CN105792236B

CN105792236B - Time delay obtaining method and device, baseband unit and communication system

Info

Publication number: CN105792236B
Application number: CN201410829277.5A
Authority: CN
Inventors: 张德刚; 杨涛
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2014-12-26
Filing date: 2014-12-26
Publication date: 2021-01-26
Anticipated expiration: 2034-12-26
Also published as: CN105792236A; WO2016101603A1

Abstract

The invention discloses a time delay acquisition method, a time delay acquisition device, a baseband unit and a communication system, wherein the method comprises the following steps: calculating forward time delay of each radio remote unit RRU in a bidirectional link of the ring network; calculating the reverse time delay of each RRU in the two-way link of the ring network according to the forward time delay; sending the reverse time delay to the corresponding RRU; and after the ring network bidirectional link is switched, acquiring the reverse time delay reported by each RRU. Through the implementation of the invention, before the ring network switching, the reverse time delay corresponding to each RRU is obtained according to the forward time delay of each stage of RRU in the two-way link of the ring network and is sent to the corresponding RRU, thus, after the ring network switching, each stage of RRU can report the previously obtained reverse time delay to the BBU, the time required by the BBU for detecting/obtaining the time delay after the link switching is saved, the switching can be rapidly completed, and the switching time of each stage of RRU in the ring network mode is greatly shortened.

Description

Time delay obtaining method and device, baseband unit and communication system

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a method and an apparatus for acquiring a time delay in a ring network bidirectional link established based on a CPRI protocol, a baseband unit, and a communication system.

Background

In a communication system established by using a Common Public Radio Interface (CPRI) protocol, for example, in a ring network bidirectional link formed by sequentially connecting a Baseband Unit (BBU) and a plurality of RRUs (Radio Remote units) in a CPRI protocol networking, the requirement for the switching time of each level of RRUs is higher and higher, and in the prior art, each level of RRUs performs delay acquisition of each level of RRUs after the link switching is completed according to a flow specified by the CPRI protocol, and the acquisition has a delay, which results in a slow ring network switching speed.

Therefore, how to provide a delay obtaining technique capable of quickly completing the delay technique after ring network switching is a technical problem to be solved urgently by those skilled in the art.

Disclosure of Invention

The invention provides a time delay obtaining method, a time delay obtaining device, a baseband unit and a communication system, which can improve the time delay obtaining speed of each stage of RRU after ring network switching, and further can quickly calculate reverse optical fiber time delay after switching.

The invention provides a time delay obtaining method of a ring network bidirectional link, which comprises the following steps: acquiring forward time delay of each radio remote unit RRU in a bidirectional link of a ring network; acquiring reverse time delay of each RRU in the ring network bidirectional link according to the forward time delay; sending the reverse time delay to the corresponding RRU; and after the ring network bidirectional link is switched, acquiring the reverse time delay reported by each RRU.

Further, before obtaining the reverse delay of each RRU in the ring network bidirectional link according to the forward delay, the above embodiment further includes: determining a virtual breakpoint of the looped network bidirectional link according to the RRU stage number in the looped network bidirectional link, and acquiring reverse time delay of the virtual breakpoint; the step of obtaining the reverse time delay of each RRU in the ring network bidirectional link according to the forward time delay specifically comprises: and acquiring the reverse time delay of each RRU in the ring network bidirectional link according to the reverse time delay and the forward time delay of the virtual breakpoint.

Further, the step of determining the virtual breakpoint of the ring network bidirectional link according to the RRU stage number in the ring network bidirectional link in the above embodiment includes: when the RRU series is even, the half series number of RRUs connected with the BBU main optical port are inverted to the BBU main optical port, the half series number of RRUs connected with the BBU slave optical port are inverted to the BBU slave optical port, when the RRU series is odd, the half series number connected with the BBU main optical port is inverted to the BBU main optical port in the whole number, and the half series number connected with the BBU slave optical port is inverted to the BBU slave optical port in the whole number; and determining an optical fiber connecting the RRU which is inverted to the BBU main optical port and the RRU which is inverted to the BBU slave optical port as a virtual breakpoint.

Further, the step of obtaining the reverse time delay of each RRU in the ring network bidirectional link according to the reverse time delay and the forward time delay of the virtual breakpoint in the above embodiment includes: and sequentially acquiring the reverse time delay of each RRU according to the connection sequence from the RRU connected with the virtual breakpoint to the RRU connected with the BBU.

Further, the step of obtaining the reverse time delay of each RRU in the ring network bidirectional link according to the forward time delay in the above embodiment includes: determining the forward fiber time delay between the current-stage RRU and the upper-stage RRU or BBU in the forward time delay as the reverse fiber time delay between the current-stage RRU and the upper-stage RRU or BBU in the reverse time delay; determining a frame offset Toffset (forward direction) of a downlink input signal and an uplink output signal in the RRU time delay in the forward time delay as a frame offset Toffset (reverse direction) of the downlink input signal and the uplink output signal in the RRU time delay in the reverse time delay; determining the input and output delay TBdelayDL (forward direction) of a downlink signal in the RRU time delay in the forward direction delay as the input and output delay TBdelayDL (reverse direction) of the downlink signal in the RRU time delay in the reverse direction delay; in the reverse delay, the frame header deviation N (reverse) of the input and output of the uplink signal in the RRU delay is as follows: n (reverse) of the RRU is TBdelayDL (reverse) + of the RRU and the downlink fiber delay (reverse) + Toffset (reverse) + of the RRU and the uplink fiber delay (reverse) + of the RRU, Toffset (reverse) ÷ 3.84 of the RRU; after the RRU is switched on the ring network bidirectional link, reporting the N value as: rounding up the N (reverse direction) of the RRU at the current stage; the input and output delay TBdelayUL (reverse) of the uplink signal within the RRU delay in the reverse delay is: TBdelayUL [ [ N (reverse) rounding up of N (reverse) for this stage RRU-N (reverse) ÷ 1000 × 3.84 for this stage RRU; after the RRU is switched over in the ring network bidirectional link, the reported TBdelayUL value is: TBdelayUL (reverse) for this stage of RRU.

The invention provides a time delay obtaining device of a ring network bidirectional link, which comprises the following components in one embodiment: the processor is used for acquiring the forward time delay of each RRU in the two-way link of the ring network; acquiring reverse time delay of each RRU in the ring network bidirectional link according to the forward time delay; and the communication module is used for sending the reverse time delay to the corresponding RRUs and acquiring the reverse time delay reported by each RRU after the ring network bidirectional link is switched.

Further, the processor in the above embodiment is further configured to determine a virtual breakpoint of the ring network bidirectional link according to the number of RRUs in the ring network bidirectional link before obtaining the reverse delay of each RRU in the ring network bidirectional link according to the forward delay, and obtain the reverse delay of the virtual breakpoint; and acquiring the reverse time delay of each RRU in the ring network bidirectional link according to the reverse time delay and the forward time delay of the virtual breakpoint.

Further, the processor in the above embodiment is specifically configured to, when the number of RRUs is an even number, reverse the half-number of RRUs connected to the BBU main optical port, reverse the half-number of RRUs connected to the BBU slave optical port, when the number of RRUs is an odd number, reverse the half-number of RRUs connected to the BBU main optical port by an integer number upward, and reverse the half-number of RRUs connected to the BBU slave optical port by an integer number downward to the BBU slave optical port; and determining an optical fiber connecting the RRU which is inverted to the BBU main optical port and the RRU which is inverted to the BBU slave optical port as a virtual breakpoint.

Further, the processor in the foregoing embodiment is specifically configured to sequentially acquire the reverse time delays of the RRUs according to a connection sequence from the RRU connected to the virtual breakpoint to the RRU connected to the BBU.

Further, the processor in the foregoing embodiment is specifically configured to: determining the forward optical fiber time delay in the forward time delay as the reverse optical fiber time delay in the reverse time delay; determining a frame offset Toffset (forward direction) of a downlink input signal and an uplink output signal in the RRU time delay in the forward time delay as a frame offset Toffset (reverse direction) of the downlink input signal and the uplink output signal in the RRU time delay in the reverse time delay; determining the input and output delay TBdelayDL (forward direction) of a downlink signal in the RRU time delay in the forward direction delay as the input and output delay TBdelayDL (reverse direction) of the downlink signal in the RRU time delay in the reverse direction delay; in the reverse delay, the frame header deviation N (reverse) of the input and output of the uplink signal in the RRU delay is as follows: n (reverse) of the RRU is TBdelayDL (reverse) + of the RRU and the downlink fiber delay (reverse) + Toffset (reverse) + of the RRU and the uplink fiber delay (reverse) + of the RRU, Toffset (reverse) ÷ 3.84 of the RRU; the input and output delay TBdelayUL (reverse) of the uplink signal within the RRU delay in the reverse delay is: TBdelayUL [ [ N (reverse) of this stage RRU, rounded up value of N (reverse) ÷ 1000 × 3.84 of this stage RRU.

The invention provides a baseband unit, which comprises the time delay acquisition device provided by the invention.

The invention provides a communication system which comprises a baseband unit and a plurality of stages of RRUs, wherein the plurality of stages of RRUs are sequentially connected through CPRI interfaces and form a looped network bidirectional link with the baseband unit.

The invention has the beneficial effects that:

according to the scheme provided by the invention, before the ring network is switched, the reverse time delay corresponding to each RRU is obtained according to the forward time delay of each stage of RRU in the bidirectional link of the ring network and is sent to the corresponding RRU, so that after the ring network is switched, each stage of RRU can report the previously obtained reverse time delay, particularly the N value and the TBdelayUL value which can be changed after the link is switched to the BBU, the time required by the BBU for detecting/obtaining the N value and the TBdelayUL value after the link is switched is saved, the switching can be rapidly completed, the switching time of each stage of RRU in the ring network mode is greatly shortened, and the switching performance of each stage of RRU in the ring network mode is also greatly improved.

Drawings

Fig. 1 is a flowchart of a delay obtaining method according to a first embodiment of the present invention;

fig. 2 is a schematic diagram of a delay obtaining apparatus according to a second embodiment of the present invention;

fig. 3 is a block diagram of a communication system according to a third embodiment of the present invention;

fig. 4 is a frame header timing diagram after switching of the communication system in the third embodiment of the present invention;

fig. 5 is a block diagram of a communication system in a fourth embodiment of the present invention;

fig. 6 is a flowchart of a delay obtaining method according to a fourth embodiment of the present invention.

Detailed Description

The invention will now be further explained by means of embodiments in conjunction with the accompanying drawings.

The forward time delay refers to the time delay of each stage of RRU when the ring network bidirectional link is not switched, and the reverse time delay refers to the time delay of each stage of RRU after the ring network bidirectional link is switched; the method and the device finish the acquisition of the reverse time delay before the switching, so that if the ring network is switched, each stage of RRU can quickly acquire the time delay (reverse time delay), various adjustments are performed after the switching is finished, and the switching time is shortened.

The first embodiment:

fig. 1 is a flowchart of a time delay obtaining method according to a first embodiment of the present invention, and as can be seen from fig. 1, in this embodiment, the time delay obtaining method according to the present invention includes the following steps:

s101: calculating forward time delay of each radio remote unit RRU in a bidirectional link of the ring network;

s102: calculating the reverse time delay of each RRU in the two-way link of the ring network according to the forward time delay;

s103: sending the reverse time delay to the corresponding RRU;

s104: after the ring network bidirectional link is switched, reverse time delay reported by each RRU is obtained; therefore, the BBU can quickly complete the reverse fiber time delay of each stage of RRU after the link switching is completed.

In some embodiments, before calculating the reverse delay of each RRU in the ring network bidirectional link according to the forward delay in the embodiment shown in fig. 1, the method further includes: determining a virtual breakpoint of the looped network bidirectional link according to the RRU stage number in the looped network bidirectional link, and calculating the reverse time delay of the virtual breakpoint; the step of calculating the reverse time delay of each RRU in the ring network bidirectional link according to the forward time delay specifically comprises: and calculating the reverse time delay of each RRU in the two-way link of the ring network according to the reverse time delay and the forward time delay of the virtual breakpoint.

In some embodiments, the step of determining the virtual breakpoint of the ring network bidirectional link according to the RRU stage number in the ring network bidirectional link in the above embodiments includes: when the RRU series is even, the half series number of RRUs connected with the BBU main optical port are inverted to the BBU main optical port, the half series number of RRUs connected with the BBU slave optical port are inverted to the BBU slave optical port, when the RRU series is odd, the half series number connected with the BBU main optical port is inverted to the BBU main optical port in the whole number, and the half series number connected with the BBU slave optical port is inverted to the BBU slave optical port in the whole number; and determining an optical fiber connecting the RRU which is inverted to the BBU main optical port and the RRU which is inverted to the BBU slave optical port as a virtual breakpoint.

In some embodiments, the step of calculating the reverse delay of each RRU in the ring network bidirectional link according to the reverse delay and the forward delay of the virtual breakpoint in the above embodiments includes: and sequentially calculating the reverse time delay of each RRU according to the connection sequence from the RRU connected with the virtual breakpoint to the RRU connected with the BBU.

In some embodiments, the step of calculating the reverse delay of each RRU in the ring network bidirectional link according to the forward delay in the above embodiments includes: determining the forward fiber time delay between the current-stage RRU and the upper-stage RRU or BBU in the forward time delay as the reverse fiber time delay between the current-stage RRU and the upper-stage RRU or BBU in the reverse time delay; determining a frame offset Toffset (forward direction) of a downlink input signal and an uplink output signal in the RRU time delay in the forward time delay as a frame offset Toffset (reverse direction) of the downlink input signal and the uplink output signal in the RRU time delay in the reverse time delay; determining the input and output delay TBdelayDL (forward direction) of a downlink signal in the RRU time delay in the forward direction delay as the input and output delay TBdelayDL (reverse direction) of the downlink signal in the RRU time delay in the reverse direction delay; in the reverse delay, the frame header deviation N (reverse) of the input and output of the uplink signal in the RRU delay is as follows: n (reverse) of the RRU is TBdelayDL (reverse) + of the RRU and downlink fiber delay (reverse) + Toffset (reverse) + of the RRU and uplink fiber delay (reverse) of the RRU, Toffset (reverse) ÷ 3.84 of the RRU; after the RRU is switched on the ring network bidirectional link, reporting the N value as: rounding up the N (reverse direction) of the RRU at the current stage; the input and output delay TBdelayUL (reverse) of the uplink signal within the RRU delay in the reverse delay is: TBdelayUL [ [ N (reverse) rounding up of N (reverse) for this stage RRU-N (reverse) ÷ 1000 × 3.84 for this stage RRU; after the RRU is switched over in the ring network bidirectional link, the reported TBdelayUL value is: TBdelayUL (reverse) for this stage of RRU.

Second embodiment:

fig. 2 is a schematic diagram of a latency obtaining apparatus according to a second embodiment of the present invention, and as can be seen from fig. 2, in this embodiment, the latency obtaining apparatus 2 according to the present invention includes a processor 21 and a communication module 22, wherein,

the processor 21 is configured to obtain a forward time delay of each remote radio unit RRU in the ring network bidirectional link; acquiring reverse time delay of each RRU in the ring network bidirectional link according to the forward time delay;

and the communication module 22 is configured to send the reverse time delay to the corresponding RRUs, and obtain the reverse time delay reported by each RRU after the ring network bidirectional link is switched.

In some embodiments, the processor 21 in the embodiment shown in fig. 2 is further configured to determine a virtual breakpoint of the ring network bidirectional link according to the number of RRUs in the ring network bidirectional link before calculating the reverse delay of each RRU in the ring network bidirectional link according to the forward delay, and calculate the reverse delay of the virtual breakpoint; and calculating the reverse time delay of each RRU in the two-way link of the ring network according to the reverse time delay and the forward time delay of the virtual breakpoint.

In some embodiments, the processor 21 in the embodiment shown in fig. 2 is specifically configured to, when the number of RRUs is an even number, reverse the half-number of RRUs connected to the BBU main optical port, reverse the half-number of RRUs connected to the BBU slave optical port, when the number of RRUs is an odd number, reverse the half-number of RRUs connected to the BBU main optical port in an upward integer manner, and reverse the half-number of RRUs connected to the BBU slave optical port in a downward integer manner to the BBU slave optical port in an downward integer manner; and determining an optical fiber connecting the RRU which is inverted to the BBU main optical port and the RRU which is inverted to the BBU slave optical port as a virtual breakpoint.

In some embodiments, the processor 21 in the embodiment shown in fig. 2 is specifically configured to sequentially calculate the reverse time delay of each RRU according to a connection sequence from the RRU connected to the virtual breakpoint to the RRU connected to the BBU.

In some embodiments, the processor 21 in the embodiment shown in fig. 2 is specifically configured to: determining the forward optical fiber time delay in the forward time delay as the reverse optical fiber time delay in the reverse time delay; determining a frame offset Toffset (forward direction) of a downlink input signal and an uplink output signal in the RRU time delay in the forward time delay as a frame offset Toffset (reverse direction) of the downlink input signal and the uplink output signal in the RRU time delay in the reverse time delay; determining the input and output delay TBdelayDL (forward direction) of a downlink signal in the RRU time delay in the forward direction delay as the input and output delay TBdelayDL (reverse direction) of the downlink signal in the RRU time delay in the reverse direction delay; in the reverse delay, the frame header deviation N (reverse) of the input and output of the uplink signal in the RRU delay is as follows: : n (reverse) of the RRU is TBdelayDL (reverse) + of the RRU and the downlink fiber delay (reverse) + Toffset (reverse) + of the RRU and the uplink fiber delay (reverse) + of the RRU, Toffset (reverse) ÷ 3.84 of the RRU; the input and output delay TBdelayUL (reverse) of the uplink signal within the RRU delay in the reverse delay is: TBdelayUL [ [ N (reverse) of this stage RRU, rounded up value of N (reverse) ÷ 1000 × 3.84 of this stage RRU.

The third embodiment:

the embodiment mainly explains the acquisition mechanism provided by the invention, and the specific details are as follows:

the meaning of the parameters related to the present application will be described with reference to fig. 3 (a):

t12 is the fiber delay of the downlink, T34 is the fiber delay of the uplink, T14 is the frame frequency offset of the uplink and downlink connection signals, Toffset is the frame offset of the downlink input signal RB2 and the uplink output signal RB3 in the RRU, TBdelayDL is the delay of the downlink signal RB2 and RB1 in the RRU, TBdelayDL is the delay of the uplink signal RB4 and RB3 in the RRU, N is the deviation of the frame header position at the uplink signal RB3 with respect to the frame header position of RB4, and the unit of N is the basic frame (1/3.84 Mhz);

with reference to fig. 3 (B), through the forward fiber delay measurement process, it is possible to obtain the values of the TBdelayDL (RRU1 forward), TBdelayDL (RRU2 forward), T12 forward, Toffset (RRU2 forward), T34 forward, TBdelayDL (RRU1 forward), TBdelayDL (RRU2 forward), N (RRU1 forward), N (RRU2 forward), and other delay measurement parameters

When switching occurs, the reverse delay measurement parameters of each stage of RRUs are shown by dashed arrows in fig. 3 (B); the timing diagram of the reverse delay frame header after the RRU switching is shown in fig. 4:

the following equations can be obtained by combining fig. 3 and fig. 4:

n (RRU2 reverse) + Toffset (RRU2 reverse) ═ TBdelayDL (RRU2 reverse) + T12 (reverse) + Toffset (RRU1 reverse) + T34 (reverse) + TBdelayDL (RRU2 reverse); further, it can be deduced that:

n (RRU2 reverse) -TBdelayUL (RRU2 reverse) ═ TBdelayDL (RRU2 reverse) + T12 (reverse) + Toffset (RRU1 reverse) + T34 (reverse) -Toffset (RRU2 reverse);

since T12 reverse direction is T12 forward direction, T34 reverse direction is T34 forward direction, and T12 forward direction and T34 forward direction are known values, Toffset (RRU1 reverse direction), TBdelayDL (RRU2 reverse direction), Toffset (RRU2 reverse direction) are fixed values, the same as their corresponding forward values, and have been obtained;

and N (RRU2 reverse) is an integer multiple of 1/3.84Mhz, TBdelayUL (RRU2) reverse is a value less than 1/3.84 Mhz; then it can be inferred that:

n (RRU2 reverse) ═ TBdelayDL (RRU2 reverse) + T12 (reverse) + Toffset (RRU1 reverse) + T34 (reverse) -Toffset (RRU2 reverse) ÷ 3.84 × 1000; since the unit of the actually reported N value is 3.84Mhz, the actually reported N value is: rounded up values for N (RRU2 reverse);

TBdelayUL (RRU2 reverse) — N (RRU2 reverse) — an rounded up value-N (RRU2 reverse) ÷ 1000 × 3.84; unit: ns.

The fourth embodiment:

the present invention is further explained with reference to a specific application example, in this embodiment, it is assumed that the BBUR and 5 RRUs form a ring network bidirectional link, as shown in fig. 5, the definitions of various parameters are the same as those in the third embodiment, and the virtual break point is an optical fiber after the RRU No. 3 and the RRU No. 4; as can be seen from fig. 6, in this embodiment, the time delay obtaining method provided by the present invention includes the following steps:

s601: the BBU initiates an optical fiber time delay measurement flow on the main optical interface, and calculates the optical fiber time delays of the RRU1, the RRU2 and the RRU3 on the preferred optical interface; the method specifically comprises the following steps:

calculate the fiber length for RRU 1:

t12 (RRU forward No. 1) ═ T34 (RRU forward No. 1) ═ T14(BBU optical port 0) -Toffset (RRU forward No. 1)/2;

t12(1) ═ T12 (RRU forward No. 1), T34(1) ═ T34 (RRU forward No. 1)

Calculate the fiber length for RRU 2:

t12 (RRU forward No. 2) ═ T14(BBU optical port 0) + N (RRU forward No. 1) -Toffset (RRU forward No. 2) + TBdelayDL (RRU forward No. 1) -TBdelayDL (RRU forward No. 1)/2;

t34 (RRU forward No. 2) ═ T14(BBU optical port 0) + N (RRU forward No. 1) -Toffset (RRU forward No. 2) -TBdelayDL (RRU forward No. 1) + TBdelayDL (RRU forward No. 1)/2;

t12(2) ═ T12 (RRU forward No. 2) -T12 (RRU forward No. 1) -TBdelayDL (RRU forward No. 1);

t34(2) ═ T34 (RRU forward No. 2) -T34 (RRU forward No. 1) - [ N (RRU forward No. 1) -TBdelayUL (RRU forward No. 1) ];

calculate the fiber length for RRU 3:

t12 (RRU forward No. 3) ═ T14(BBU optical port 0) + N (RRU forward No. 1) + N (RRU forward No. 2) -Toffset (RRU forward No. 3) + TBdelayDL (RRU forward No. 1) + TBdelayDL (RRU forward No. 2) -TBdelayDL (RRU forward No. 1) -TBdelayDL (RRU forward No. 2)/2;

t34 (RRU forward No. 3) ═ T14(BBU optical port 0) + N (RRU forward No. 1) + N (RRU forward No. 2) -Toffset (RRU forward No. 3) -TBdelayDL (RRU forward No. 1) -TBdelayDL (RRU forward No. 2) + TBdelayDL (RRU forward No. 1) + TBdelayDL (RRU forward No. 2)/2;

t12(3) ═ T12 (RRU forward No. 3) -T12 (RRU forward No. 2) -TBdelayDL (RRU forward No. 2);

t34(3) ═ T34 (RRU forward No. 3) -T34 (RRU forward No. 2) - [ N (RRU forward No. 2) -TBdelayUL (RRU forward No. 2) ];

s602: the BBU initiates an optical fiber time delay measurement process on the slave optical interface, and calculates the optical fiber time delays of the RRU5 and the RRU4 on the preferred optical interface; the method specifically comprises the following steps:

calculate the fiber length for RRU 5:

t12 (RRU forward No. 5) ═ T34 (RRU forward No. 5) ═ T14(BBU optical port 1) -Toffset (RRU forward No. 5)/2;

t12(6) ═ T12 (RRU forward No. 5), T34(6) ═ T34 (RRU forward No. 5);

calculate the fiber length for RRU 4:

t12 (RRU forward No. 4) ═ T14(BBU optical port 1) + N (RRU forward No. 5) -Toffset (RRU forward No. 4) + TBdelayDL (RRU forward No. 5) -TBdelayDL (RRU forward No. 5) ]/2;

t34 (RRU forward No. 4) ═ T14(BBU optical port 1) + N (RRU forward No. 5) -Toffset (RRU forward No. 4) -TbdelayDL (RRU forward No. 5) + TbdelayDL (RRU forward No. 5)/2;

t12(5) ═ T12 (RRU forward No. 4) -T12 (RRU forward No. 5) -TbdelayDL (RRU forward No. 5);

t34(5) ═ T34 (RRU forward No. 4) -T34 (RRU forward No. 5) - [ N (RRU forward No. 5) -TBdelayUL (RRU forward No. 5) ];

s603: the BBU initiates optical fiber time delay measurement of virtual break point on the main optical port; the method specifically comprises the following steps:

shorting RRU 4; a lower optical interface of the RRU4 receives a CPRI frame header and loops back to a sending CPRI frame header, and a time delay value set by the loop is set as a Toffset initial default value;

s604: the BBU initiates a reverse optical fiber time delay measurement flow on the main optical port, and calculates reverse optical fiber time delays of the RRU1, the RRU2 and the RRU 3; the method specifically comprises the following steps:

querying time delay parameters of RRU4, namely Toffset (RRU forward direction No. 4), TbdelayDL (RRU forward direction No. 4), TBdelayUL (RRU forward direction No. 4) and N (RRU forward direction No. 4);

computing the redundant fiber T12 (4):

t12(4) ═ T34(4) ═ N (RRU forward No. 3) + Toffset (RRU forward No. 3) -TBdelayUL (RRU forward No. 3) -TbdelayDL (RRU forward No. 3) -Toffset (RRU reverse No. 4) ]/2

Calculating the reverse time delay of the RRU 2:

n (RRU reverse No. 2) ═ TBdelayDL (RRU reverse No. 3) + T12(3) + Toffset (RRU reverse No. 2) + T34(3) -Toffset (RRU reverse No. 2) ÷ 3.84 × 1000; the BBU sends N (RRU No. 2 in reverse direction) to RRU2, RRU2 rounds the ring network, and reports the N (RRU No. 2 in reverse direction) to BBU in unit of 1/3.84 Mhz;

TBdelayUL (RRU reverse No. 2) ═ N (RRU reverse No. 2)/3.84- [ TBdelayDL (RRU reverse No. 3) + T12(3) + Toffset (RRU reverse No. 2) + T34(3) -Toffset (RRU reverse No. 2) ] ÷ 1000 × 3.84, unit: ns;

calculating the reverse time delay of the RRU 1:

n (RRU reverse No. 1) ═ TBdelayDL (RRU reverse No. 2) + T12(2) + Toffset (RRU reverse No. 1) + T34(2) -Toffset (RRU reverse No. 1) ÷ 3.84 × 1000; the BBU sends N (RRU No. 1 in reverse direction) to RRU1, RRU1 rounds the ring network, and reports the N (RRU No. 1 in reverse direction) to BBU in 1/3.84 Mhz;

TBdelayUL (RRU reverse No. 1) ═ N (RRU reverse No. 1)/3.84- [ TBdelayDL (RRU reverse No. 2) + T12(2) + Toffset (RRU reverse No. 1) + T34(2) -Toffset (RRU reverse No. 1) ] ÷ 1000 × 3.84, unit: ns;

s605: the BBU initiates a reverse optical fiber time delay measurement flow on the slave optical port, and calculates reverse optical fiber time delays of the RRU5 and the RRU 4; the method specifically comprises the following steps:

querying time delay parameters of RRU3, namely Toffset (RRU forward direction No. 3), TbdelayDL (RRU forward direction No. 3), TBdelayUL (RRU forward direction No. 3) and N (RRU forward direction No. 3);

calculating a redundant optical fiber:

the redundant fiber results that have been calculated before can be used directly, or can be recalculated:

t12(4) ═ T34(4) ═ N (RRU forward No. 4) + Toffset (RRU forward No. 4) -TBdelayUL (RRU forward No. 4) -TbdelayDL (RRU forward No. 4) -Toffset (RRU reverse No. 3) ]/2;

calculating the reverse time delay of the RRU 4:

n (RRU reverse No. 4) ═ TBdelayDL (RRU reverse No. 3) + T12(4) + Toffset (RRU reverse No. 4) + T34(4) -Toffset (RRU reverse No. 3) ÷ 3.84 × 1000; the BBU sends N (RRU No. 4 reverse) to RRU4, RRU4 rounds the ring network, and reports the N (RRU No. 4 reverse) to BBU with unit of 1/3.84 Mhz;

TBdelayUL (RRU reverse No. 4) ═ N (RRU reverse No. 4)/3.84- [ TBdelayDL (RRU reverse No. 3) + T12(4) + Toffset (RRU reverse No. 4) + T34(4) -Toffset (RRU reverse No. 3) ] div 1000 × 3.84, unit: ns;

calculating the reverse time delay of the RRU 5:

n (RRU reverse No. 5) ═ TBdelayDL (RRU reverse No. 4) + T12(5) + Toffset (RRU reverse No. 5) + T34(5) -Toffset (RRU reverse No. 4) ÷ 3.84 × 1000; the BBU sends N (RRU No. 5 in reverse direction) to RRU5, and RRU5 rounds the ring network and reports the rounded N (RRU No. 5 in reverse direction) to the BBU; the unit is 1/3.84 Mhz;

TBdelayUL (RRU reverse No. 5) ═ N (RRU reverse No. 5)/3.84- [ TBdelayDL (RRU reverse No. 4) + T12(5) + Toffset (RRU reverse No. 5) + T34(5) -Toffset (RRU reverse No. 4) ] div 1000 × 3.84, unit: ns;

s606: the BBU sends reverse time delay to the corresponding RRU;

therefore, after the link is switched, the RRU can quickly send the corresponding reverse delay parameter to the BBU, and the BBU can complete subsequent frame header adjustment and other operations, so that the switching can be quickly completed.

In summary, the implementation of the present invention has at least the following advantages:

before the ring network is switched, the reverse time delay corresponding to each RRU is obtained according to the forward time delay of each stage of RRU in the bidirectional link of the ring network and is sent to the corresponding RRU, so that after the ring network is switched, each stage of RRU can report the previously obtained reverse time delay, especially the N value and the TBdelayUL value which can be changed after the link is switched to the BBU, the time required by the BBU for detecting/obtaining the N value and the TBdelayUL value after the link is switched is saved, the switching can be quickly completed, the switching time of each stage of RRU in the ring network mode is greatly shortened, and the switching performance of each stage of RRU in the ring network mode is also greatly improved.

The above embodiments are only examples of the present invention, and are not intended to limit the present invention in any way, and any simple modification, equivalent change, combination or modification made by the technical essence of the present invention to the above embodiments still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for obtaining time delay of a ring network bidirectional link is characterized by comprising the following steps:

calculating the forward time delay of each RRU in the two-way link of the ring network;

calculating the reverse time delay of each RRU in the ring network bidirectional link according to the forward time delay;

sending the reverse time delay to a corresponding RRU;

after the ring network bidirectional link is switched, the reverse time delay reported by each RRU is obtained;

the step of calculating the reverse time delay of each RRU in the ring network bidirectional link according to the forward time delay includes:

determining the forward fiber time delay between the RRU of the current stage and the RRU of the upper stage or the BBU in the forward time delay as the reverse fiber time delay between the RRU of the current stage and the RRU of the upper stage or the BBU in the reverse time delay; determining a frame offset Toffset (forward direction) of a downlink input signal and an uplink output signal in the RRU time delay in the forward direction time delay as a frame offset Toffset (reverse direction) of a downlink input signal and an uplink output signal in the RRU time delay in the reverse direction time delay; determining the input and output delay TBdelayDL (forward direction) of the downlink signal in the RRU time delay in the forward direction delay as the input and output delay TBdelayDL (reverse direction) of the downlink signal in the RRU time delay in the reverse direction delay;

frame header deviation N (reverse) of input and output of an uplink signal in RRU time delay in the reverse time delay is as follows: n (reverse) of the RRU is TBdelayDL (reverse) + of the RRU and the downlink fiber delay (reverse) + Toffset (reverse) + of the RRU and the uplink fiber delay (reverse) + of the RRU, Toffset (reverse) ÷ 3.84 of the RRU; after the RRU is switched on the ring network bidirectional link, reporting an N value as: the N (reverse direction) of the RRU at the current stage is rounded up;

the input and output delay TBdelayUL (reverse) of the uplink signal in the RRU delay in the reverse delay is as follows:

TBdelayUL [ [ N (reverse) rounding up of N (reverse) for this stage RRU-N (reverse) ÷ 1000 × 3.84 for this stage RRU; after the RRU switches between the two-way links of the ring network, the reported TBdelayUL value is: the TBdelayUL (reverse) of the RRU of this stage.

2. The delay obtaining method of claim 1, wherein before calculating the reverse delay of each RRU in the ring network bidirectional link according to the forward delay, the method further comprises: determining a virtual breakpoint of the looped network bidirectional link according to the RRU stage number in the looped network bidirectional link, and calculating the reverse time delay of the virtual breakpoint; the step of calculating the reverse time delay of each RRU in the ring network bidirectional link according to the forward time delay specifically comprises: and calculating the reverse time delay of each RRU in the ring network bidirectional link according to the reverse time delay of the virtual breakpoint and the forward time delay.

3. The delay obtaining method of claim 2, wherein the step of determining the virtual breakpoint of the ring network bidirectional link according to the RRU stage number in the ring network bidirectional link comprises: when the RRU series is even, the half series number of RRUs connected with a BBU main optical port are inverted to the BBU main optical port, the half series number of RRUs connected with a BBU slave optical port are inverted to the BBU slave optical port, when the RRU series is odd, the half series number of RRUs connected with the BBU main optical port is inverted to the BBU main optical port in an upward integer manner, and the half series number of RRUs connected with the BBU slave optical port is inverted to the BBU slave optical port in a downward integer manner; and determining an optical fiber connecting the RRU which is inverted to the BBU main optical port and the RRU which is inverted to the BBU slave optical port as a virtual breakpoint.

4. The method for obtaining delay of claim 2, wherein the step of calculating the reverse delay of each RRU in the ring network bidirectional link according to the reverse delay of the virtual breakpoint and the forward delay comprises: and sequentially calculating the reverse time delay of each RRU according to the connection sequence from the RRU connected with the virtual breakpoint to the RRU connected with the BBU.

5. A time delay obtaining device for a two-way link of a ring network is characterized by comprising:

the processor is used for calculating the forward time delay of each RRU in the ring network bidirectional link; calculating the reverse time delay of each RRU in the ring network bidirectional link according to the forward time delay;

the communication module is used for sending the reverse time delay to the corresponding RRUs and acquiring the reverse time delay reported by each RRU after the ring network bidirectional link is switched;

the processor is specifically configured to:

determining the forward optical fiber time delay in the forward time delay as the reverse optical fiber time delay in the reverse time delay; determining a frame offset Toffset (forward direction) of a downlink input signal and an uplink output signal in the RRU time delay in the forward direction time delay as a frame offset Toffset (reverse direction) of a downlink input signal and an uplink output signal in the RRU time delay in the reverse direction time delay; determining the input and output delay TBdelayDL (forward direction) of the downlink signal in the RRU time delay in the forward direction delay as the input and output delay TBdelayDL (reverse direction) of the downlink signal in the RRU time delay in the reverse direction delay;

frame header deviation N (reverse) of input and output of an uplink signal in RRU time delay in the reverse time delay is as follows: n (reverse) of the RRU is TBdelayDL (reverse) + of the RRU and the downlink fiber delay (reverse) + Toffset (reverse) + of the RRU and the uplink fiber delay (reverse) + of the RRU, Toffset (reverse) ÷ 3.84 of the RRU;

TBdelayUL [ [ N (reverse) of this stage RRU, rounded up value of N (reverse) ÷ 1000 × 3.84 of this stage RRU.

6. The apparatus of claim 5, wherein the processor is further configured to determine a virtual breakpoint of the ring network bidirectional link according to the number of RRUs in the ring network bidirectional link before calculating the reverse delay of each RRU in the ring network bidirectional link according to the forward delay, and calculate the reverse delay of the virtual breakpoint; and calculating the reverse time delay of each RRU in the ring network bidirectional link according to the reverse time delay of the virtual breakpoint and the forward time delay.

7. The delay obtaining apparatus of claim 6, wherein the processor is specifically configured to, when the number of RRUs is an even number, reverse a half of the number of RRUs connected to a BBU main optical port to the BBU main optical port, reverse a half of the number of RRUs connected to a BBU slave optical port to the BBU slave optical port, when the number of RRUs is an odd number, reverse the entire number of RRUs from the half of the number of RRUs connected to the BBU main optical port, and reverse the entire number of RRUs from the half of the number of RRUs connected to the BBU slave optical port; and determining an optical fiber connecting the RRU which is inverted to the BBU main optical port and the RRU which is inverted to the BBU slave optical port as a virtual breakpoint.

8. The apparatus of claim 6, wherein the processor is specifically configured to sequentially calculate the reverse time delays of the RRUs according to a connection order from the RRU connected to the virtual breakpoint to the RRU connected to the BBU.

9. A baseband unit comprising a delay acquisition apparatus according to any one of claims 5 to 8.

10. A communication system, comprising the baseband unit of claim 9, and multiple levels of RRUs, wherein the multiple levels of RRUs are sequentially connected through a CPRI interface, and form a ring network bidirectional link with the baseband unit.