CN101442798B - Ascending/descending synchronous communication method for radio base station control node and cascade far-end node thereof - Google Patents

Abstract

The invention relates to mobile communication field, especially relating to method for synchronous communication that control node of a base station cascading with multiple remote node under TDD. Transmission time of service data of every level RRU is configurable at BBU side; the BBU separately notifies the configured transmission time to RRU of every level and transmits the service data of RRU of every level at set transmission time; RRU of every level receives service data of RRU of present level in set time advance corresponding to Uu port. RRu cached data quantity is controlled in a reasonable range, cache space is not needed to add, thereby cost is reduced; distance is prolonged for RRU, the invention is more conveniently used.

Description

Wireless base-station control node and cascade far-end node ascending/descending synchronous communication method thereof

Technical field

The present invention relates to moving communicating field, refer to the method for a plurality of distant-end node synchronous communications of Control Node cascade of a base station of time division duplex (TDD) standard especially.

Background technology

The structure of typical cellular communication system as shown in Figure 1, subscriber equipment (UE) communicates in propagation of eating dishes without rice or wine and system side equipment by wireless signal.System side equipment comprises base station (Node B), radio network controller (RNC) and equipment of the core network (CN), and wherein RNC and Node B form RNS (RNS).

Node B can be divided into digital processing part or Base-Band Processing and partly call in the following text with Radio frequency Processing Unit, RF Processing Unit and call RRU in the following text.By conventional method, Node B designs for integral type, and promptly BBU and RRU are arranged in same rack, and perhaps both are positioned at same place, and perhaps both distances are very short.And in new design, the design that Node B more and more adopts BBU and RRU to be separated adopts optical fiber or cable to communicate between the two.Therefore a BBU often can carry out Base-Band Processing at a plurality of RRU, has the situation of a plurality of RRU by a link cascade, the schematic diagram of cascade as shown in Figure 2, the interface between BBU and the RRU is referred to as the Ir interface.

Need transmit traffic data between BBU and the RRU, business datum is a base band data, comprises component and quadrature component (IQ) in the same way.As shown in Figure 3, radio frames or wireless sub-frame are made up of M chip (chip), and for example radio frames comprises the IQ data of 12800 chips, i.e. M=12800 concerning TD-SCDMA.During real work, a frame M chip differs and has established a capital valid data.On a bar link of a plurality of RRU cascades, the IQ data of a chip of all RRU are formed a data set, are referred to as Group.The link data frame also can have other definition mode, and being divided into some super group as a link data frame is Super-Group, and a Super-Group is divided into some Group again, but other definition mode does not change applicability of the present invention.One frame data comprise M Group, number Group respectively ⁰～Group ^M-1In present base station system, as BBU and the RRU of TD-SCDMA, a Group comprises the IQ data of the same chip of each RRU of cascade, and the chip of each RRU numbering is identical in the just same Group.Such as: Group ⁰Comprise RRU ⁽⁰⁾Chip ⁰IQ data, RRU ⁽¹⁾Chip ⁰The IQ data ... RRU ^(N-1)Chip ⁰The IQ data.This way can cause a problem in the TDD base station, if each RRU distance of cascade is distant, promptly data propagation delay time between each RRU is long, and then the closer to the RRU of BBU, it needs the data in buffer amount just big more.

As shown in Figure 4, illustrate with two descending situations of RRU of cascade, but this does not hinder the general applicability of conclusion to the more RRU of cascade.For the TDD base station, as the TD-SCDMA base station, the radio frames eating dishes without rice or wine of each base station is the requirement alignment, and this can realize synchronously by GPS.This requires the initial moment t of each RRU in the radio frames of eating dishes without rice or wine _AirChip ⁰Data send out eating dishes without rice or wine.If the shortest time that the RRU deal with data needs is T _Min, chip then ⁰Data must be at moment t _Min=t _Air-T _MinArrive corresponding RRU before.

One frame data send from BBU, because RRU ⁽⁰⁾More close BBU, then Group ⁰The data (chip that comprises each RRU ⁰Data) at first arrive RRU at moment t1 ⁽⁰⁾, t1 is with respect to t constantly _MinThe time interval in advance is T2.At moment t2Group ⁰Arrive RRU ⁽¹⁾, t2 must be at t _MinBefore.T2 is with respect to t constantly _MinThe time interval in advance is T4, and obviously, RRU (1) needs the data cached chip data that are no more than transmission in the time interval T4.And for RRU ⁽⁰⁾, because Group ⁰Compare RRU the time of advent ⁽¹⁾Shifted to an earlier date T3, so RRU ⁽⁰⁾Than RRU ⁽¹⁾The data of transmission in many cache-times interval T 3.Work as RRU ⁽¹⁾Distance R RU ⁽⁰⁾Far away more, promptly T3 is big more, then RRU ⁽⁰⁾Need data in buffer also many more.For the up similar problem that also exists.So just cause two consequences: 1) RRU need increase spatial cache, thereby causes cost to increase; When 2) spatial cache can not increase again, just limited the distance that RRU zooms out.

During the RRU cascade, for certain RRU, from the BBU RRU of subordinate that is referred to as this RRU far away, from the near higher level RRU that is referred to as this RRU of BBU.

Summary of the invention

Technical problem to be solved by this invention provides a kind of reduction distant-end node spatial cache, does not limit the wireless base-station control node and the cascade far-end node ascending/descending synchronous communication method thereof of the distance that distant-end node zooms out.

For solving the problems of the technologies described above, the invention provides the down-going synchronous communication means of a kind of wireless base-station control node and distant-end node, described Control Node is that some grades of distant-end nodes of BBU cascade are RRU, it is characterized in that: the delivery time of the business datum of every grade of RRU on the Ir mouth is configurable in the BBU side, described BBU notifies described RRU at different levels respectively with the described delivery time of described configuration, described BBU sends the business datum of described RRU at different levels at the delivery time of its setting, RRU at different levels receive the business datum of RRU at the corresponding levels in the Timing Advance of the relative Uu mouth of setting, described BBU measures the data transmission delay of RRU at different levels respectively before the described BBU configuration delivery time, is respectively: T ⁽⁰⁾, T ⁽¹⁾T ^(N-1)Corresponding RRU ⁽⁰⁾, RRU ⁽⁰⁾～RRU ^(N-1), the business datum of described RRU at different levels is made up of continuous RRU Frame, and a RRU Frame is that chip forms by M chip, numbers chip respectively ⁰～chip ^M-1, chip is by a pair of or some IQ is formed; Article one, Ir interface link data are made up of continuous link data frame, and a link data frame is that Group forms by M data set, is numbered Group respectively ⁰～Group ^M-1, a Group comprises the data of a chip of RRU at different levels, described RRU business datums at different levels at the delivery time of BBU side by described RRU chip at different levels ⁰Place Group numbering and Group ⁰Delivery time determine.

The chip of described RRU at different levels ⁰The corresponding different Group of difference, described BBU determines RRU ^(N-1)Chip ⁰Corresponding Group numbering, RRU ^(N-1)Chip ⁰Corresponding Group ⁰, RRU ⁽ⁿ⁾Chip ⁰Corresponding Group ^K, described ^KValue is time interval T ^(N-1)-T ⁽ⁿ⁾The Group quantity that interior BBU can transmit to the RRU interface; The K value rounds, and is described ⁽ⁿ⁾ Value 0～N-2; Described BBU is with described RRU chip at different levels ⁰Corresponding Group numbering is by the described RRU at different levels of Operation and Maintenance message informing.

Described BBU is according to described RRU chip at different levels ⁰Corresponding Group numbering is formed continuous Frame to described Group and is sent described Frame at the delivery time that described BBU sets.Described Group ⁰Delivery time before the initial moment of Uu mouth radio frames, described Group ⁰Delivery time and the time difference between the initial moment of Uu mouth radio frames be T ^(N-1With the Timing Advance sum.The maximum time lead that described Timing Advance can be supported less than described RRU spatial caches at different levels greater than the time of described RRU at different levels processing downlink data frame itself.

Described RRU receives described Operation and Maintenance message, knows the chip of this RRU ⁰Corresponding Group numbering ^K

Described RRU receives the Frame of BBU, determines Group by the method for frame synchronization ⁰The position, described RRU is from Group ⁰Begin counting, thereby can determine Group ^KThe position, and then can determine this RRU chip ⁰Original position, described RRU is according to chip ⁰Original position obtain the Frame of this RRU.

Adopt wireless base-station control node of the present invention and cascade far-end node ascending/descending synchronous communication method thereof, RRU data in buffer amount is controlled within the reasonable range, need not to increase spatial cache, has reduced cost; Also can increase simultaneously the distance that zooms out of RRU, more convenient in the practical application.

Description of drawings

Fig. 1 is the structure chart of general cellular communication system;

Fig. 2 is the schematic diagram of BBU by a plurality of RRU of link cascade;

Fig. 3 is the schematic diagram of the composition of a frame or subframe business datum;

Fig. 4 is the sequential chart of BBU and cascaded RRUs transfer of data in the present method;

Fig. 5 is the sequential chart of BBU of the present invention and cascaded RRUs transfer of data.

Embodiment

Technical spirit of the present invention is described in detail as follows by embodiment below in conjunction with accompanying drawing:

As shown in Figure 5: for descending, the chip of each RRU that same Group comprises numbering is no longer identical, such as Group ⁰Comprise RRU ⁽ⁿ⁾(the chip of n=0～N-2) ^M-KAnd RRU ^(N-1)Chip ⁰, chip herein ^M-KBe RRU ⁽ⁿ⁾The data of previous frame, the K value that different n is corresponding different.RRU just ^(N-1)Chip ⁰Be from Group ⁰Beginning, and RRU ⁽ⁿ⁾Chip ⁰Be from Group ^KBegin, i.e. Group ^KComprise RRU ^(N-1)Chip ⁰And RRU ⁽ⁿ⁾Chip ^K

For descending, the concrete steps that BBU one side is implemented are as follows:

The first step, BBU and RRU both sides arrange data quantity transmitted in the T4 time interval, can receive for the RRU spatial cache, can comprise the data of 1～8 chip such as T4;

In second step, BBU measures the time delay of each RRU respectively, is expressed as T ⁽⁰⁾, T ⁽¹⁾T ^(N-1), the corresponding RRU of difference ⁽⁰⁾, RRU ⁽⁰⁾～RRU ^(N-1)

In the 3rd step, BBU determines that it sends Group ⁰Time t ₀, t0=t _Air-(T ^(N-1)+ T4+T _Min);

In the 4th step, BBU determines RRU ^(N-1)Chip ⁰Corresponding Group numbering: RRU ^(N-1) Chip 0 from Group ⁰Beginning;

In the 4th step, BBU determines RRU ⁽ⁿ⁾(the chip of n=0～N-2) ⁰Corresponding Group numbering ^K, the K=time interval (T ^(N-1)-T ⁽ⁿ⁾) the Group quantity that can transmit on the interior BBU-RRU interface, K round numbers herein;

In the 5th step, BBU is each RRU chip ⁰Corresponding Group numbering is by each RRU of Operation and Maintenance message informing;

In the 6th step, BBU is according to each RRU chip ⁰Corresponding Group numbering is formed continuous Frame to data;

In the 7th step, BBU is always at the moment of each frame t ₀Transmission is with Group ⁰Initial Frame.

To RRU ⁽ⁿ⁾, it does not need from Group ⁰Begin data cached, and only need be from Group ^KThe data of this RRU of this frame of beginning buffer memory, this is because Group ^KComprise RRU ⁽ⁿ⁾First chip of this frame is chip ⁰Data.As long as can guarantee Group ^KAt moment t _MinArrive RRU before ⁽ⁿ⁾, system just can operate as normal.This way can reduce RRU ⁽ⁿ⁾The metadata cache space that needs.

For descending, the implementation step of RRU one side is:

The first step, RRU cooperates BBU to finish the latency measurement of BBU to RRU;

In second step, RRU receives the message of BBU, knows the chip of this RRU ⁰Corresponding Group numbering ^K

In the 3rd step, RRU receives the Frame of BBU, at first determines Group ⁰The position.Concrete definite method is the synchronous method of achieve frame;

In the 4th step, RRU is from Group ⁰Begin counting, thereby can determine Group ^KThe position, and then can determine this RRU chip ⁰Original position.

In the 5th step, RRU is according to chip ⁰Original position obtain the Frame of this RRU.

For up, the concrete steps of enforcement are:

The first step is established RRU ⁽ⁿ⁾(the up chip of n=0～N-1) ⁰With respect to Group ⁰Side-play amount be Offset (n:n), RRU ⁽ⁿ⁾, upstream data is sent to RRU ^(n-1)(n 〉=1 o'clock);

Second step, RRU ^(n-1)(n 〉=1 o'clock) receives RRU ⁽ⁿ⁾Upstream data, transmit behind the framing again, again the Group behind the framing ⁰With respect to receiving data Group ⁰A side-play amount is arranged, and establishing this side-play amount is Offset (n:n-1);

The 3rd step, RRU ^(n-2)(n 〉=2 o'clock) receive RRU ^(n-1)Upstream data, transmit behind the framing again, again the Group behind the framing ⁰With respect to receiving data Group ⁰A side-play amount is arranged, and establishing this side-play amount is Offset (n-1:n-2);

In the 4th step, repeated for the 3rd step, up to RRU ⁽⁰⁾Carry out respective handling, obtain Offset (n:1);

In the 5th step, each RRU of cascade reports separately Offset value to BBU;

In the 6th step, BBU calculates RRU (n) chip ⁰Receive data Group with respect to BBU ⁰Side-play amount, method is as follows:

$\mathrm{Offset}\left(n\right)=\underset{i=0}{\overset{n}{\mathrm{\Σ}}}\mathrm{Offset}(n:i)$

In the 7th step, BBU obtains the up IQ Frame of RRU (n) according to the position of determining RRU (n) chip0.

Claims (7)

1. the down-going synchronous communication means of wireless base-station control node and distant-end node, described Control Node is that some grades of distant-end nodes of baseband processing unit BBU cascade are far-end RF module RRU, it is characterized in that: the delivery time of the business datum of every grade of RRU on the Ir mouth is configurable in the BBU side, described BBU measures the data transmission delay of RRU at different levels respectively before the described BBU configuration delivery time, is respectively: T ⁽⁰⁾, T ⁽¹⁾... T ^(N-1)Corresponding RRU ⁽⁰⁾, RRU ⁽¹⁾～RRU ^(N-1), N represents N RRU, and the business datum of described RRU at different levels is made up of continuous RRU Frame, and a RRU Frame is that chip forms by M chip, numbers chip respectively ⁰～chip ^M-1, chip is by a pair of or some quadrature component IQ is formed; Article one, Ir interface link data are made up of continuous link data frame, and a link data frame is that Group forms by M data set, is numbered Group respectively ⁰～Group ^M-1, a Group comprises the data of a chip of RRU at different levels, described RRU business datums at different levels at the delivery time of BBU side by described RRU chip at different levels ⁰Place Group numbering and Group ⁰Delivery time determine, described BBU notifies described RRU at different levels respectively with the described delivery time of described configuration, described BBU sends the business datum of described RRU at different levels at the delivery time of its setting, and RRU at different levels receive the business datum of RRU at the corresponding levels in the Timing Advance of the relative Uu mouth of setting.

2. the down-going synchronous communication means of wireless base-station control node as claimed in claim 1 and distant-end node is characterized in that: the chip of described RRU at different levels ⁰The corresponding different Group of difference, described BBU determines RRU ^(N-1)Chip ⁰Corresponding Group numbering, RRU ^(N-1)Chip ⁰Corresponding Group ⁰, RRU ⁽ⁿ⁾Chip ⁰Corresponding Group ^K, described ^KValue is time interval T ^(N-1)-T ⁽ⁿ⁾The Group quantity that interior BBU can transmit to the RRU interface; The K value rounds, and is described ⁽ⁿ⁾Value 0～N-2; Described BBU is with described RRU chip at different levels ⁰Corresponding Group numbering is by the described RRU at different levels of Operation and Maintenance message informing.

3. the down-going synchronous communication means of wireless base-station control node as claimed in claim 2 and distant-end node is characterized in that: described BBU is according to described RRU chip at different levels ⁰Corresponding Group numbering is formed continuous Frame to described Group and is sent described Frame at the delivery time that described BBU sets.

4. the down-going synchronous communication means of wireless base-station control node as claimed in claim 3 and distant-end node is characterized in that: described Group ⁰Delivery time before the initial moment of Uu mouth radio frames, described Group ⁰Delivery time and the time difference between the initial moment of Uu mouth radio frames be T ^(N-1)With the Timing Advance sum.

5. the down-going synchronous communication means of wireless base-station control node as claimed in claim 4 and distant-end node, it is characterized in that: the time that described Timing Advance is handled downlink data frame greater than described RRU at different levels itself, the maximum time lead that can support less than described RRU spatial caches at different levels.

6. the down-going synchronous communication means of wireless base-station control node as claimed in claim 5 and distant-end node is characterized in that: described RRU receives described Operation and Maintenance message, knows the chip of this RRU ⁰Corresponding Group numbering ^K

7. the down-going synchronous communication means of wireless base-station control node as claimed in claim 6 and distant-end node is characterized in that: described RRU receives the Frame of BBU, determines Group by the method for frame synchronization ⁰The position, described RRU is from Group ⁰Begin counting, thereby can determine Group ^KThe position, and then can determine this RRU chip ⁰Original position, described RRU is according to chip ⁰Original position obtain the Frame of this RRU.

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