WO2012062080A1 - Method and system for realizating delay compensation in a distributed base station system - Google Patents

Abstract

A method for realizing delay compensation in a distributed base station system is disclosed in the present invention. The method includes that: a base-band unit determines a timing advance for sending downlink data, and sends the downlink data ahead of the whole network timing by the timing advance; and after receiving the downlink data, each radio frequency unit delays to send the downlink data to air interfaces to make the downlink data sent by each radio frequency unit simultaneously arrive at the air interfaces, and the duration of delay for sending the downlink data is the value that the timing advance T subtracts the delay duration TDL of downlink between the base-band unit and the radio frequency units. A system for realizing delay compensation in the distributed base station is provided in the present invention. A base-band unit in a distributed base station system is also disclosed in the present invention. With the present invention, a measurement and compensation method for achieving transmissions between the base-band unit and the radio frequency units, and processing delay by using Common Public Radio Interface (CPRI) is clarified.

Description

 Method and system for implementing delay compensation in distributed base station system

TECHNICAL FIELD The present invention relates to a distributed base station system, and more particularly to a method and system for realizing current delay compensation in a distributed base station system.

Background technique

The distributed base station architecture has become a trend in wireless communication systems. This architecture separates the Base Band Unit (BBU) and the Radio Radio Unit (RRU) and independently develops them, thus reducing development. Cost, increased networking flexibility. In the field of wireless communication using the Common Radio Radio Interface (CPRI) protocol standard, the baseband unit is called a Radio Equipment Control (REC), and the RRU is called a radio equipment. RE). In the distributed base station architecture, the BBU and the RRU are generally arranged in a remote manner by fiber optics or other cables, and the distance can be as long as several kilometers or even tens of kilometers. Because the transmission distance between the BBU and the RRU is different, or the RRU is different, the time that the BBU sends the signal to the air interface after the link transmission and the RRU processing is not synchronized, which causes the frame synchronization problem of the system networking. For the reverse link, after the RRU receives the air interface signal, the RRU process and the link transmission arrive at the BBU at different times, which increases the processing complexity of the BBU. The CPRI protocol defines the delay of each node based on the distributed base station system constructed by it, and gives a measurement method. In the CPRI protocol, the measurement of delay is based on Frame Timing. When the CPRI interface is used in different communication systems, the delay measurement is slightly different, especially for Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD) systems. The system's delay requirements are not the same. In addition, the CPRI protocol does not explicitly describe the delay compensation method. In general, various communication systems have the concept of a radio frame format regardless of the specific communication system. When combining the radio frame format and the CPRI protocol frame format, how to perform delay compensation becomes a problem to be solved. SUMMARY OF THE INVENTION The technical problem to be solved by the present invention is to provide a method and system for implementing delay compensation in a distributed base station system, which solves the problem of using a CPRI protocol standard in a Long Term Evolution (LTE) system. Compensation for link transmission and processing delays when baseband radio interface. In order to solve the above technical problem, the present invention provides a method for implementing delay compensation in a distributed base station system, the method comprising: determining, by a baseband unit, a time advance interval T for transmitting downlink data, and using the time advance interval Sending downlink data in advance of the whole network timing time; and after receiving the downlink data, each radio frequency unit delays transmitting downlink data to the air interface, so that downlink data sent by each radio unit reaches the air interface at the same time, and sends downlink data delay. The duration is the time advance interval T minus the value of the downlink delay duration Τι between the baseband unit and the radio unit. The method further includes: after the downlink data reaches the air interface synchronization, the radio unit sends the uplink data delay T1 to the baseband unit, and the baseband unit according to the uplink delay duration _TUL between the baseband unit and the radio unit. After the uplink air interface data sent by the radio unit is compensated, the uplink air interface data sent by each radio unit is obtained at the same time. The time advance interval T is related to the length of the optical fiber used to connect the baseband unit to the radio frequency unit and the processing delay of the radio frequency unit. The downlink delay duration 基ι between the baseband unit and the radio frequency unit refers to a delay period in which the baseband unit sends data to the radio frequency unit and then sends the radio frequency unit to the air interface. The value is:

T _DL (1) ₌ ^{T 14} ( ¹ )-Toffset( ₁ ) ₊ ^^ _{[N (k)] +} Ig _[TBdl(k) ― _TBul(k)] + _T2a(l)

2 2 _k=0 2 _k=0 Wherein, i represents a series index of the radio frequency unit to which the baseband unit is connected; T14 (1) refers to a loop delay of the baseband unit to the first-level radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The forwarding time of the radio interface downlink receiving data to the baseband radio interface connected to the next-level radio unit; TBul refers to the baseband connected to the next-level node in the cascade networking configuration mode The RF interface uplink receives data, and the data is sent to the baseband radio interface of the upper-level node for forwarding time; T2a refers to the duration that the radio unit receives data from the baseband radio interface downlink to send the data to the air interface. . among them,

 After the downlink data reaches the air interface synchronization, the radio unit sends the uplink data to the baseband unit without delay processing, that is, when the T1 value is 0, the base station unit uses the uplink delay time between the baseband unit and the radio unit. The TUL performs compensation processing on the uplink air interface data sent by each radio unit; the uplink delay duration TUL between the baseband unit and the radio unit is a delay that the radio unit receives the uplink data sent by the radio unit from the uplink to the baseband unit, Its value is:

T _UL (1) = TBu!(k)] + Ta3(i)

Wherein, i represents a series index of the radio frequency unit to which the baseband unit is connected; T14 (1) refers to a loop delay of the baseband unit to the first-level radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The forwarding time of the radio interface downlink receiving data to the baseband radio interface connected to the next-level radio unit; TBul refers to the baseband connected to the next-level node in the cascade networking configuration mode The radio interface receives data from the uplink, and sends the data to the baseband radio interface of the upper-level node. The Ta3 refers to the radio unit receiving data from the air interface to send the data. The duration of the uplink to the baseband radio interface. The delay time T1 when the radio unit delays the uplink air interface data is the maximum value of the uplink delay duration between the baseband unit and each radio unit minus the uplink delay duration between the baseband unit and the radio unit. Difference:

In order to solve the above technical problem, the present invention further provides a system for implementing delay compensation in a distributed base station system, the system comprising a baseband unit and a radio frequency unit, wherein the baseband unit is configured to: determine to transmit downlink data The time interval T is set, and the downlink data is sent in advance of the time interval T in advance of the whole network timing time; the radio frequency unit is configured to: after receiving the downlink data, delay sending the downlink data to the air interface, so that The downlink data sent by each radio unit arrives at the air interface at the same time, and the duration of the downlink data delay is the time interval T minus the value of the link downlink delay time T _D L between the baseband unit and the radio unit. The radio frequency unit is further configured to: after the downlink data reaches the air interface synchronization, send the uplink data delay T1 to the baseband unit; and the baseband unit is further configured to: according to the baseband unit and the radio frequency unit The uplink delay duration T _UL compensates the uplink air interface data sent by each radio unit, and simultaneously obtains the uplink air interface data sent by each radio unit. The downlink delay duration T _DL between the baseband unit and the radio frequency unit refers to a delay of the baseband unit transmitting data to the radio frequency unit and then sent by the radio frequency unit to the air interface, and the value is: T _DL (1) ₌ ^{T 14} ( ¹ )-Toffset( ₁ ) ₊ ^^ _{[N (k)] +} Ig _[TBdl(k) ― _TBul(k)] + _T2a(l) Wherein, i represents a series index of the radio frequency unit to which the baseband unit is connected; T14 (1) refers to a loop delay of the baseband unit to the first-level radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The forwarding time of the radio interface downlink receiving data to the baseband radio interface connected to the next-level radio unit; TBul refers to the baseband connected to the next-level node in the cascade networking configuration mode The RF interface uplink receives data, and the data is sent to the baseband radio interface of the upper-level node for forwarding time; T2a refers to the duration that the radio unit receives data from the baseband radio interface downlink to send the data to the air interface. . The baseband unit is configured to: after the downlink data reaches the air interface synchronization, the radio frequency unit does not perform delay processing on the received uplink data, and directly sends the data to the baseband unit, that is, when T1 takes a value of 0, the baseband unit and the radio frequency The uplink delay duration TUL between the units compensates the uplink air interface data sent by each radio unit; the uplink delay duration TUL between the baseband unit and the radio unit refers to the radio unit receiving the uplink data to the baseband unit for receiving The delay of the uplink data sent by the radio unit, which:

T _UL (1) = TBu!(k)] + Ta3(i)

Wherein, i represents a series index of the radio frequency unit to which the baseband unit is connected; T14 (1) refers to a loop delay of the baseband unit to the first-level radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The forwarding time of the radio interface downlink receiving data to the baseband radio interface connected to the next-level radio unit; TBul refers to the baseband connected to the next-level node in the cascade networking configuration mode The radio interface uplink receives data, and sends the data to the baseband of the upper node. The forwarding time of the radio interface; Ta3 refers to the length of time that the radio unit receives data from the air interface to send the data to the uplink of the baseband radio interface. The delay time T1 when delay processing the uplink air interface data is the maximum value of the uplink delay duration between the baseband unit and each radio unit minus the uplink delay duration between the baseband unit and the radio unit. Difference:

The baseband unit is configured to: perform compensation processing on uplink air interface data sent by each radio unit by using a maximum value of uplink delay duration between the baseband unit and each radio unit (Λ( )). In order to solve the above technical problem, the present invention also provides a baseband unit in a distributed base station system, where the baseband unit is configured to: determine a time advance interval T for transmitting downlink data, and advance by the time advance interval T The downlink data is sent in the whole network timing time, so that after receiving the downlink data, the radio frequency unit delays transmitting the downlink data to the air interface, so that the downlink data sent by each radio unit reaches the air interface at the same time, and the downlink data delay is sent. The duration is the time advance interval T minus the value of the link downlink delay duration T _D L between the baseband unit and the radio frequency unit. The baseband unit is further configured to: receive uplink data sent by the radio frequency unit to the baseband unit after the downlink data reaches the air interface synchronization, and delay the received uplink data by T1; and according to the baseband unit and the radio frequency unit The uplink delay time length T _UL compensates the uplink air interface data sent by each radio unit, and simultaneously obtains the uplink air interface data sent by each radio unit. The downlink delay duration T _DL between the baseband unit and the radio frequency unit refers to a delay period in which the baseband unit sends data to the radio frequency unit and then sent by the radio frequency unit to the air interface, and the value is: T _DL (i) ₌ ^{T 14} ( ¹ )-Toffset( ₁ ) ₊ ^^ _{[N (k)] +} Ig _[TBdl(k) ― _TBul(k)] + _T2a(l)

2 2 _k=0 2 _k=0 where i represents the series index of the radio unit connected to the baseband unit; T14 (1) refers to the loop delay of the baseband unit to the first stage radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The forwarding time of the radio interface downlink receiving data to the baseband radio interface connected to the next-level radio unit; TBul refers to the baseband connected to the next-level node in the cascade networking configuration mode The RF interface uplink receives data, and the data is sent to the baseband radio interface of the upper-level node for forwarding time; T2a refers to the duration that the radio unit receives data from the baseband radio interface downlink to send the data to the air interface. . The baseband unit is configured to: after the downlink data reaches the air interface synchronization, the radio frequency unit does not perform delay processing on the received uplink data, and directly sends the data to the baseband unit, that is, when T1 takes a value of 0, the baseband unit and the radio frequency The uplink delay duration TUL between the units compensates the uplink air interface data sent by each radio unit; the uplink delay duration TUL between the baseband unit and the radio unit refers to the radio unit receiving the uplink data to the baseband unit for receiving The delay of the uplink data sent by the radio unit, which: T _UL (1) = TBul(k)] + Ta3 _(l )

Wherein, i represents a series index of the radio frequency unit to which the baseband unit is connected; T14 (1) refers to a loop delay of the baseband unit to the first-level radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The delay time of the radio interface downlink receiving data to the baseband radio interface connected to the next-level radio unit; TBul means that in the cascade networking configuration mode, the radio unit is from the next-level node The baseband radio interface receives data from the uplink, and sends the data to the baseband radio interface of the upper-level node. The Ta3 refers to the radio unit receiving data from the air interface to send the data to the baseband radio interface uplink. The duration of the path; or the delay time T1 when delaying the uplink air interface data is the maximum value of the uplink delay between the baseband unit and each radio unit minus the uplink between the baseband unit and the radio unit The difference in delay time:

The baseband unit is configured to: perform compensation processing on uplink air interface data sent by each radio unit by using a maximum value Hf^)) of an uplink delay duration between the baseband unit and each radio unit. The present invention is applicable to an LTE system, and includes two modes of LTE-FDD and LTE-TDD. The present invention provides a scheme for measuring and compensating link transmission and processing delays when implementing a baseband radio frequency interface using the CPRI protocol standard under the LTE system. The invention clarifies the measurement and compensation method for the transmission and processing delay between the baseband unit and the radio frequency unit using the CPRI interface.

1 is a schematic diagram of a system for implementing delay compensation in a distributed base station system according to an embodiment of the present invention; FIG. 2 is a schematic diagram of a method for implementing delay compensation in a distributed base station system according to an embodiment of the present invention; In the embodiment, the baseband unit sends the downlink data ahead of the whole network timing time by using the time advance interval T. FIG. 4 is a schematic diagram of the baseband unit transmitting the downlink data in advance according to the embodiment of the present invention, and the data sent by the radio frequency unit cannot be aligned when being sent to the air interface. FIG. 5 is a schematic diagram of the baseband unit transmitting downlink data in advance according to an embodiment of the present invention, and the data is simultaneously applied to the air interface after the compensation processing by each radio unit; FIG. 6 is an uplink compensation method in the implementation of the present invention, and the baseband unit is uplinked. After delay compensation A schematic diagram of the starting point of the air interface data can be accurately found. FIG. 7 is a schematic diagram of the starting point of the air interface data after the baseband unit performs the uplink delay compensation in the uplink compensation mode 2.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that, in the case of no conflict, the features in the embodiments and the embodiments in the present application may be arbitrarily combined with each other.

1 shows a system for implementing delay compensation in a distributed base station system according to an embodiment of the present invention. The system for implementing delay compensation includes a baseband unit and a radio frequency unit. The baseband unit is configured to: determine a time advance interval T for transmitting downlink data, and send downlink data with the time advance interval T ahead of the entire network timing time. The radio frequency unit is configured to: after receiving the downlink data, delay sending downlink data to the air interface, so that downlink data sent by each radio unit reaches the air interface at the same time, and the duration of sending the downlink data delay is the time advance The interval T subtracts the value of the link downlink delay duration T _D L between the baseband unit and the radio frequency unit. The downlink delay duration T _DL between the baseband unit and the radio frequency unit refers to a delay of the baseband unit transmitting data to the radio frequency unit and then transmitting the radio frequency unit to the air interface. The specific values are:

T _DL (1) ₌ ^{T 14} ( ¹ )-Toffset( ₁ ) ₊ ^^ _{[N (k)] +} Ig _[TBdl(k) ― _TBul(k)] + _T2a(l)

2 2 _k=0 2 _k=0 where i represents the series index of the radio unit connected to the baseband unit; T14 (1) refers to the loop delay of the baseband unit to the first stage radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The forwarding time of the radio interface downlink receiving data to the baseband radio interface connected to the next-level radio unit; TBul refers to the baseband connected to the next-level node in the cascade networking configuration mode The radio interface receives data from the uplink, and sends the data to the baseband radio interface of the upper-level node. The T2a refers to the radio unit receiving data from the baseband radio interface downlink. The length of time that this data is sent to the air interface. The radio frequency unit is further configured to: after the downlink data reaches the air interface synchronization, delay the received uplink data by T1 and send the signal to the baseband unit. The baseband unit is further configured to: after performing uplink processing on the uplink air interface data sent by each radio unit according to an uplink delay duration TUL between the baseband unit and the radio frequency unit, obtain uplink air interface data sent by each radio unit. In the uplink compensation mode 1, the baseband unit is further configured to: after the downlink data reaches the air interface synchronization, the radio frequency unit sends the uplink data to the baseband unit without delay processing, that is, when T1 takes a value of 0, in the uplink air interface data length T _UL transmitted to each radio unit uplink between the baseband unit and RF unit delay compensation processing; uplink between the baseband unit and RF unit long delay T _UL refers to the radio frequency unit receives After the uplink data arrives, the baseband unit receives the delay of the uplink data sent by the radio unit, and the specific value is: [TBdl(k) - TBul(k)] + Ta3 (i)

Wherein, i represents a series index of the radio frequency unit to which the baseband unit is connected; T14 (1) refers to a loop delay of the baseband unit to the first-level radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The forwarding time of the radio interface downlink receiving data to the baseband radio interface connected to the next-level radio unit; TBul refers to the baseband connected to the next-level node in the cascade networking configuration mode The radio interface uplink receives data, and the data is sent to the baseband radio interface of the upper-level node for the forwarding duration; Ta3 refers to the duration that the radio unit receives data from the air interface to send the data to the baseband radio interface uplink. . In the uplink compensation mode 2, the radio frequency unit is further configured to: when the uplink air interface data is subjected to delay processing, the delay time T1 is when the uplink delay between the baseband unit and each radio unit is delayed.

The baseband unit is further configured to: perform compensation processing on uplink air interface data sent by each radio unit by using a maximum value of uplink delay duration between the baseband unit and each radio unit (Λ( )).

The delay measurement unit in the baseband unit and the radio frequency unit is configured to: measure each parameter value required, and the delay compensation unit in the baseband unit and the radio unit is used to perform compensation operation on the received or transmitted data. The delay calculation unit in the baseband unit is set to: calculate the time advance interval T and T _DL and TuLo

As shown in FIG. 2, the method for implementing delay compensation in a distributed base station system includes: determining, by a baseband unit, a time advance interval T for transmitting downlink data, and transmitting the downlink with the time advance interval T ahead of the entire network timing time. Data, after the radio frequency unit receives the downlink data, the duration of the data delay to the air interface is the time advance interval T minus the value of the downlink delay duration T _D L between the baseband unit and the radio unit. When the baseband unit sends downlink data in advance, the radio frame data is bound to the CPRI interface frame, that is,

The data carried by the first antenna carrier transmitted in the CPRI frame is the first sample data of the radio frame data. The frame timing of the CPRI interface is not affected by the delay compensation method. The BBU and the RRU perform delay compensation by adjusting the starting position of the service data. The whole network timing time refers to the whole network based on the Global Positioning System (GPS) or other synchronous systems, such as the Beidou system, which can extract the timing reference for the synchronization function of each unit in the whole network. As shown in FIG. 3, the baseband unit transmits downlink data at the time advance interval T ahead of the entire network timing time. The time advance interval T is mainly related to the length K of the optical fiber between the baseband unit and the radio frequency unit and the processing delay of the radio frequency unit. K is the system design, and all the radio frequency unit and the baseband unit under the baseband unit The maximum value of the distance between the fibers. For example, when the radio frequency unit managed by the baseband unit supports the time advance interval T within 10 km and the radio frequency unit managed by the baseband unit supports within 20 km, the corresponding time advance interval T has a large difference. In the specific calculation, the value of T can be taken as f

, where c is the speed of light. Time advance interval can also be down The transmission and processing delay indicators are related. The downlink transmission and processing delay indicators refer to the total transmission and processing delay indicators of the relevant nodes in the distributed base station system. The transmission and processing delays of the relevant nodes include the baseband radio interface processing of the baseband unit. Delay, link transmission delay, and RF unit processing delay. After the RF unit extracts the antenna data from the CPRI interface, it is processed by the intermediate frequency or RF circuit and sent to the air interface. In order to ensure the data synchronization sent by each radio unit to the air interface, the radio frequency unit needs to perform delay compensation processing on the downlink data. The delay compensation method in this embodiment is that the frame timing data of the CPRI interface is not compensated, and the antenna data extracted from the CPRI interface is subjected to delay processing, and each radio frequency unit performs delay processing of the corresponding delay compensation parameters on the antenna data. , to achieve the purpose of air interface data synchronization. The downlink delay duration T _DL between the baseband unit and the radio unit refers to the delay of the baseband unit transmitting data to the radio unit and then transmitting the radio unit to the air interface. The specific values are:

T _DL (1) ₌ ^{T 14} ( ¹ )-Toffset( ₁ ) ₊ ^^ _{[N (k)] +} Ig _[TBdl(k) ― _TBul(k)] + _T2a(l)

2 2 _k=0 2 _k=0 where i denotes the series index of the radio unit connected to the baseband unit, and the index of the nearest radio unit from the baseband unit is 1, and then increments by one. Τ14(1) refers to the loop delay of the baseband unit to the first-stage RF unit, and has the following calculation relationship with other parameters, T14(l) = T12(l) + Toffset(l) + T34(l), where 1) Both are related to the first-level radio unit, for example, T12(1) represents the downlink delay of the baseband unit to the first-stage radio unit; Toffset refers to the moment when the radio unit extracts the timing synchronization signal from the baseband radio interface downlink. The time interval to which the timing synchronization signal is used as the uplink timing synchronization signal; T _c refers to the duration of a basic frame in the CPRI link, which is a fixed value, and the size is (1/3840000) s; the value of N means that the radio unit will go up. The basic frame difference between the link receiving data and the uplink timing synchronization signal when sent to the baseband radio interface; TBdl means that in the cascade networking configuration mode, the radio unit is connected from the baseband radio interface downlink connected to the upper node. Receiving data to the forwarding time of the baseband radio interface connected to the next-level radio unit; TBul means that the radio unit is uplinked from the baseband radio interface connected to the next-level node in the cascade networking configuration mode Receiving data, the length and the forwarding data to the base band radio frequency interface on a node; refers T2 a radio unit from the base band RF interface receives downlink data and transmits the data to the length of time the air interface.

Typically, T _DL ( i ) can also take the following typical values: ^( = ⁿ⁴⁽¹⁾ " ^ffSet(i) ₊ ^a(i) The values of the parameters in the above equation are all defined parameters in the prior art. Each node specified in the CPRI protocol performs transmission or processing delay measurement. The baseband unit carries the radio frame data on the corresponding CPRI frame, and the baseband unit and the radio unit cooperate to complete the transmission of each node or the processing delay. The radio unit completes the T2a, Ta3, Toffset, TBdl, TBul specified in the CPRI protocol. And measuring the value of N, and transmitting the measurement result to the baseband unit through the CPRI interface. The baseband unit completes the measurement of the loop delay T14(1) of the baseband unit to the radio unit according to the uplink and downlink frame timing of the CPRI interface. It is shown that the baseband unit sends downlink data in advance, and assuming that the uplink and downlink delays of the radio units are different, when the radio unit transmits data to the air interface, the air interface data synchronization cannot be completed. As shown in FIG. 5, after the radio unit After the downlink delay compensation, the downlink data is synchronized in the air interface data.

The method further includes an uplink signal processing process: after the downlink data reaches the air interface synchronization, the radio unit sends the uplink data delay T1 to the baseband unit, and the baseband unit adjusts the uplink delay time between the baseband unit and the radio unit. After the TUL performs compensation processing on the uplink air interface data sent by each radio unit, the uplink air interface data sent by each radio unit is obtained at the same time. In the uplink compensation, one of the following uplink compensation modes may be used: Uplink compensation mode 1: The uplink air interface data received by the radio unit is carried on the CPRI interface and transmitted to the baseband unit. In order to ensure that the uplink data processing is correct, the baseband unit needs to find the starting point of the air interface radio frame data. In this embodiment, the baseband unit uses the system air interface timing as a reference, and performs delay compensation according to the calculated uplink delay measurement calculation result of each radio unit, so that the starting point of the air interface data can be accurately found, as shown in FIG. 6. Show. The compensated uplink data can be used for subsequent related baseband processing. After the downlink data reaches the air interface synchronization, the radio frequency unit receives the uplink data without any delay directly to the baseband unit, baseband unit to an uplink between the baseband unit and RF unit delay duration T _UL transmit the respective radio frequency unit Uplink air interface data for compensation processing; baseband The uplink delay duration TUL between the unit and the radio unit refers to the delay of the uplink data sent by the radio unit to the baseband unit frequency unit after receiving the uplink data, and the specific value is:

T _UL (1) = TBu!(k)] + Ta3(i)

Where i denotes the number index of the radio frequency unit to which the baseband unit is connected, and the index of the nearest radio frequency unit from the baseband unit is 1, and then increments by one. T14(l) refers to the loop delay of the baseband unit to the first-stage RF unit, and has the following calculation relationship with other parameters, T14(l)=T12(l)+Toffset(l)+T34(l), where 1) both indicate that it is related to the first-level radio unit, for example, T12(l) represents the downlink delay of the baseband unit to the first-stage radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the baseband radio interface downlink to the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of a basic frame in the CPRI link, which is a fixed value. The size is (1/3840000) s; the value of N refers to the basic frame difference of the uplink timing synchronization signal when the radio unit transmits the uplink received data to the baseband radio interface; TBdl refers to the cascading networking configuration mode. The radio unit receives the data from the downlink of the baseband radio interface connected to the upper-level node to the baseband radio interface connected to the next-level radio unit; TBul refers to the cascading network configuration mode. The radio unit receives data from the uplink of the baseband radio interface connected to the next-level node, and sends the data to the baseband radio interface of the upper-level node. The Ta3 refers to the radio unit receiving data from the air interface. The length of time this data is sent to the uplink of the baseband radio interface. Typically, T _UL (i) can also take the following typical values:

^( = ⁿ⁴⁽¹⁾ " ^ffSet(i) ^a3(i)

Uplink compensation mode 2: After receiving the uplink data, the RF unit performs uplink delay alignment compensation, that is, the delay time T1 of the delay time processing of the uplink air interface data by the radio unit is the uplink between the baseband unit and each radio unit. The maximum value of the path delay duration, T2, minus the difference in uplink delay between the baseband unit and the radio unit:

After this compensation, when the uplink data of each radio unit to which the baseband unit belongs is sent to the baseband unit, it arrives at the same time. Based on the system timing, the baseband unit compensates for the uplink air interface data sent by each radio unit by using the maximum value of the uplink delay duration between the baseband unit and each radio unit (Γ (>), ie, 2 The uplink air interface wireless data after the radio unit is synchronized, as shown in FIG.

The embodiment further provides a baseband unit in a distributed base station system, where the baseband unit is configured to: determine a time advance interval 用于 for transmitting downlink data, and send the time advance interval Τ ahead of the entire network timing time Downstream data, so that after receiving the downlink data, the radio frequency unit delays sending downlink data to the air interface, so that downlink data sent by each radio unit arrives at the air interface at the same time, and the duration of sending the downlink data delay is the time advance. The interval Τ subtracts the value of the link downlink delay duration T _D L between the baseband unit and the radio unit. The baseband unit is further configured to: receive uplink data sent by the radio frequency unit to the baseband unit after the downlink data reaches the air interface synchronization, and delay the received uplink data by T1; and according to the baseband unit and the radio frequency unit The uplink delay time length T _UL compensates the uplink air interface data sent by each radio unit, and simultaneously obtains the uplink air interface data sent by each radio unit. The downlink delay duration T _DL between the baseband unit and the radio frequency unit refers to a delay period in which the baseband unit sends data to the radio frequency unit and then sends the radio frequency unit to the air interface, and the value is:

T _DL (1) ₌ ^{T 14} ( ¹ )-Toffset( ₁ ) ₊ ^^ _{[N (k)] +} Ig _[TBdl(k) ― _TBul(k)] + _T2a(l)

2 2 _k=0 2 _k=0 where i represents the series index of the radio unit connected to the baseband unit; T14 (1) refers to the loop delay of the baseband unit to the first stage radio unit; _Ffset refers to the time when the radio unit extracts the timing synchronization signal from the baseband radio interface downlink to the timing synchronization signal as the uplink timing synchronization signal. The duration of the basic frame; T _c refers to the length of the basic frame of the public radio interface link; N value refers to the basic frame difference of the uplink timing synchronization signal when the radio unit transmits the uplink received data to the baseband radio interface; TBdl refers to In the cascading networking configuration mode, the radio unit receives the data from the downlink of the baseband radio interface connected to the upper-level node to the forwarding time of the data to the baseband radio interface connected to the next-level radio unit; TBul refers to In the cascading networking configuration mode, the radio unit receives data from the baseband radio interface uplink connected to the next-level node, and sends the data to the baseband radio interface of the upper-level node for forwarding. T2a refers to the radio unit. The length of time from when the baseband radio interface downlink receives data to when it is sent to the air interface. The baseband unit is configured to: after the downlink data reaches the air interface synchronization, the radio frequency unit does not perform delay processing on the received uplink data, and directly sends the data to the baseband unit, that is, when T1 takes a value of 0, the baseband unit and the radio frequency The uplink delay duration TUL between the units compensates the uplink air interface data sent by each radio unit; the uplink delay duration TUL between the baseband unit and the radio unit refers to the radio unit receiving the uplink data to the baseband unit for receiving The delay of the uplink data sent by the radio unit, which:

T _UL (1) = TBu!(k)] + Ta3(i)

Wherein, i represents a series index of the radio frequency unit to which the baseband unit is connected; T14 (1) refers to a loop delay of the baseband unit to the first-level radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The forwarding time of the radio interface downlink receiving data to the baseband radio interface connected to the next-level radio unit; TBul refers to the baseband connected to the next-level node in the cascade networking configuration mode The radio interface uplink receives data, and the data is sent to the baseband radio interface of the upper-level node for the forwarding duration; Ta3 refers to the duration that the radio unit receives data from the air interface to send the data to the baseband radio interface uplink. ; or The delay time T1 when delay processing the uplink air interface data is the maximum value of the uplink delay duration between the baseband unit and each radio unit minus the difference of the uplink delay between the baseband unit and the radio unit. :

 The baseband unit is configured to: perform compensation processing on uplink air interface data sent by each radio unit by using a maximum value of uplink delay between the baseband unit and each radio unit Λ^(Γ()).

The embodiment further provides a radio frequency unit in a distributed base station system, where the radio frequency unit is configured to: the receiving baseband unit advances the full time interval T after determining the time advance interval T for transmitting the downlink data. The downlink data sent by the network timing time; and after receiving the downlink data, delay sending the downlink data to the air interface, so that the downlink data sent by each radio unit reaches the air interface at the same time, and the duration of sending the downlink data delay is The time advance interval T minus the value of the link downlink delay duration Τι between the baseband unit and the radio unit. The radio frequency unit is further configured to: after the downlink data reaches the air interface synchronization, send the uplink data delay T1 to the baseband unit, so that the baseband unit is uplinked according to the baseband unit and the radio frequency unit. The link delay duration T _UL compensates the uplink air interface data sent by each radio unit, and simultaneously obtains the uplink air interface data sent by each radio unit. The downlink delay duration T _DL between the baseband unit and the radio frequency unit refers to a delay period in which the baseband unit sends data to the radio frequency unit and then sends the radio frequency unit to the air interface, and the value is:

T _DL (1) ₌ ^{T 14} ( ¹ )-Toffset( ₁ ) ₊ ^^ _{[N (k)] +} Ig _[TBdl(k) ― _TBul(k)] + _T2a(l)

2 2 _k=0 2 _k=0 where i represents the series index of the radio unit connected to the baseband unit; T14 (1) refers to the loop delay of the baseband unit to the first stage radio unit; _Ffset refers to the radio unit from the baseband radio interface downlink Taking the timing of the timing synchronization signal to the interval length of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; N value refers to the radio unit transmitting the uplink reception data to The base frame difference between the baseband radio interface and the uplink timing synchronization signal; TBdl means that in the cascade networking configuration mode, the radio unit receives data from the baseband radio interface downlink connected to the upper node to the data The forwarding time sent to the baseband radio interface connected to the next-level radio unit; TBul means that in the cascade networking configuration mode, the radio unit receives data from the baseband radio interface uplink connected to the next-level node, to The length of time that the data is sent to the baseband radio interface of the upper-level node; T2a refers to the length of time that the radio unit receives data from the baseband radio interface downlink to send the data to the air interface.

It is a matter of course that the invention may be embodied in various other forms and modifications without departing from the spirit and scope of the invention. One of ordinary skill in the art will appreciate that all or a portion of the above steps may be accomplished by a program instructing the associated hardware, such as a read-only memory, a magnetic disk, or an optical disk. Alternatively, all or part of the steps of the above embodiments may also be implemented using one or more integrated circuits. Correspondingly, each module/unit in the above embodiment may be implemented in the form of hardware or in the form of a software function module. The invention is not limited to any specific form of combination of hardware and software.

Industrial Applicability The present invention is applicable to an LTE system, and includes two modes of LTE-FDD and LTE-TDD. The present invention provides a scheme for measuring and compensating link transmission and processing delays when implementing a baseband radio interface using the CPRI protocol standard under the LTE standard. The present invention clarifies the measurement and compensation method for the transmission and processing delay between the baseband unit and the radio unit using the CPRI interface.

Claims

Claim

A method for implementing delay compensation in a distributed base station system, the method comprising: determining, by a baseband unit, a time advance interval T for transmitting downlink data, and transmitting the time advance interval T ahead of a full network timing time After receiving the downlink data, each radio frequency unit delays transmitting downlink data to the air interface, so that downlink data sent by each radio unit arrives at the air interface at the same time, and the duration of the downlink data delay is the time advance interval T. Subtract the value of the downlink delay duration Τι between the baseband unit and the radio unit.

2. The method according to claim 1, further comprising: after the downlink data reaches the air interface synchronization, the radio frequency unit sends the uplink data delay T1 to the baseband unit, and the baseband unit is configured according to the baseband unit and the radio frequency unit. The uplink uplink delay time T _UL compensates the uplink air interface data sent by each radio unit, and simultaneously obtains the uplink air interface data sent by each radio unit.

3. The method of claim 1, wherein the time advance interval T is related to a length of an optical fiber used to connect the baseband unit to the radio frequency unit and a processing delay of the radio frequency unit.

4. The method according to claim 1, wherein the downlink delay duration between the baseband unit and the radio frequency unit refers to a delay of the baseband unit transmitting data to the radio frequency unit and then transmitting the radio frequency element to the air interface process. Values are: T _DL (1) = - TBui + T2a(!)

Wherein, i represents a series index of the radio frequency unit to which the baseband unit is connected; T14 (1) refers to a loop delay of the baseband unit to the first-level radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the baseband radio interface downlink to the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the RF unit will be uplink The basic frame difference between the received data and the uplink timing synchronization signal when the data is transmitted to the baseband radio interface;

TBdl refers to the forwarding time of the radio frequency unit receiving data from the baseband radio interface downlink connected to the upper-level node to the baseband radio interface connected to the next-level radio unit in the cascade networking configuration mode; TBul refers to the forwarding time of the radio unit receiving data from the baseband radio interface uplink connected to the next-level node in the cascade networking configuration mode, and sending the data to the baseband radio interface of the upper-level node; T2a Refers to the length of time that the radio unit receives data from the baseband radio interface downlink to send the data to the air interface.

5. The method according to claim 2, wherein after the downlink data reaches the air interface synchronization, the radio frequency unit does not perform delay processing on the received uplink data and directly sends the data to the baseband unit, that is, when T1 takes a value of 0, the baseband unit The uplink delay duration TUL between the baseband unit and the radio unit compensates for the uplink air interface data sent by each radio unit; the uplink delay duration TUL between the baseband unit and the radio unit receives the uplink to baseband of the radio unit The delay of the unit receiving the uplink data sent by the radio unit, and the value is:

T _UL (1) = TBu!(k)] + Ta3(i)

Wherein, i represents a series index of the radio frequency unit to which the baseband unit is connected; T14 (1) refers to a loop delay of the baseband unit to the first-level radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The forwarding time of the radio interface downlink receiving data to the baseband radio interface connected to the next-level radio unit; TBul refers to the baseband connected to the next-level node in the cascade networking configuration mode The radio interface uplink receives data, and the data is sent to the baseband radio interface of the upper-level node for the forwarding duration; Ta3 refers to the duration that the radio unit receives data from the air interface to send the data to the baseband radio interface uplink. .

The method according to claim 2, wherein the delay time T1 of the delay time processing of the uplink air interface data by the radio frequency unit is a baseband single The maximum value of the uplink delay between the element and each radio unit minus the difference in the uplink delay between the base unit and the radio unit:

^ = MAX(T _UL {]))-T _UL {i)

A system for implementing delay compensation in a distributed base station system, the system comprising a baseband unit and a radio frequency unit, wherein the baseband unit is configured to: determine a time advance interval T for transmitting downlink data, and The time advance interval T is sent in advance to the whole network timing time to send downlink data. The radio frequency unit is configured to: after receiving the downlink data, delay sending the downlink data to the air interface, so that the downlink data sent by each radio unit arrives at the same time. The duration of the downlink data transmission delay is the time interval T minus the value of the link downlink delay duration T _D L between the baseband unit and the radio unit.

The system of claim 7, wherein the radio frequency unit is further configured to: after the downlink data reaches the air interface synchronization, send the uplink data delay T1 to the baseband unit; and the baseband unit further The method is as follows: After the uplink air interface data sent by each radio unit is compensated according to the uplink delay duration _TUL between the baseband unit and the radio unit, the uplink air interface data sent by each radio unit is obtained at the same time.

9. The system according to claim 7, wherein the downlink delay duration T _DL between the baseband unit and the radio frequency unit refers to a time when the baseband unit transmits data to the radio frequency unit and then sends the radio frequency unit to the air interface process. Delay, its value is:

T _DL (1) ₌ ^T14 ( ¹ )-Toffset( ₁ ) ₊ ^^ _{[N(k)] +} Ig _[TBdl(k) ― _TBul(k)] + _T2a(l)

2 2 _k=0 2 _k=0 where i represents the series index of the radio frequency unit to which the baseband unit is connected; T14 (1) refers to the baseband unit Loop delay to the first stage RF unit; T. _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The forwarding time of the radio interface downlink receiving data to the baseband radio interface connected to the next-level radio unit; TBul refers to the baseband connected to the next-level node in the cascade networking configuration mode The RF interface uplink receives data, and the data is sent to the baseband radio interface of the upper-level node for forwarding time; T2a refers to the duration that the radio unit receives data from the baseband radio interface downlink to send the data to the air interface. .

10. The system according to claim 8, wherein the baseband unit is configured to: after the downlink data reaches the air interface synchronization, the radio frequency unit sends the uplink data without delay processing to the baseband unit, that is, T1. When the value is 0, the uplink air interface data sent by each radio unit is compensated by the uplink delay duration TUL between the baseband unit and the radio unit; the uplink delay duration TUL between the baseband unit and the radio unit is The delay in receiving the uplink data from the radio unit to the baseband unit and receiving the uplink data sent by the radio unit, where:

T _UL (1) = TBu!(k)] + Ta3(i)

Wherein, i represents a series index of the radio frequency unit to which the baseband unit is connected; T14 (1) refers to a loop delay of the baseband unit to the first-level radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The forwarding time of the radio interface downlink receiving data to the baseband radio interface connected to the next-level radio unit; TBul refers to the baseband connected to the next-level node in the cascade networking configuration mode The radio interface receives data from the uplink, and sends the data to the baseband radio interface of the upper-level node. The Ta3 refers to the radio unit receiving data from the air interface to send the data. The duration of the uplink to the baseband radio interface.

1 1. The system according to claim 8, wherein the delay time T1 when delay processing the uplink air interface data is the maximum value of the uplink delay duration between the baseband unit and each radio unit minus the baseband unit. The difference in uplink delay between this RF unit:

The baseband unit is configured to: perform compensation processing on uplink air interface data sent by each radio unit by using a maximum value of uplink delay duration between the baseband unit and each radio unit (Λ( )).

12 . A baseband unit in a distributed base station system, where the baseband unit is configured to: determine a time advance interval T for transmitting downlink data, and send downlink data by using the time advance interval T ahead of a full network timing time, After the radio frequency unit receives the downlink data, the downlink data is delayed to be sent to the air interface, so that the downlink data sent by each radio unit reaches the air interface at the same time, and the time delay of sending the downlink data delay is the time advance interval T minus The value of the link downlink delay time T _D L between the baseband unit and the radio unit.

The baseband unit according to claim 12, wherein the baseband unit is further configured to: receive, after the downlink data reaches the air interface synchronization, the uplink radio frequency unit sends a delay to the received uplink data T1 and then sends the uplink to the baseband unit. Data; and, according to the uplink delay duration _TUL between the baseband unit and the radio unit, the uplink air interface data sent by each radio unit is compensated, and the uplink air interface data sent by each radio unit is obtained at the same time.

The baseband unit according to claim 12, wherein the downlink delay duration T _DL between the baseband unit and the radio frequency unit refers to a process in which the baseband unit transmits data to the radio frequency unit and then is sent by the radio frequency unit to the air interface. Delay, its value is: T _DL (i) ₌ ^{T 14} ( ¹ )-Toffset( ₁ ) ₊ ^^ _{[N (k)] +} Ig _[TBdl(k) ― _TBul(k)] + _T2a(l)

2 2 _k=0 2 _k=0 where i represents the series index of the radio unit connected to the baseband unit; T14 (1) refers to the loop delay of the baseband unit to the first stage radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The forwarding time of the radio interface downlink receiving data to the baseband radio interface connected to the next-level radio unit; TBul refers to the baseband connected to the next-level node in the cascade networking configuration mode The RF interface uplink receives data, and the data is sent to the baseband radio interface of the upper-level node for forwarding time; T2a refers to the duration that the radio unit receives data from the baseband radio interface downlink to send the data to the air interface. .

The baseband unit according to claim 13, wherein the baseband unit is configured to: after the downlink data reaches the air interface synchronization, the radio frequency unit sends the uplink data to the baseband unit without delay processing. When the value of T1 is 0, the uplink air interface data sent by each radio unit is compensated by the uplink delay duration TUL between the baseband unit and the radio unit; the uplink delay duration TUL between the baseband unit and the radio unit Refers to the delay that the radio unit receives the uplink data to the base station unit and receives the uplink data sent by the radio unit. It: T _UL (1) = TBul(k)] + Ta3 _(l )

Wherein, i represents a series index of the radio frequency unit to which the baseband unit is connected; T14 (1) refers to a loop delay of the baseband unit to the first-level radio unit; _Ffset refers to the interval between the time when the radio frequency unit extracts the timing synchronization signal from the downlink of the baseband radio interface interface and the timing of the timing synchronization signal as the uplink timing synchronization signal; T _c refers to the duration of the basic frame of the public radio interface link; Refers to the basic frame difference of the uplink timing synchronization signal when the RF unit sends the uplink received data to the baseband radio interface; TBdl refers to the baseband connected to the upper-level node in the cascaded network configuration mode. The radio interface downlink receives data to send the data to the baseband radio frequency connection connected to the next-level radio unit. The forwarding time of the port; TBul means that in the cascade networking configuration mode, the radio unit receives data from the baseband radio interface uplink connected to the next-level node, and sends the data to the baseband radio interface with the upper-level node. The length of the forwarding time; the length of time T1 when the radio unit receives data from the air interface to send the data to the uplink of the baseband radio interface; or the delay time T1 of the delay time of the uplink air interface data is the baseband unit and each radio frequency The maximum value of the uplink delay between units minus the difference in uplink delay between the base unit and this radio unit:

The baseband unit is configured to: perform compensation processing on uplink air interface data sent by each radio unit by using a maximum value of uplink delay duration between the baseband unit and each radio unit (Λ( )).