CN1228232A - Procedure to improve capacity of V5 interface in wireless local loop environment - Google Patents

Abstract

The present invention relates to a procedure for maximizing the available capacity of a V5 interface (1) in a wireless local loop environment, in which a terminal device (5) is connected via a radio link to a base station (4a, 4b, 4c) and further to an access node (2) and a telephone exchange (3). The procedure of the invention allows considerably more effective reservation and use of the time slots of the V5 interface than before because it achieves a significant reduction of abortive reservations of time slots.

Description

Method for improving the capacity of a V5 interface in a wireless local loop environment

The invention relates to a method for maximizing the available capacity of a V5 interface in a wireless local loop environment in which a terminal device is connected via a radio link to a base station and It is further connected to an access node and a telephone exchange.

In a wireless local loop (WLL), a terminal device is connected to an access node via a radio link. Between the terminal device and the access node there is a base station, and call signals received by the base station from the terminal device by radio communication are forwarded via the access node to the public telephone network or back. Connect the access node to the telephone exchange with the V5.1 or V5.2 protocol.

The open interfaces (V5.1 and V5.2). The V5 interfaces enable subscribers belonging to a physically separate local loop which may be a wired or a wireless network to be connected using the standard interface of a telephone exchange. A dynamic concentrator interface V5.2 consistent with the standards ETS 300 347-1 and 347-2 consists of one or more (1-16) PCM (Pulse Code Modulation, pulse code modulation) cables. A PCM cable comprises a total of 32 channels, each of which has a transfer rate of 64 kbit/s, ie a total of 2048 kbit/s. The V5.2 interface supports analog telephones such as those used in the public telephone network, digital users of basic and system users such as ISDN (Integrated Services Digital Network, Integrated Services Digital Network), and other analog telephones based on semi-fixed connections. or digital terminal equipment.

In a prior art system, the telephone exchange had no way of determining whether a terminal device was accessible. To set up a call to a terminal, the call control system of the telephone exchange reserves a time slot in the V5 interface and notifies the access node of the call. The access node reserves resources for the call until the radio network control system declares the terminal device to be inaccessible. On the basis of this announcement, the access node releases the resources it has reserved and informs the telephone exchange of the unsuccessful call setup, on this basis the telephone exchange releases the reserved time slot of the V5 interface so that it can serve used by other users.

The problem with the method described above is that this involves unnecessary conservation of local loop capacity when call signals are transferred from the telephone exchange via a centralized access node to a closed terminal device. Especially in the V5 interface between the telephone exchange and the access node, such a call setup does not purposely occupy a time slot or time slots, since only in the access node is it possible to obtain information regarding the inaccessibility of the terminal device Information.

The object of the present invention is to eliminate the above-mentioned problems. A particular object of the invention is to create a method that allows a more efficient utilization of the available capacity of a V5 interface.

For the features which characterize the invention, please refer to the claims of the present application.

In the method of the invention, at least one of the time slots of the V5 interface is reserved for calls from the telephone exchange to terminal devices in order to maximize the available capacity of a V5 interface in a wireless local loop environment. The available capacity is the maximum capacity of the V5 interface, which means a certain number of time slots. The local loop environment includes an access node connected to a telephone exchange through a V5 interface, and a base station in communication with an access node and for transferring call signals between the access node and terminal devices.

In the method according to the invention, the accessibility of the terminals is monitored in the telephone exchange and a call to an inaccessible terminal cannot be established in the telephone exchange. This makes it possible to avoid useless reservations of time slots in a situation where it has proven that the terminal device is switched off and cannot receive calls. A terminal device is accessible when calls can be forwarded to it. Monitoring is based on the transfer of status data of the access port to the telephone exchange, which data is retained in the access node and indicates the accessibility of the terminal device connected to the access port. The status data of the access port are updated in the telephone exchange, preferably at the same time as when the status data of the access port are updated in the access node. According to the V5 proposals, the maintenance and updating of the status data of the access ports is carried out with the control protocol. The status of an access port can be either "operational" or "locked", ie, accessible or inaccessible. Further, when the radio link between the base station and the terminal device is cut off, i.e. when the terminal device is outside the coverage area of the base station or when the radio link is cut off for other reasons, the access The state data of the port is updated to the locked state. The call control system can then immediately release a time slot that might have been reserved for a terminal device, ie if the terminal device was active on a call when the radio link was cut off, it might have been reserved for an end-capable device.

In a preferred embodiment, through the IMSI (attach) and IMSI withdrawal (IMSI, International Mobile Subscriber Identify, International Mobile Subscriber Identity) functions performed by the terminal device, the information related to the accessibility of the terminal device is transmitted. Information, such functions are described in the standards of the ETS 300 530 series. When the power is turned on in the terminal device, the IMSI plus function is started, which actually corresponds to a standard terminal device location update procedure. Data indicating that a terminal device is operational is typically stored in the access node in binary form. The IMSI revoke function is implemented when power is cut off from the terminal device. In this case, corresponding status data are also stored in the access node. In the access node, the state of the terminal device is indicated by the state data of the access port.

When compared with the prior art, the invention has the advantage that it makes it possible to reduce the load on the call control resources both in the local telephone exchange and in the access node. Further, the invention makes it possible to avoid unnecessary reservations of time slots of the V5 interface, thereby making more time slots available for other calls to be transferred. A further advantage of the present invention is the ability to better monitor a terminal device's status data with IMSI add and drop functions.

In the following, the invention will be described in detail with the help of a preferred embodiment, according to which a wireless local loop environment is described, by referring to the accompanying drawings.

The wireless local loop system shown in the figure comprises an access node 2 . The access node 2 acts as a central element between a telephone exchange 3 and a terminal 5 , connecting subscribers to the telephone exchange 3 . The access node 2 is connected through a V5.2 interface 1 comprising 1-16 PCM cables (2Mbit/s) and the exchange terminal (ET) (not shown in the figure) of the telephone exchange 3, and the terminal exchange office has V5 interface needs of functions. However, the system represented by the figure comprises a number of base stations 4a, 4b and 4c, each of which has a given coverage area. In the system represented by the figure, in order to establish a connection between a terminal device and a telephone exchange, signals are transmitted between the base station 4a and the terminal device 5 by radio communication, and further signals are transmitted from the base station by wired connections to the access node 2, and from the access node to the telephone exchange via the V5 interface 1.

With further reference to the figure, when the terminal device 5 is powered on, an IMSI add function is implemented consistent with the recommendations above. By this action, the terminal device 5 informs the network that it is active so that calls destined for the terminal device can be routed to the terminal device. At the access node 2, the status data for the access port corresponding to the terminal device 5 is updated to the value "operating". At the same time, in the telephone exchange 3, with the control protocol of the V5 interface 1, by updating the user data stored in the telephone exchange for the V5 interface used by the access port, the state data of the access port is also updated.

When the power supply from an active terminal 5 is switched off, the terminal performs an IMSI deactivation function, for which the terminal does not expect an acknowledgment from the base station. By this action, the terminal device declares that it is not in operation, in other words, that the terminal device is not accessible, which means that no calls can be delivered to the terminal device. The status data for the access port associated with the terminal device is now updated to the value "locked". At the same time, in the telephone exchange 3, with the control protocol of the V5 interface, by updating the user data stored in the telephone exchange for the V5 interface used by the access port, the state data of the access port is also updated.

Further, when a call is set up, a check can be carried out in the telephone exchange first by reading the status data of the access port for the terminal device in question to determine whether the called terminal device is in the operating state. In this way, invalid reservations of time slots in the V5 interface 1 between the access node 2 and the telephone exchange are avoided.

The invention is not limited to the embodiments presented above, but many variations are possible within the framework of the inventive idea described by the claims.

Claims (9)

1. be used for making the active volume of a V5 interface (1) reach maximum method at a wireless local loop environment, this wireless local loop environment comprises an access node (2), access node (2) is connected to a telephone exchange (3) and base station (4a by the V5 interface, 4b, 4c), base station (4a, 4b, 4c) be used between access node and terminal installation (5), transmitting all signals, be at least all callings from the telephone exchange to the terminal installation in the method and be retained in a time slot in the V5 interface, be characterised in that the accessibility to terminal installation monitors in telephone exchange; With in telephone exchange, forbid a calling to a terminal installation that can not insert.

2. the method described in claim 1 is characterised in that the status data of access interface of accessibility that indication is connected to the terminal installation (5) of an access interface is sent to telephone exchange (3).

3. the method described in claim 2 is characterised in that when upgrading the status data of access interface in access node (2), and the status data of access interface is sent to telephone exchange (3).

4. as the method described in the claim 1 to 3 any one, it is characterized in that upgrading, the status data of access interface is sent to telephone exchange (3) by the user data that is stored in the telephone exchange to V5 interface (1).

5. as the method described in the claim 1 to 4 any one, be characterised in that

When terminal installation (5) energized, carry out an IMSI by terminal installation (5) and add function;

Add at IMSI on the basis of function that will be updated to " operation " for the status data of the access interface of terminal installation, the indicating terminal device can insert; With

The status data of access interface is sent to telephone exchange (3).

6. as the method described in the claim 1 to 4 any one, be characterised in that

When terminal installation (5) when cutting off the electricity supply, carry out an IMSI by terminal installation (5) and cancel function;

Cancel at IMSI on the basis of function, will be updated to " locking " for the status data of the access interface of terminal installation, the indicating terminal device can not insert; With

The status data of access interface is sent to telephone exchange (3).

7. as the method described in the claim 1 to 6 any one, be characterised in that when the radio link between base station (4) and terminal installation (5) is cut off, the status data of access interface is updated to " locking ".

8. as the method described in the claim 1 to 7 any one, be characterised in that, the status data of access interface is sent to telephone exchange (3) by control protocol.

9. as the method described in the claim 1 to 8 any one, be characterised in that on the basis of the user data of V5 interface the state to terminal installation (5) monitors in telephone exchange.

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