CN1093723C - Method for synchronizing all basic station over network in mobile communication system - Google Patents
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Abstract
The present invention relates to a method for synchronizing full-network base stations in a mobile communication system. The method comprises the following steps: a synchronous signal is generated in a clock module of a mobile exchanger; the generated synchronous signal is transmitted to each base station control module to obtain a synchronous signal with the same phase by a synchronous clock line; each base station obtains the synchronous signal from the base station control module to carry out delay adjustment. In the method for synchronizing full-network base stations, the synchronous signal is transmitted to the base stations by the transmission of the base station control modules, and the strict synchronization of the base stations in the whole mobile communication system is realized by the base station synchronization control of the delay adjustment. The optimum utilization of channel resources is realized, and the present invention supports the seamless station-crossing switch between the base stations.
Description
The present invention relates to the communication technology, be specifically related to a kind of all basic station over network simultaneous techniques that in based on the digital micro-honeycomb communication system of DECT or other mobile communication system that needs base station synchronization, realizes the channel resource optimum utilization and realize the seamless handoff between the base station.
DECT (the digitally enhanced wireless communication of Digital Enhanced Cordless Telecommunication) standard is the digital micro-honeycomb mobile communication standard of ETSI (European Telecommunication Standard institute) in issue in 92 years.Multi-access mode that DECT employing FDMA/TDMA combines and the ADPCM speech coding of 32kbps, support continuous dynamic channel allocation, bi-directional call and seamless handoff, have the ability of handling high traffic density: it not only supports voice service, also can support the data service up to 552kbps; DECT also provides with ISDN, X.25, the interface of network such as GSM, DECT unique technique advantage and characteristics have determined it can support multiple application (family expenses, commercial PBX, wireless local loop etc.) to have vast potential for future development.
The implication of DECT dynamic channel allocation is: DECT base station and terminal can work in any one channel in 120 channels, can work in all time slots of all carrier waves; The DECT terminal is connected and makes a call the channel of avoiding bad channel conditions automatically or having been taken by adjacent cell selecting a channel and base station to set up one; The DECT terminal in case find the busy channel variation, is replaced original channel with selecting a good channel else with after good the connection set up in the DECT base station at once.The characteristic of DECT dynamic channel allocation makes us not need frequency planning is carried out in each sub-district when doing the DECT system group network, thereby has improved the capacity of system greatly.
Concerning Digital Cellular System, the limited coverage area of each base station, if user's conversation in moving, signal quality is certain to descend when arriving covering edge, base station.This moment, mobile phone should have the ability to select a new channel, and automatically conversation was switched on the new channel, in this process, should guarantee the continuity conversed as far as possible, could satisfy user's demand.
The DECT mobile phone is monitored calling quality always when conversation, ceaselessly scan simultaneously the signal strength of sub-district and other channel of adjacent cell, mobile phone will be reselected the idle channel an of the best according to the signal strength table, if mobile phone is not crossed sub-district (being the base station signal that the signal of the detected current base station of mobile phone is better than adjacent cell) as yet, mobile phone will be set up a parallel speech path with current base station on the channel that chooses so, otherwise mobile phone will be set up a parallel speech path with a certain strong signal of adjacent cell base station on the channel that chooses.After new path setting was good, the base station just discharged original speech path.Because the switching of DECT is the process of " make-before-break ", we are referred to as " seamless switching ", " Ka Ka " sound that occurs in other cellular system switching has been eliminated in this switching, the possibility of call drop when having reduced to distinguish more, can satisfy fully family expenses, office with and public service proceed slowly in the continuous needs of conversation.
In the DECT micro cellular system, for the channel (time slot and frequency) that utilizes DECT best, and be the seamless handoff of supporting between the base station, must keep the synchronous of strictness between all base stations.Otherwise, if do not keep synchronously between the base station, for example frame of DECT, multi-frame, time slot, bit not alignment on time domain, at two sub-district adjacents owing to be subjected to the influence of two base stations simultaneously, its channel utilization can reduce greatly, also can't realize seamless handover.
The object of the present invention is to provide a kind of method for synchronizing all basic station over network in mobile communication system, utilize this method can overcome the above-mentioned shortcoming of prior art, strict synchronism between keeping between each base station, comprise between any two base stations the frame that keeps DECT, multi-frame, time slot, bit synchronously, thereby when making mobile communication occur in two sub-district adjacents, the assurance channel utilization is unaffected, and can support seamless handover.
The objective of the invention is to realize based on following thinking, promptly in system, adopt a unified synchronizing signal, deliver to each base station, realize the strict synchronism between each base station by transmission means, thereby utilize channel resource best, and support the seamless handoff between the base station.For realizing the purpose of base station synchronization, system at first will produce unique synchronizing signal in the system, and be sent to each base stations control module by system, each base stations control module is sent to each base station by the transmission line that is connected with the base station with synchronizing signal again, the base station utilizes through the adjusted synchronizing signal of time delay carries out base station synchronization, thereby reaches the synchronous purpose of all basic station over network.
The object of the present invention is achieved like this, construct a kind of method for synchronizing all basic station over network in mobile communication system: comprise the step that produces synchronizing signal, the base stations control module obtains the step of synchronizing signal, and each base station obtains described synchronizing signal and carries out the step that time delay is adjusted from the base stations control module.Method of the present invention has comprised the content of two aspects: the one, and synchronizing signal generation and base stations control module obtain the method for synchronizing signal; The 2nd, the base station obtains synchronizing signal from the base stations control module and carries out the time delay adjustment, and finishes the method for base station synchronization.
Because the selection of synchronizing signal is relevant with transmission means and base station synchronization mode, therefore talk from the second aspect content.
Base station and base stations control intermodule can adopt basic rate interface (be 2B+D, be referred to as u interface, meet G.960 standard of CCITT, wherein the B channel is the voice channel of 64kbps, and the D channel is the signaling channel of 16kbps) in the DECT system.The mode that realizes the u interface full duplex transmission at present mainly contains two kinds: time compression multiplex mode (Upn interface) and Echo Cancellation mode (Ukn interface).Therefore the transmission of base stations control module and synchronization among base stations signal need be undertaken by u interface, the base stations control module will convert synchronizing signal to the signal that is fit to the u interface transmission and deliver to the base station by u interface, promptly when synchronizing signal is low level, all U mouths of base stations control module are all synchronous with oneself multi-frame and synchronizing signal, and transmit synchronizing information on the suitable passage in U mouth multi-frame.Because each base station is different from the distance of base stations control module, therefore signal time delay difference on the U mouth line must record line delay, in advance after the base station extracts synchronizing signal from u interface, synchronizing signal is carried out the time delay adjustment, guarantee the synchronizing signal homophase that use each base station.Each base station utilizes the synchronizing signal rising edge to DECT frame, multi-frame, time slot, reset than top grade counter, thereby reaches the purpose of each base station signal frame, multi-frame, time slot, bit synchronous.
The selection of base station synchronization signal is relevant with transmission means and base station synchronization mode.DECT system base-station synchronous signal cycle should be the DECT integral multiple of multiframe period, like this base station obtain synchronizing signal carry out the first time synchronously after, only just can produce multi-frame by the synchronizing signal rising edge when abnormal conditions occurring and make multi-frame slide drag, drag otherwise when the synchronizing signal rising edge arrives, all can produce multi-frame, thereby operation brings adverse effect to system.Same, the base station synchronization signal period also should be the u interface integral multiple of multiframe period.The cycle that is to say DECT system base-station synchronizing signal should be the common multiple of DFCT multiframe period and u interface multiframe period.
The base station synchronization signal is that total system is unified, therefore should produce in mobile switch, delivers to each base stations control module by transmission means.The generation of base station synchronization signal and transmission means have two kinds:
1, the base station synchronization signal is produced by the clock module in the mobile switch, by the synchronised clock line synchronizing signal is sent to each base stations control module.When base stations control module and mobile switch distance was very near, propagation delay time was minimum, so the base station synchronization signal that each base stations control module extracts is a homophase;
2, in mobile system, the B channel interface between other modules of base stations control module and mobile switch is generally the 2M interface, can transmit 32 B channels, can voice-bearer (comprising speech and various prompt tone) on the B channel, business such as data.Therefore can produce the base station synchronization signal by the some public modules in the mobile switch, signal is left on the B channel (i.e. time slot) in the switch, by mobile with certain form
Switching network in the switch exchanges to this time slot on some time slots of the 2M interface that the base stations control module links to each other with mobile switch regularly, the base stations control module by from this fixedly time slot extraction signal just change and can restore the base station synchronization signal.When base stations control module and mobile switch distance was very near, propagation delay time was minimum, and because exchange is to adopt fixedly connectedly, so the base station synchronization signal that each base stations control module extracts is a homophase.The benefit of this mode is the hardware of original switch platform to be changed lack, and is convenient to realize.
Above dual mode all can reach the purpose that produces the base station synchronization signal and transfer the signal to the each base stations control module, can take which kind of mode according to the actual conditions decision during specific implementation.
Implement method for synchronizing all basic station over network provided by the invention, can in a mobile communication system, produce a base station synchronization signal, transmission by the base stations control module, synchronizing signal is sent to the base station, through time delay adjustment control base station synchronization, thereby realize the strict synchronism of each base station in the whole mobile communication system, realize the optimum utilization of channel resource, and support the seamless handoff between the base station.
In conjunction with the accompanying drawings and embodiments, further specify characteristics of the present invention, in the accompanying drawing:
Fig. 1 is the structural representation that the embodiment of the invention is used the DMC1900 system;
Fig. 2 is in explanation the inventive method, the schematic diagram of synchronization signal extraction circuit;
Fig. 3 illustrates in the methods of the invention, the transfer process schematic diagram of synchronizing signal in system
Fig. 4 illustrates in the inventive method, the principle schematic that the time measurement when adopting time compression multiplex mode interface postpones;
Fig. 5 illustrates in the inventive method, the principle schematic that the time measurement when adopting Echo Cancellation mode interface postpones.
This method is embodied in based in the commercial digital micro-honeycomb of the DMC1900 of the DECT technology system.The structure of this system as shown in Figure 1.As shown in Figure 1, the DMC1900 system comprises mobile switch 100 (WPBX), Operation and Maintenance platform 200, is embedded in the several sections such as base stations control module BSC (not shown), base station 300 (BS) and mobile phone 400 in the mobile switch 100.Wherein, mobile switch 100 can be the C﹠amp of Huawei Company; The C08 switch platform, base stations control module BSC is embedded in the mobile switch 100.Adopt basic rate interface (U mouth) between base stations control module BSC and base station BS (300), both can adopt the Ukn interface, also can adopt the Upn interface.In order to realize of the transmission of base station synchronization signal by the U mouth, select u interface chip in the system for use with U mouth synchronizing function, the U mouth chip that wherein adopts the Upn mode is to being: PEB2096 and PEB2196, the U mouth chip that adopts the Ukn mode is to being: PEB24902+PEB24911 and PEB2091.In the base station, select for use PMB2727 as the BMC controller.
In order to realize base station synchronization, in mobile switch, produce a base station synchronization signal.For the DECT system, the base station synchronization signal period must be the integral multiple of DECT 160ms multiframe period.For the Upn interface, the base station synchronization signal period must be the integral multiple of Upn interface 1ms multiframe period, and the base station synchronization signal period must be the integral multiple of 160ms when adopting the Upn interface so, and it is the integral multiple of 800ms that PEB2096 requires U mouth synchronous signal cycle; For the Ukn interface, the base station synchronization signal period must be the integral multiple of Ukn interface 12ms multiframe period, and the base station synchronization signal period must be the integral multiple of 480ms (least common multiple of 160ms and 12ms) when adopting the Ukn interface so.For take into account under Upn and the Ukn dual mode synchronously, selecting the cycle of base station synchronization signal is the integral multiple of 2400ms (least common multiple of 800ms and 480ms).
The base station synchronization signal period is 2.4S in the DMC1900 system, and wherein low duration is 125us.The generation of this synchronizing signal and the mode that is sent to BSC have adopted the second way, and it is very little to adopt this mode that original hardware platform is changed, and have simplified the complexity that realizes.
In mobile switch, (be the SIG plate, the SIG plate is C﹠amp to utilize Signal Tone board SIG; Produce digital tone signal required in the switch handshaking procedure in the C08 switch, teach generation to answer voice, and provide give the correct time, the veneer of recording and reproducing function such as weather forecast) an idle time slot (TS30) the storage one-period of output HW is that (2.4S is equivalent to 19200 frames for the digital signal of 2.4S, data on the TS30 are to change in the cycle with 19200 frames, data in the one-period on the continuous 19199 frame TS30 are 00H, and the data on the 1 frame TS30 are FFH.This can realize by the content of revising EPROM on the SIG plate).Each base stations control module BSC all links to each other with mobile switch by two 2M mouths (being called two HW) in the system, by the network board in the mobile switch (the NET plate, the NET plate is C﹠amp; Finish the veneer of time gas exchange function in the c08 switch) TS30 of SIG plate output HW is exchanged on the TS1 of each base stations control module idol HW regularly, this can be by revising the fix exchange and indicate occupied can the realization of TSI of even HW of mobile switch software.
On the base stations control module, (promptly go up the level height of the value decision output synchronizing signal of data by hardware from the TS1 extraction base station synchronization signal of even HW according to TSI, when the last data of TSI are 00H, synchronizing signal is got high level, when the last data of TSI are FFH, synchronizing signal is got low level, thereby obtained the synchronizing signal of 2.4S, wherein low duration is 125us, and it is synchronous with frame synchronizing signal FSC, hardware block diagram as shown in Figure 2, because the base stations control module is embedded in the mobile switch, when transmission range was very near, propagation delay time was minimum, and because exchange is that employing is fixedly connected, so the base station synchronization signal that each base stations control module extracts is a homophase.
The base stations control module is input to the base station synchronization signal on the U mouth chip (PEB2096 or PEB24902+PEB24911), by U mouth chip synchronizing signal is converted to and to be suitable for the defeated signal of U oral instructions (promptly when synchronizing signal is low level, U mouth chip controls U mouth is synchronous with oneself multi-frame and synchronizing signal, and transmits synchronizing information on the suitable passage in U mouth multi-frame).The base stations control module is carried out latency measurement to each U mouth simultaneously, latency measurement (concrete method of measurement the is attached) function that provides by U mouth chip records the length of delay of U mouth circuit, length of delay is converted to the form that is applicable to that PMB2727 uses, length of delay after will changing by 9 (D) channel sends the base station end to, and the CPU of base station composes the delay time register of giving PMB2727 with this value.
At the base station end, the U mouth chip of base station is mapped to the synchronizing information in the U mouth multi-frame on the S/G bit of IOM-2 bus, after BMC controller (PMB2727) detects synchronizing information on the S/G bit, value according to delay time register, after S/G bit rising edge is done suitable time-delay to such as scanning, DECT frame and multi-frame, time slot, and (or) than top grade counter reset, thereby reach the purpose of base station synchronization.
The transmission path of synchronizing signal as shown in Figure 3 in the whole system.
Experimental result shows, can reach the purpose of DMC1900 system whole-network base station synchronization by said method, realizes the optimum utilization of channel resource, and supports the seamless handoff between the base station.
Producing by public module in the mobile switch under the situation of synchronizing signal, each base station will be according to the adjustment of delaying time of the distance of itself and base stations control module.For this reason, must consider delay measuring method.
According to DECT agreement (ETS300175), the synchronous tolerance between two base stations is+/-2us, be equivalent to approximately+/-the U mouth line length of 1km.Can so understand,,, then not influence synchronous between each base station if line delay is not handled when the length of U mouth line during (not synteny, this be worth different) less than about 1km.
Otherwise, when line length greater than 1km, just must handle retardation.
When adopting basic rate interface (U mouth) between base stations control module BSC and base station BS, both can adopt the Ukn interface, also can adopt the Ukn interface.In order to realize of the transmission of base station synchronization signal by the U mouth, in a pilot system of the inventive method, select u interface chip for use with U mouth synchronizing function, the U mouth chip that wherein adopts the Upn mode is to being: PEB2096 and PEB2196, the U mouth chip that adopts the Ukn mode is to being: PEB24902+PEB24911 and PEB2091.In the base station, select for use PMB2727 as the BMC controller.
No matter to Upn still to Ukn, the process of processing is as follows:
1. at base stations control module end measurement circuitry length of delay.
2. length of delay is converted to the form that is applicable to that PMB2727 uses.
3. the retardation after will changing by 9 (D) passage is passed to the base station end.
The CPU of base station composes the delay time register of giving PMB2727 with this value.
Delay measurements with 24902,24911 and 2091 of the U mouth chips of Ukn mode is described as follows:
At first, retardation is defined as: the time interval on FSC on the base stations control module (frame synchronizing signal) and the base station between the FSC.Next sets resolution is 260ns, so the quantification step of its retardation is 260ns.Its measuring process is described below: 1) after PEB24911 enters full activation (Transparent) state, can carry out delay measurements at any time.Even U mouth line length is constant, but as if temperature not simultaneously, its length of delay also can be different; 2) delay measurements of each U mouth is controlled by issue MON-8 order RPDU on their Monitor down going channels separately, and each U choma road and two ends chip are finished measurement automatically, and its length of delay APDU reports the CPU of base stations control module by the MOU data feedback channel.The length of delay APDU that is surveyed comprises that T goes up EF, U6, LLINE, as shown in Figure 4.
U mouth chip 2196 and 2096 delay measurements with the Upn mode
At first retardation is defined as: the time interval between the LF bit in 2096 the multi-frame in a bit and the recovery frame; Secondly, resolution can obtain different resolution according to different settings.For example,
65ns: can survey maximum delay weight range 16.57us;
135ns: can survey maximum delay weight range 33.15us.
Measuring process is described below, and must select the U mouth that need carry out delay measurements and resolution etc. by the Configuration register in the PEB2096, afterwards, begins automatically to measure, and its result deposits the Delay register automatically in.This value can be read by the Monitor passage.
Length of delay in the Delay register: T_d=Tm_lf+Tt_r-tg
Wherein: Tm_lf is the delay of sending out between M bit and the receipts LF bit;
Tt_r is the delay of the analog channel of transmitter and receiver:
Tg is the guard time of two bits;
T-d is two-way time of delay, and actual one-way latency should be td=T_d/2.As shown in Figure 5.Wherein, tr is a brust cycle.
Method of the present invention also can be used to adopt the base station synchronization of other mobile communication system that u interface connects, but need do necessary modifications according to actual conditions.
Claims (5)
1, a kind of method for synchronizing all basic station over network in mobile communication system, described mobile communication system comprises mobile switch, is embedded in the interior base stations control module of mobile switch, adopts 2B+D with described base stations control module is the base station that the u interface full duplex is connected, and described method for synchronizing all basic station over network may further comprise the steps:
Produce a base station synchronization signal by a public module in the described mobile switch, the B channel that this synchronizing signal is deposited in the described mobile switch is on the time slot, the form of depositing of this synchronization signal data is that natural period with this base station synchronization signal is to carry out complete 0 complete 1 variation the cycle, the time slot that will be loaded with described base station synchronization signal by the switching network in the described mobile switch exchanges on the time slot of the 2M interface that described base stations control module links to each other with described mobile switch regularly then, described base stations control module is mentioned signal by this time slot and is carried out level and just just change and can restore the base station synchronization signal, after the synchronizing signal of extracting from described base stations control module is transmitted by u interface in described base station, adjust accordingly to guarantee the synchronizing signal homophase of each base station use according to the time delay that records in advance in advance.
2, method according to claim 1, it is characterized in that, described base stations control module converts synchronizing signal to the signal that is fit to the u interface transmission by u interface, deliver to the base station by u interface, promptly when synchronizing signal is low level, all U mouths of base stations control module are all synchronous with oneself multi-frame and synchronizing signal, and transmit synchronizing signal on the suitable passage in U mouth multi-frame.
3, method according to claim 1 is characterized in that, the cycle of the synchronizing signal that is produced by described mobile switch is the common multiple of DECT multiframe period and u interface multiframe period.
4, method according to claim 1 is characterized in that, described u interface full duplex ways of connecting comprises time compression multiplex mode (Upn interface) and Echo Cancellation mode (Ukn interface) between described base stations control module and the described base station.
5, method according to claim 1 is characterized in that, described each base station utilizes the synchronizing signal rising edge to DECT frame, multi-frame, time slot, reset than top grade counter, thus realize each base station signal frame, multi-frame, time slot, bit synchronously.
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| CN98118799A CN1093723C (en) | 1998-09-04 | 1998-09-04 | Method for synchronizing all basic station over network in mobile communication system |
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| CN98118799A CN1093723C (en) | 1998-09-04 | 1998-09-04 | Method for synchronizing all basic station over network in mobile communication system |
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| CN1093723C true CN1093723C (en) | 2002-10-30 |
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Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP4279777B2 (en) * | 2003-12-24 | 2009-06-17 | 株式会社エヌ・ティ・ティ・ドコモ | Mobile communication system and control device |
| CN100426700C (en) * | 2004-08-10 | 2008-10-15 | 中兴通讯股份有限公司 | Synchronization mode for GPS base station in personal portable telephone system |
| GB2431073B (en) * | 2005-10-10 | 2008-05-14 | Ipwireless Inc | Cellular communication system and method for co-existence of dissimilar systems |
| CN101378342B (en) * | 2007-08-28 | 2010-12-08 | 鸿富锦精密工业（深圳）有限公司 | System and method for judging U interface status |
| US8654796B2 (en) | 2008-03-03 | 2014-02-18 | Zte Corporation | System for synchronizing clock |
| CN101527959B (en) * | 2008-03-03 | 2012-09-05 | 中兴通讯股份有限公司 | Clock synchronization system |
| CN103096457B (en) * | 2013-01-18 | 2016-06-29 | 苏州智铸通信科技有限公司 | TDD base station synchronization method based on external reference clock and sub-frame sync signal |
| US10547435B2 (en) | 2016-03-14 | 2020-01-28 | Industrial Technology Research Institute | Configuration and measurement method for performing a full-duplex communication and base station using the same |
| CN106385707B (en) * | 2016-09-18 | 2019-10-22 | 广州市大喜通信技术有限公司 | A kind of TD-LTE automatic delay method of adjustment and device |
| CN110167089B (en) * | 2019-06-19 | 2021-07-30 | 北京中兴高达通信技术有限公司 | Network equipment, wireless communication system and channel switching method |
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| CN1088721A (en) * | 1992-10-02 | 1994-06-29 | 莫托罗拉公司 | In communication system in order to the apparatus and method of base station synchronizationization to be provided |
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| EP0803994A2 (en) * | 1996-04-22 | 1997-10-29 | Italtel s.p.a. | Method to obtain and synchronize the radio multiframe number in DECT cordless systems |
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| CN1088721A (en) * | 1992-10-02 | 1994-06-29 | 莫托罗拉公司 | In communication system in order to the apparatus and method of base station synchronizationization to be provided |
| CN1111468A (en) * | 1993-07-12 | 1995-11-08 | Ntt移动通信网株式会社 | Interoffice phase synchronizing system |
| EP0803994A2 (en) * | 1996-04-22 | 1997-10-29 | Italtel s.p.a. | Method to obtain and synchronize the radio multiframe number in DECT cordless systems |
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