CN101075848B - System and method for synchronizing microcellular network base station and base station - Google Patents

Abstract

The embodiment of the present invention discloses a method for synchronizing base stations of a micro-cellular network. The method includes: the macro base station broadcasts the absolute time on the network side; the micro base station obtains the transmission delay between itself and the macro base station, and uses the transmission delay and receiving The received absolute time on the network side adjusts the local working time to achieve time synchronization. The invention discloses a system for synchronizing base stations of a microcellular network, a micro base station and a macro base station. By adopting the invention, the time synchronization of the base station of the microcellular network can be realized at a lower cost.

Description

Method, system and base station for synchronizing base stations of microcellular network

technical field

The invention relates to the field of wireless communication, in particular to a method, a system and a base station for synchronizing base stations of a microcellular network.

Background technique

With the continuous growth of data services, the future network configuration will increasingly include a layered coverage network with a hybrid network of macro cells and micro cells. The macro cell achieves wide coverage and provides lower-speed service connections; the micro cell achieves micro-cell coverage and provides high-speed, high-capacity service connections. The systems and frequency bands used by the two can be the same or different. For example, macro cells can adopt 2G systems such as Global Mobile Communications (GSM) and Code Division Multiple Access (CDMA), or 3G systems such as Wideband Code Division Multiple Access (WCDMA), and micro cells can use wireless local area networks (WiFi) , Digital European Cordless Telephone (DECT), Worldwide Interoperability for Microwave Access (WiMAX) and other systems.

In a layered coverage network, the number of base stations of a microcellular network, referred to as micro base stations, is huge, and a base station of a macrocellular network on the top layer, referred to as a macro base station, may cover a large number of micro base stations at the bottom. For the microcellular network, the business carried by the bearer is suitable for packet business, so it is suitable for the backhaul connection of packet switching. However, backhaul connections in packet form are inconvenient for providing cell synchronization and time reference. Although protocols such as IEEE 1588 and Synchronous Ethernet have been proposed, there are still many limitations in practicality. The micro base station can also adopt the global positioning system (GPS) synchronization, that is, obtain the unified absolute time of the whole network from the GPS, and adjust the local time to the absolute time to achieve the synchronization of the base stations of the microcellular network. However, under this synchronization mechanism, the infrastructure cost of the micro base station is relatively high, and is limited by the control and coverage of GPS.

Contents of the invention

Embodiments of the present invention provide a method, system and device for synchronizing a microcellular network base station, which are used to solve the problems in the prior art that the synchronization of microcellular base stations is expensive and limited by GPS control and coverage.

An embodiment of the present invention provides a method for synchronizing base stations of a microcellular network, the method comprising:

The absolute time of the broadcast network side of the macro base station;

The micro base station obtains the transmission delay between itself and the macro base station according to the obtained distance between itself and the macro base station or the time advance TA value information sent by the macro base station, and uses the transmission delay and the received The absolute time on the network side adjusts the local working time;

The transmission delay between the micro base station and the macro base station obtained by the micro base station according to the TA value information sent by the macro base station includes:

The macro base station broadcasts a time reference signal;

The micro base station receives the time reference signal, and sends a random access request to the macro base station at a time allowed by the network side according to the time reference signal;

The macro base station receives the random access request, calculates the TA value, and sends the TA value information to the micro base station; the method for calculating the TA value is: the first request receiving time minus the second request receiving time, where The difference is the TA value, where the first request receiving time is the time when the macro base station receives the random access request from the micro base station in the random access channel, and the second request receiving time is the time when the macro base station receives the random access request from the micro base station in the random access channel The time at which a random access request from a terminal whose expected distance from the macro base station is 0 is received;

The micro base station divides the TA value by 2 to obtain the transmission delay between the micro base station and the macro base station;

The time reference signal also includes frequency synchronization information, then the method further includes:

The micro base station extracts the frequency synchronization information in the time reference signal, and uses the extracted frequency as a clock frequency source for its own work.

An embodiment of the present invention provides a system for synchronizing base stations of a microcellular network, the system comprising:

The macro base station includes a first broadcast unit, a second broadcast unit, and a processing unit; the first broadcast unit is used to broadcast the absolute time on the network side; the second broadcast unit is used to periodically broadcast a time reference signal; the processing The unit is used to receive the random access request sent by the micro base station, calculate the time advance TA value, and send the TA value information to the micro base station; the method of calculating the TA value is: the first request receiving time minus the second Request receiving time, the difference is the TA value, wherein, the first request receiving time is the time when the macro base station receives the random access request from the micro base station in the random access channel, and the second request receiving time is the time when the macro base station receives the random access request from the micro base station in the random access channel. The time at which a random access request from a terminal whose expected distance from the macro base station is 0 is received in the random access channel;

The micro base station includes a wireless transceiver unit, a delay unit, and a time synchronization unit working in a terminal mode of a macro cellular system; the wireless transceiver unit is used to communicate with the macro base station, including receiving the absolute time of the network side, and receiving the time reference signal, sending a random access request to the macro base station at a time allowed by the network side according to the time reference signal, and receiving the TA value information; the delay unit includes a second calculation unit, configured to The TA value is divided by 2 to obtain the transmission delay between the micro base station and the macro base station; the time synchronization unit is configured to use the network-side absolute time and the transmission delay to adjust a local working time.

An embodiment of the present invention provides a macro base station, the macro base station includes:

The first broadcast unit is used to broadcast the absolute time on the network side;

The second broadcast unit is used to broadcast the time reference signal;

The processing unit is used to receive the random access request sent by the micro base station, calculate the time advance TA value, and send the TA value information to the micro base station; the method of calculating the TA value is: the first request receiving time minus the second Two request receiving times, the difference between which is the TA value, where the first request receiving time is the time when the macro base station receives the random access request from the micro base station in the random access channel, and the second request receiving time is the time when the macro base station receives the random access request from the micro base station The time at which a random access request from a terminal with an expected distance of 0 from the macro base station is received in the random access channel.

An embodiment of the present invention provides a micro base station, the micro base station includes:

The wireless transceiver unit working in the terminal mode of the macro cellular system is used to communicate with the macro base station, including receiving the absolute time of the network side sent by the macro base station, and receiving the time reference signal sent by the macro base station. According to the time reference signal in the Sending a random access request to the macro base station at a time allowed by the network side, and receiving time advance TA value information from the macro base station;

a delay unit, including a second calculation unit, configured to divide the TA value by 2 to obtain a transmission delay between the micro base station and the macro base station;

A time synchronization unit, configured to use the transmission delay and the received absolute time on the network side to adjust the local working time.

The beneficial effect of the present invention is that: in the synchronization solution provided by the embodiment of the present invention, the micro base station obtains the absolute time of the network side from the macro base station, and adjusts the local working time by using the transmission delay between itself and the macro base station and the received absolute time of the network side, Time synchronization is achieved. This method of realizing time synchronization through information interaction between the micro base station and the macro base station has low cost and is no longer limited by the control and coverage of GPS.

Description of drawings

Fig. 1 is a system networking diagram applied by the method provided by the embodiment of the present invention;

Fig. 2 is the flow chart of the method provided by the embodiment of the present invention;

FIG. 3 is a structural diagram of a macro base station provided by an embodiment of the present invention;

FIG. 4A is a structural diagram of a micro base station provided by an embodiment of the present invention;

FIG. 4B is a schematic diagram of an internal structure of a micro base station provided by an embodiment of the present invention.

Detailed ways

In order to reduce the facility cost for synchronizing the base stations of the microcellular network, an embodiment of the present invention provides a method for synchronizing the base stations of the microcellular network. Synchronization of base stations.

Referring to FIG. 1 , it is a network diagram of a system to which the method of the present invention is applied. The system includes a macro base station, a micro base station, a gateway (GW) and a user terminal (UE).

Among them, the information channels 1, 2, 4, and 5 between the macro base station and GW, the micro base station and GW, the micro base station and UE, and the macro base station and UE are existing in the prior art. The information channel 3 between the base stations enables the macro base station and the micro base station to communicate with each other. Since the micro base station is geographically located within the coverage of the macro base station, the two base stations can communicate through the air interface. In specific implementation, a wireless terminal of a macro cellular system can be integrated in the micro base station for communication with the macro base station. The wireless terminal does not need to be a complete terminal, but only needs to have the function of wireless transmission and reception.

A method for synchronizing base stations of a microcellular network provided by an embodiment of the present invention, the specific process is as follows:

Step 201: The macro base station periodically broadcasts the absolute time on the network side;

Step 202: When the micro base station receives the network-side absolute time (network time) broadcast by the macro base station, obtain the local absolute time (local time) according to the network-side absolute time and the transmission delay (PD) between the micro base station and the macro base station , and adjust the local working time to the local absolute time to complete time synchronization.

In this step, the transmission delay between the micro base station and the macro base station can be obtained through the distance between the micro base station and the macro base station or the time advance/time adjustment (TA) value measured by the macro base station.

Among them, the transmission delay is obtained through the distance between the micro base station and the macro base station. There are two specific methods as follows:

The first one is to configure the distance information between the micro base station and the macro base station artificially measured by geographical coordinates etc. in the micro base station, and the micro base station calculates the transmission delay between the micro base station and the macro base station according to the distance information, for example, the The distance value between the micro base station and the macro base station is divided by the propagation speed of electromagnetic waves in free space to obtain the transmission delay between the micro base station and the macro base station.

The second is to use the positioning service of the network to obtain the distance value between the micro base station and the macro base station, so as to calculate the transmission delay. For example, for a WCDMA system, the distance information between the micro base station and the macro base station can be obtained by using the positioning method such as the cell-ID return time (cell-ID+RTT), and then the distance between the micro base station and the macro base station can be obtained according to the distance information. For transmission delay, for example, the distance value between the micro base station and the macro base station is divided by the propagation speed of electromagnetic waves in free space to obtain the transmission delay between the micro base station and the macro base station.

The specific method of obtaining the transmission delay between the micro base station and the macro base station through the time advance/time adjustment (TA) value measured by the macro base station is as follows, as shown in Figure 2:

Step S1: The macro base station periodically broadcasts the time reference signal through the broadcast channel;

Step S2: The micro base station receives the time reference signal broadcast by the macro base station, and sends a random access request to the macro base station at a time allowed by the network side according to the time reference signal;

Step S3: The macro base station receives the random access request sent by the micro base station, calculates the TA value, and sends an immediate assignment signal containing the TA value to the micro base station;

Here, the calculation method of the timing advance amount TA is: the first request receiving time minus the second request receiving time, and the difference is the TA value, wherein the first request receiving time is received by the macro base station in the random access channel The time of the random access request from the micro base station, the second request receiving time is the time when the macro base station receives the random access request from the terminal whose expected distance from the macro base station is 0 in the random access channel, and the time is determined according to the protocol Sure.

Step S4: After obtaining the TA value, the Femtocell calculates the transmission delay (PD): PD=TA/2, and uses the PD value and the received absolute time from the network side broadcast by the Macrocell to obtain the local absolute time.

In step 201, the absolute time on the network side periodically broadcast by the macro base station may be the working time of the clock of the macro base station itself, or may be a unified synchronized absolute time on the network side. When this time is the clock working time of the macro base station itself, the time synchronization of all micro base stations under the layered coverage of the macro base station can be realized; Time synchronization can realize the time synchronization of micro base stations in the whole network.

At the same time, the specific method for the micro base station to obtain the local time according to the transmission delay and the received network time broadcast by the macro base station is: local time=network time+PD, that is, the local absolute time is the absolute time of the network side received by the micro base station, and taking into account The difference caused by the transmission delay.

This step is periodic, and the absolute time broadcast period on the network side is set by the macrocellular network.

In this method, the frequency synchronization of the micro base station can also be realized, and the specific method can be:

The macro base station periodically broadcasts the time reference signal through the broadcast channel, which contains frequency synchronization information; the micro base station receives the time reference signal broadcast by the macro base station, extracts the frequency synchronization information, and uses the extracted frequency as the frequency clock source for its own work to complete the frequency synchronization. Synchronize.

Referring to FIG. 3, the embodiment of the present invention also provides a macro base station, which can be applied to the system shown in FIG. 302, for broadcasting the time reference signal; the processing unit 303, for receiving the random access request sent by the micro base station, obtaining a TA value according to the receiving time and the broadcast time of the time reference signal, and sending the TA to the micro base station value information.

The specific work flow of the macro base station provided by the embodiment of the present invention is described below:

The first broadcast unit of the macro base station periodically broadcasts the absolute time on the network side, and the absolute time on the network side is the clock working time of the base station itself, or the unified synchronized absolute time on the network side;

The second broadcast unit of the macro base station broadcasts the time reference signal;

When the processing unit of the macro base station receives the random access request sent by the micro base station, it calculates the TA value according to the receiving time, and sends the TA value information to the micro base station. The calculation of the TA value is the same as the method part, that is, subtract the access time from the terminal whose expected distance is 0 from the time of receiving the random access request to obtain the TA value.

Referring to FIG. 4A and FIG. 4B, an embodiment of the present invention also provides a micro base station, which can be applied to the system shown in FIG. 1, and the micro base station includes:

The wireless transceiver unit 401 working in the terminal mode of the macro cellular system is used to communicate with the macro base station, including receiving the time reference signal from the macro base station, the absolute time signal on the network side, and sending random Access signals, receive immediate assignment signals containing TA value information, obtain location information from positioning services, etc.;

The control unit 402 is configured to control the information interaction with the macro base station when obtaining the transmission delay, such as instructing to send a random access request to the macro base station when receiving the time reference signal broadcast by the macro base station; When the immediately assigned signal containing TA value information, record the TA value; when receiving the network-side absolute time signal broadcast by the macro base station, calculate the local absolute time, and adjust the working time of the local transceiver (TRX) to The calculated local absolute time makes the local time consistent with the network side time of the macro base station, achieving time synchronization. At the same time, frequency synchronization can also be realized.

The control unit 402 may specifically include: a delay unit 4021, configured to obtain the transmission delay between itself and the macro base station according to the distance between the micro base station and the macro base station or the time advance TA value information; a time synchronization unit 4022, used to utilize The transmission delay and the received absolute time on the network side adjust the local working time, that is, the absolute time on the network side is added to the transmission delay to obtain the local absolute time, and the local working time is adjusted to the local absolute time .

The delay unit 4021 includes: a first calculation unit 40211, configured to divide the distance between the micro base station and the macro base station by the propagation speed of electromagnetic waves in free space to obtain the transmission delay between the micro base station and the macro base station, so The distance between the micro base station and the macro base station can be obtained through the positioning service provided by the network side, or obtained from the information configured by the user; the second calculation unit 40212 is used to divide the TA value sent by the macro base station by 2 to obtain Transmission delay between the micro base station and the macro base station.

The control unit 402 may also include: a frequency synchronization unit 4023, configured to extract the frequency synchronization information in the signal when the time reference signal sent by the macro base station contains frequency synchronization information, and use the extracted frequency as the clock frequency for its own work source for frequency synchronization.

The specific workflow of the micro base station provided by the embodiment of the present invention is described below:

Step S11: the wireless transceiver unit of the micro base station receives the time reference signal broadcast by the macro base station;

Step S12: the control unit of the micro base station instructs the wireless transceiver unit to send a random access request to the macro base station at a time allowed by the network side;

Step S13: The wireless transceiver unit of the micro base station receives the immediate assignment signal containing TA value information sent by the macro base station, and the control unit records the TA value;

Step S14: The wireless transceiver unit of the micro base station receives the network-side absolute time broadcast by the macro base station, and the control unit obtains the local absolute time according to the network-side absolute time and the TA value recorded in step S13 and performs time adjustment;

Specifically, the second calculation unit of the delay unit included in the control unit divides the TA value sent by the macro base station by 2 to obtain the transmission delay between the micro base station and the macro base station; the time synchronization unit included in the control unit divides the The absolute time on the network side is added to the transmission delay to obtain the local absolute time, and the local working time is adjusted to the local absolute time to realize time synchronization.

In summary, the beneficial effects of the present invention are:

In the micro base station synchronization solution provided by the embodiment of the present invention, the micro base station obtains the absolute time and TA value information on the network side from the broadcast channel of the macro base station, and obtains the transmission delay between the micro base station and the macro base station according to the TA value information, and then according to the network The absolute time on the side and the transmission delay are used to obtain the local absolute time, and the local working time is adjusted to the local absolute time to achieve time synchronization. Alternatively, the micro base station obtains the distance information through the positioning service provided by the network side or user configuration, obtains the transmission delay between the micro base station and the macro base station according to the distance information, and then obtains the local absolute time according to the absolute time of the network side and the transmission delay, and The local working time is adjusted to the local absolute time to achieve time synchronization.

At the same time, the micro base station can also obtain frequency synchronization information from the broadcast channel of the macro base station, and use the extracted frequency as its own working clock frequency to achieve frequency synchronization.

This method of realizing time synchronization and frequency synchronization through information interaction between the micro base station and the macro base station has low cost and is no longer limited by the control and coverage of GPS.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies thereof, the present invention also intends to include these modifications and variations.

Claims (14)

1. the method that microcellular network basestation is synchronous is characterized in that, this method comprises:

Macro base station broadcast network side absolute time;

Little base station shifts to an earlier date the TA value information according to self that obtains with the distance of described macro base station or the time of described macro base station transmission, obtain the transmission delay between self and the described macro base station, utilize described transmission delay and the described network side absolute time that receives is adjusted the local operating time;

Little base station is according to the TA value information that described macro base station sends, and the transmission delay that obtains between self and the described macro base station comprises:

Described macro base station airtime reference signal;

Described little base station receives described timing reference signal, sends at random insert request in the moment that network side allows to described macro base station according to this timing reference signal;

Described macro base station receives the described request that inserts at random, calculates the TA value, and this TA value information is sent to described little base station; The method of calculating the TA value is: the first request time of reception deducts the second request time of reception, its difference is the TA value, wherein, the first request time of reception is that macro base station receives the time of inserting request at random from little base station in Random Access Channel, the second request time of reception be macro base station in Random Access Channel, receive from the macro base station desired distance be the time of the request that inserts at random of 0 terminal;

Described little base station divided by 2, obtains the transmission delay between described little base station and the described macro base station with described TA value;

Also comprise frequency synchronization information in the described timing reference signal, then this method further comprises:

The frequency synchronization information in the described timing reference signal is extracted in described little base station, and with the frequency the extracted clock frequency source as self work.

2. the method for claim 1 is characterized in that, described little base station comprises according to the transmission delay that the distance of self and the described macro base station that obtain obtains between self and the described macro base station:

The distance of described little base station and described macro base station divided by the free space propagation velocity of electromagnetic wave, is obtained the transmission delay between described little base station and the described macro base station.

3. method as claimed in claim 2 is characterized in that, the positioning service that described little base station provides by network side obtains the distance of self and described macro base station, perhaps obtains from user configured information.

4. the method for claim 1 is characterized in that, described network side absolute time is the clock work time of described macro base station self, or the unified synchronous absolute time of network side.

5. the method for claim 1 is characterized in that, described macro base station periodic broadcasting network side absolute time or timing reference signal.

6. the system that microcellular network basestation is synchronous is characterized in that, this system comprises:

Macro base station comprises first radio unit, second radio unit and processing unit; Described first radio unit is used for the broadcast network side absolute time; Described second radio unit is used for the periodic broadcasting timing reference signal; Described processing unit is used to receive the request of access at random of sending little base station, shifts to an earlier date the TA value computing time, and this TA value information is sent to described little base station; The method of calculating the TA value is: the first request time of reception deducts the second request time of reception, its difference is the TA value, wherein, the first request time of reception is that macro base station receives the time of inserting request at random from little base station in Random Access Channel, the second request time of reception be macro base station in Random Access Channel, receive from the macro base station desired distance be the time of the request that inserts at random of 0 terminal;

Little base station comprises the wireless transmit/receive units with terminal mode work, delay cell and the time synchronized unit of macrocellular standard; Described wireless transmit/receive units, be used for communicating, comprise receiving described network side absolute time, and receive described timing reference signal with described macro base station, send at random insert request in the moment that network side allows to described macro base station according to this timing reference signal, receive described TA value information; Described delay cell comprises second computing unit, is used for described TA value obtaining the transmission delay between described little base station and the described macro base station divided by 2; Described time synchronized unit is used to utilize described network side absolute time and described transmission delay to adjust the local operating time.

7. system as claimed in claim 6 is characterized in that, described delay cell also comprises:

First computing unit is used for distance with described little base station and described macro base station divided by the free space propagation velocity of electromagnetic wave, obtains the transmission delay between described little base station and the described macro base station.

8. system as claimed in claim 6 is characterized in that, described little base station further comprises:

The Frequency Synchronization unit is used for extracting the frequency synchronization information in this signal when described timing reference signal comprises frequency synchronization information, and with the frequency the extracted clock frequency source as self work.

9. system as claimed in claim 6 is characterized in that, described network side absolute time is the clock work time of described macro base station self, or the unified synchronous absolute time of network side.

10. a macro base station is characterized in that, this macro base station comprises:

First radio unit is used for the broadcast network side absolute time;

Second radio unit is used for the airtime reference signal;

Processing unit is used to receive the request of access at random of sending little base station, shifts to an earlier date the TA value computing time, and this TA value information is sent to described little base station; The method of calculating the TA value is: the first request time of reception deducts the second request time of reception, its difference is the TA value, wherein, the first request time of reception is that macro base station receives the time of inserting request at random from little base station in Random Access Channel, the second request time of reception be macro base station in Random Access Channel, receive from the macro base station desired distance be the time of the request that inserts at random of 0 terminal.

11. macro base station as claimed in claim 10 is characterized in that, the network side absolute time of described first radio unit broadcasting is the clock work time of described macro base station self, or the unified synchronous absolute time of network side.

12. a little base station is characterized in that, this little base station comprises:

The wireless transmit/receive units with terminal mode work of macrocellular standard, be used for communicating with macro base station, comprise and receive the network side absolute time that macro base station is sent, and receive the timing reference signal that macro base station is sent, send at random insert request in the moment that network side allows to described macro base station according to this timing reference signal, the time that the reception macro base station is sent shifts to an earlier date the TA value information;

Delay cell comprises second computing unit, is used for described TA value obtaining the transmission delay between described little base station and the described macro base station divided by 2;

The time synchronized unit is used to the described local operating time of network side absolute time adjustment of utilizing described transmission delay and receiving.

13. little base station as claimed in claim 12 is characterized in that, described delay cell also comprises:

First computing unit is used for distance with described little base station and described macro base station divided by the free space propagation velocity of electromagnetic wave, obtains the transmission delay between described little base station and the described macro base station.

14. little base station as claimed in claim 12 is characterized in that, described little base station further comprises:

The Frequency Synchronization unit is used for extracting the frequency synchronization information in this signal when described timing reference signal comprises frequency synchronization information, and with the frequency the extracted clock frequency source as self work.

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