forwarding unit is often located between the baseband processing unit and the intermediate frequency processing unit. It works at the data link layer, and its function is to perform framing and deframing operations on the data of multiple cells. Therefore, based on the downlink data flow, The unit of time adjustment performed by the baseband processing unit in front of it should be the minimum unit of data combination of the multi-cell framing by the data forwarding unit.

As mentioned above, taking the WCDMA system as an example, one chip is the minimum unit for the data combination of data forwarding processing unit framing. Therefore, when the baseband processing unit transmits in advance for delay compensation, the compensation unit should also be one chip. Time, this kind of chip-based compensation is generally regarded as integer-level delay compensation.

The specific implementation of the integer-level delay compensation of the baseband processing unit is through sequential logic processing, and in this embodiment, the delay processing is completed through a shift register group. The above-mentioned shift register has a storage function and a shift function. Since shift operations are often used in digital systems, if necessary, the shift register can control the incoming data by storing and shifting, and output the required data stream.

Generally speaking, the clock period used by the shift register on the baseband processing unit is equal to the chip period, so adjusting the time length of one chip unit can be realized only by delaying the output of the shift register by one clock period. In some cases, it is possible that the shift register uses a higher clock frequency, and one chip cycle is equal to several clock cycles. At this time, it is only necessary to delay the shift register by a few beats.

Afterwards, enter step 220 to implement fine-tuning of the delay compensation of the intermediate frequency processing unit, that is, to complete fractional delay compensation.

The fractional delay compensation process will be described below with reference to FIG. 1 . First of all, it needs to be explained that in some cases, the compensation unit of the above-mentioned baseband processing unit is not the time of one chip. Specifically, due to the framing operation of the data forwarding unit, it is easy to cause additional errors, because the signal pulse time of each data bit is not equal to one chip, combining multiple data bits into a wireless frame may cause The unit processing time delay time of the data forwarding unit is not a time value whose basic unit is a chip.

In this case, the fractional level compensation needs to be completed in the intermediate frequency processing unit following the data unit. The fractional-level delay compensation of the IF processing unit is implemented in the case of low precision requirements, similar to the integer-level delay compensation of the baseband processing unit, which are all implemented through sequential logic processing of the shift register above each, that is, through delay processing. The difference between the two is that the clock rate of the time shift register on the IF processing unit is generally more than 10 times, or even dozens of times, the chip rate. Obviously, the time scale of the controllable delay processing is much higher than that of the baseband processing unit, so fractional compensation smaller than the chip time unit can be realized. If the required compensation accuracy is higher, the IF processing unit can also be implemented by filtering the digital signal through a digital filter. At this time, the accuracy of the delay compensation can reach a few hundredths of a chip cycle, and the delay processing can be controlled. The timing is more precise.

It can be seen from the above that with the time delay compensation implemented in step 21 and step 22, the baseband processing unit and the intermediate frequency processing unit on the entire path will be able to Accurately compensate for it, send data in advance, and synchronize the wireless frames arriving at the respective antenna ports. The synchronization reference finally refers to the time of the timing bus 10 in FIG. 1 .

In another embodiment in accordance with the principles of the invention, a delay compensation system is presented. Since the principle of the system is basically the same as the above-mentioned delay compensation method, only the technology specific to the system is illustrated and explained in this paper.

The delay compensation system in this embodiment includes a baseband processing unit, a data forwarding unit, an intermediate frequency processing unit, a radio frequency processing unit, and an antenna that sequentially process cell data. The difference between this embodiment and the prior art is that the baseband processing unit and the intermediate frequency processing unit respectively include a delay compensation circuit for compensating the pre-measured total delay of the data transmission path from the baseband processing unit to the antenna port and each cell. . Wherein, the delay compensation circuit in the baseband processing unit performs integer level compensation, and the delay compensation circuit in the intermediate frequency processing unit performs fractional level compensation.

When cell data passes through, the delay compensation circuit in the baseband processing unit performs integer-level delay compensation in units of chips, wherein the delay compensation circuit is composed of shift register groups; the delay compensation circuit in the intermediate frequency processing unit takes chips as units The unit performs fractional delay compensation, wherein the delay compensation circuit is composed of a shift register group, and its clock is higher than the chip rate. In another embodiment of the invention, the bank of shift registers is formed by digital filters. Therefore, the system achieves the purpose of synchronizing the wireless frames of each cell of the base station at the antenna port through the integer-level delay compensation of the baseband processing unit and the fractional-level delay compensation of the intermediate frequency processing unit.

Although the present invention has been illustrated and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein, and without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

1. A delay compensation method for mobile communication, characterized in that, comprising the following steps: Obtain the respective total delays of the data transmission paths of each cell from the baseband processing unit to the antenna port; The baseband processing unit and the intermediate frequency processing unit perform delay compensation on cell data transmitted through corresponding paths according to respective total delays of the cell data transmission paths. 2. The method for delay compensation used in mobile communication according to claim 1, wherein the baseband processing unit takes chips as a unit to carry out integer-level delay compensation to the cell data, and the intermediate frequency processing unit The unit performs fractional delay compensation on the cell data in units of chips. 3. The delay compensation method used in mobile communication according to claim 2, wherein the baseband processing unit performs integer-level delay compensation through a shift register group. 4. The delay compensation method for mobile communication according to claim 2 or 3, wherein the intermediate frequency processing unit performs fractional delay compensation through a shift register group, wherein the shift register group The rate at which the clock is higher than the chip. 5. The delay compensation method used in mobile communication according to claim 2 or 3, characterized in that the intermediate frequency processing unit performs fractional delay compensation through a digital filter. 6. A delay compensation system for mobile communications, comprising a baseband processing unit, a data forwarding unit, an intermediate frequency processing unit, a radio frequency processing unit and an antenna that are processed sequentially for cell data, characterized in that, The baseband processing unit and the intermediate frequency processing unit further include a delay compensation circuit for compensating the pre-measured respective total delays of data transmission paths of each cell from the baseband processing unit to the antenna port. 7. The delay compensation system according to claim 6, characterized in that, the delay compensation circuit in the baseband processing unit is used to take chips as a unit to carry out integer-level delay compensation; the delay in the intermediate frequency processing unit The compensation circuit is used to perform fractional delay compensation with a chip as a unit. 8. The delay compensation system according to claim 7, wherein the delay compensation circuit in the baseband processing unit is composed of a shift register group. 9. The delay compensation system according to claim 7 or 8, wherein the delay compensation circuit in the intermediate frequency processing unit is composed of a shift register group, wherein the clock of the shift register group is higher than the rate of chips . 10. The delay compensation system according to claim 7 or 8, characterized in that, the delay compensation circuit in the intermediate frequency processing unit is composed of a digital filter.

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