CN112135326A - TAU switching method based on compatibility of WLAN networking and LTE networking - Google Patents
TAU switching method based on compatibility of WLAN networking and LTE networking Download PDFInfo
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- CN112135326A CN112135326A CN202010787451.XA CN202010787451A CN112135326A CN 112135326 A CN112135326 A CN 112135326A CN 202010787451 A CN202010787451 A CN 202010787451A CN 112135326 A CN112135326 A CN 112135326A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/14—Reselecting a network or an air interface
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
- H04W36/0085—Hand-off measurements
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
- H04W4/30—Services specially adapted for particular environments, situations or purposes
- H04W4/40—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P]
- H04W4/42—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P] for mass transport vehicles, e.g. buses, trains or aircraft
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
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- Aviation & Aerospace Engineering (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
The invention relates to a TAU switching method based on compatibility of WLAN networking and LTE networking, and belongs to the technical field of wireless communication. The invention comprises the following steps: switching process from LTE network to WLAN network: when the train enters the tail end covered by the LTE network, the TAU equipment detects that the train is about to enter an area without the LTE network coverage, and automatically switches from the LTE network to the WLAN network; switching process from WLAN network to LTE network: when the train only runs in the WLAN network coverage area, the TAU equipment continuously detects the transmission smoothness of the LTE network link and the WLAN network link, and automatically switches from the WLAN network to the LTE network after the fact that the LTE network is smooth is detected. The invention has the characteristic that the vehicle-mounted wireless terminal can realize the smooth switching between the WLAN and the LTE network systems under the condition of ensuring the normal work of the CBTC system.
Description
Technical Field
The invention relates to the technical field of wireless communication, in particular to a TAU switching method based on compatibility of WLAN networking and LTE networking.
Background
The CBTC system is a "communication based Train automatic Control system" (CBTC for short) generated by combining the computer technology, the communication technology, and the automatic Control technology. The CBTC system has the outstanding advantages of capability of realizing two-way communication between a vehicle and the ground, large transmission information quantity, high transmission speed and easiness in realizing a mobile automatic blocking system. Before the widespread use of LTE-M technology, WLAN was a commonly used vehicle-to-ground communication technology.
Since the radio administration committee approved industries such as rail transit to use 1785MHz-1805MHz as a dedicated frequency band. The LTE-M is more suitable for bearing the train-ground communication information of the rail transit signal system due to the advantages of wireless safety, high-speed mobility, difficulty in interference of a special frequency band and the like. The use of WLAN in metro signal systems is gradually being replaced by LTE.
With the development of communication technology, the lines previously networked by using the WLAN technology face the problems of old equipment halt, subsequent incapability of providing compatible products, more and more interference of co-channel interference sources on the WLAN system, train-ground communication interruption and train EB. Therefore, the former lines using WLAN networking tend to face the technical transformation of the train-ground wireless network and the construction of extension lines.
Therefore, it is necessary to design a switching method compatible with LTE and WLAN for the CBTC signaling system of urban rail transit.
Disclosure of Invention
The invention provides a TAU switching method based on compatibility of WLAN networking and LTE networking, which can enable a vehicle-mounted wireless terminal to realize smooth switching between two network systems of WLAN and LTE under the condition of ensuring normal work of a CBTC system, in order to overcome the problem that the vehicle-mounted wireless terminal cannot realize smooth switching between the two network systems under the condition that the existing line uses the WLAN and an extension line uses LTE to form a vehicle-ground communication network in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
the TAU switching method based on the compatibility of WLAN networking and LTE networking comprises TAU equipment; also comprises the following steps:
switching process from LTE network to WLAN network:
when the train enters the tail end covered by the LTE network, the TAU equipment detects that the train is about to enter an area without the LTE network coverage, and automatically switches from the LTE network to the WLAN network;
switching process from WLAN network to LTE network:
when the train only runs in the WLAN network coverage area, the TAU equipment continuously detects the transmission smoothness of the LTE network link and the WLAN network link, and automatically switches from the WLAN network to the LTE network after the fact that the LTE network is smooth is detected.
The TAU equipment in the invention is a vehicle-mounted access unit.
Optionally, the TAU device includes an uplink router and a downlink router:
optionally, the handover process from the LTE network to the WLAN network further includes the following steps;
after the TAU equipment is switched to the WLAN network, the LTE transmission link BFD detection response is automatically closed, and the WLAN transmission link BFD detection response is started;
and a downlink router in the TAU equipment receives the BFD detection response message in the WLAN, automatically adds the WLAN transmission link route, and automatically down the LTE network transmission link route when the BFD detection response in the LTE network transmission link is overtime.
Optionally, after detecting that the LTE network is unblocked, automatically switching from the WLAN network to the LTE network includes:
the train preferentially uses the LTE network to carry the service for information transmission, and the downlink route selector in the TAU equipment automatically adds the transmission route of the downlink LTE link after receiving the reachable LTE link.
Optionally, the handover process from the WLAN network to the LTE network further includes the following steps:
after an uplink route selector in the TAU equipment selects an LTE link as a transmission channel, the uplink route selector can close the BFD link detection message response of a downlink route selector of a WLAN network transmission link, the BFD detection response of the downlink route selector on the WLAN network transmission channel is overtime, and the downlink route selector automatically down drops the WLAN transmission channel route.
Optionally, a network overlapping coverage area is arranged between the LTE network and the WLAN network, and the length of the network overlapping coverage area is greater than 200 meters. In order to ensure a smooth handover, the coverage overlap region needs to be more than 200 meters considering the time from TAU network access to normal data transmission and the time from MR network access to normal data transmission.
Optionally, in the network switching process, the uplink router serves as a main router, a preferred WLAN network or LTE network is determined to serve as a main transmission link according to preset information, and the remaining transmission link automatically closes the BFD detection response of the downlink router; meanwhile, the downlink route selector automatically updates the transmission route according to the BFD detection message response condition, and realizes the same transmission path as the uplink route selector.
Optionally, the end of the LTE network coverage includes a last cell covered by the LTE network.
Optionally, before the handover process from the LTE network to the WLAN network and the handover process from the WLAN network to the LTE network, the method further includes the following steps:
establishing two IP intercommunication routes between the downlink route selector and the uplink route selector;
the downlink route selector and the uplink route selector establish two GRE tunnels based on the two IP intercommunication routes for carrying service to transmit information.
Therefore, the invention has the following beneficial effects: (1) the transmission link switching of the train in the ATO mode does not affect the running of the train, and the normal running of a CBTC system is ensured; (2) the invention can be used for a line using a WLAN system, and the extension line uses an LTE system; and under the scene that the WLAN system is transformed into the LTE system by the old line segmentation, the signal system does not degrade the operation.
Drawings
FIG. 1 is a flow chart of the present invention;
fig. 2 is a schematic diagram of a WLAN network-LTE network-WLAN network vehicle-ground wireless communication system in the present invention.
Detailed Description
The invention is further described with reference to the following detailed description and accompanying drawings:
example 1:
fig. 1 shows a TAU handover method based on compatibility between WLAN networking and LTE networking, which includes TAU equipment; also comprises the following steps:
when the train enters the last cell covered by the LTE network, the TAU equipment detects that the train is about to enter an area without the LTE network coverage, and automatically switches from the LTE network to the WLAN network;
when the train only runs in the WLAN network coverage area, the TAU equipment continuously detects the transmission smoothness of the LTE network link and the WLAN network link, and automatically switches from the WLAN network to the LTE network after the fact that the LTE network is smooth is detected.
Specifically, the TAU device includes an upstream router and a downstream router.
Specifically, before the handover process from the LTE network to the WLAN network and the handover process from the WLAN network to the LTE network, the method further includes the following steps:
establishing two IP intercommunication routes between the downlink route selector and the uplink route selector;
the downlink route selector and the uplink route selector establish two GRE tunnels based on the two IP intercommunication routes for carrying service to transmit information.
Optionally, in the handover process from the LTE network to the WLAN network, the following steps are further included;
after the TAU equipment is switched to the WLAN network, the LTE transmission link BFD detection response is automatically closed, and the WLAN transmission link BFD detection response is started;
and a downlink router in the TAU equipment receives the BFD detection response message in the WLAN, automatically adds the WLAN transmission link route, and automatically down the LTE network transmission link route when the BFD detection response in the LTE network transmission link is overtime.
In the switching process from the WLAN network to the LTE network, automatically switching from the WLAN network to the LTE network after the LTE network is detected to be unblocked comprises the following steps:
the train preferentially uses the LTE network to carry the service for information transmission, and the downlink route selector in the TAU equipment automatically adds the transmission route of the downlink LTE link after receiving the reachable LTE link.
Optionally, in the handover process from the WLAN network to the LTE network, the method further includes the following steps:
after an uplink route selector in the TAU equipment selects an LTE link as a transmission channel, the uplink route selector can close the BFD link detection message response of a downlink route selector of a WLAN network transmission link, the BFD detection response of the downlink route selector on the WLAN network transmission channel is overtime, and the downlink route selector automatically down drops the WLAN transmission channel route.
Optionally, a network overlapping coverage area is arranged between the LTE network and the WLAN network, and the length of the network overlapping coverage area is greater than 200 meters. In order to ensure a smooth handover, the coverage overlap region needs to be more than 200 meters considering the time from TAU network access to normal data transmission and the time from MR network access to normal data transmission.
In the switching process of the WLAN network and the LTE network, an uplink route selector serves as a main route selector, the preferred WLAN network or the LTE network is judged to serve as a main transmission link according to preset information, and the remaining transmission link automatically closes the BFD detection response of the downlink route selector; meanwhile, the downlink route selector automatically updates the transmission route according to the BFD detection message response condition, and realizes the same transmission path as the uplink route selector. In addition, in the specific implementation, the uplink router configuration actively detects the LTE network link status, and preferentially uses the LTE network bearer service.
Example 2:
as shown in fig. 2, a schematic diagram of a vehicle-ground wireless communication system for implementing WLAN network-LTE network-WLAN network handover is shown. As shown in the figure, the system includes two switches, a wireless controller, a baseband processing unit BBU, 4 radio remote units RRU, a 4G network core EPC, and two combiners. The system is additionally provided with an exchanger on the basis of the original communication system, and the exchanger is used for connecting wireless signal access points of two networks and is externally connected with a wireless controller for control. The newly added exchanger is electrically connected with the original exchanger. The original switch and the 4G network core EPC are connected and communicated through a wired ring network. The base band processing unit BBU is connected with the 4 RRUs through optical fibers, and the two RRUs with the same type are integrated through a combiner to realize network coverage.
Under the system shown in the figure, the network switching process of the train is as follows:
when the initial train only runs in a WLAN network coverage area, the TAU equipment continuously detects the transmission smoothness of an LTE network link and a WLAN network link, and automatically switches from the WLAN network to the LTE network after the smoothness of the LTE network is detected;
when the train enters the last cell covered by the LTE network, the TAU equipment detects that the train is about to enter an area without the LTE network coverage, and automatically switches from the LTE network to the WLAN network. The specific handover procedure is the same as in example 1.
The invention realizes that the vehicle-mounted wireless terminal can realize the smooth switching between the WLAN and LTE network systems under the condition of ensuring the normal work of the CBTC system based on the vehicle-ground wireless communication system formed by the WLAN networking of the old line and the LTE networking of the extended line.
The invention can be used for a line using a WLAN system, and an extension line uses a line using an LTE system; and the method can also ensure that the signal system does not degrade operation under the scene that the old line segments modify the WLAN system into the LTE system.
It should be understood that this example is for illustrative purposes only and is not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
Claims (9)
1. The TAU switching method based on compatibility of WLAN networking and LTE networking is characterized by comprising TAU equipment; also comprises the following steps:
switching process from LTE network to WLAN network:
when the train enters the tail end covered by the LTE network, the TAU equipment detects that the train is about to enter an area without the LTE network coverage, and automatically switches from the LTE network to the WLAN network;
switching process from WLAN network to LTE network:
when the train only runs in the WLAN network coverage area, the TAU equipment continuously detects the transmission smoothness of the LTE network link and the WLAN network link, and automatically switches from the WLAN network to the LTE network after the fact that the LTE network is smooth is detected.
2. The TAU switching method compatible with the LTE networking based on the WLAN networking according to claim 1, wherein the TAU device comprises an uplink router and a downlink router.
3. The TAU handover method compatible with LTE networking based on WLAN networking according to claim 2, wherein the handover procedure from LTE network to WLAN network further comprises the following steps;
after the TAU equipment is switched to the WLAN network, the LTE transmission link BFD detection response is automatically closed, and the WLAN transmission link BFD detection response is started;
and a downlink router in the TAU equipment receives the BFD detection response message in the WLAN, automatically adds the WLAN transmission link route, and automatically down the LTE network transmission link route when the BFD detection response in the LTE network transmission link is overtime.
4. The TAU switching method based on compatibility of WLAN networking and LTE networking according to claim 2, wherein said automatically switching from WLAN to LTE network after detecting that LTE network is unblocked comprises:
the train preferentially uses the LTE network to carry the service for information transmission, and the downlink route selector in the TAU equipment automatically adds the transmission route of the downlink LTE link after receiving the reachable LTE link.
5. The TAU switching method based on compatibility of WLAN networking and LTE networking according to claim 4, wherein the switching process from WLAN network to LTE network further comprises the following steps:
after an uplink route selector in the TAU equipment selects an LTE link as a transmission channel, the uplink route selector can close the BFD link detection message response of a downlink route selector of a WLAN network transmission link, the BFD detection response of the downlink route selector on the WLAN network transmission channel is overtime, and the downlink route selector automatically down drops the WLAN transmission channel route.
6. The TAU switching method compatible with the LTE networking according to the claim 1, 2, 3, 4 or 5, wherein a network overlapping coverage area is arranged between the LTE network and the WLAN network, and the length of the network overlapping coverage area is more than 200 m.
7. The TAU switching method based on the compatibility of the WLAN networking and the LTE networking according to claim 2, wherein in the switching process of the WLAN network and the LTE network, the uplink router is used as a main router, the preferred WLAN network or the LTE network is judged to be used as a main transmission link according to preset information, and the remaining transmission link automatically closes the BFD detection response of the downlink router; meanwhile, the downlink route selector automatically updates the transmission route according to the BFD detection message response condition, and realizes the same transmission path as the uplink route selector.
8. The TAU switching method compatible with LTE networking based on WLAN networking according to claim 1 or 2 or 3, characterized in that the end of LTE network coverage comprises the last cell of LTE network coverage.
9. The TAU switching method compatible with the LTE networking based on the WLAN networking according to claim 2, wherein before the switching process from the LTE network to the WLAN network and the switching process from the WLAN network to the LTE network, the method further comprises the following steps:
establishing two IP intercommunication routes between the downlink route selector and the uplink route selector;
the downlink route selector and the uplink route selector establish two GRE tunnels based on the two IP intercommunication routes for carrying service to transmit information.
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| CN202010787451.XA CN112135326B (en) | 2020-08-07 | 2020-08-07 | TAU switching method based on compatibility of WLAN networking and LTE networking |
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| CN202010787451.XA CN112135326B (en) | 2020-08-07 | 2020-08-07 | TAU switching method based on compatibility of WLAN networking and LTE networking |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116156514A (en) * | 2023-01-18 | 2023-05-23 | 浙江众合科技股份有限公司 | Non-interference reconstruction method for vehicle-ground communication of signal system |
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