KR20000020658A - Method for setting call in cellular system - Google Patents

Abstract

PURPOSE: A method is provided to set up a calling party and a called party in a cellular communication system, using a CDMA(Code Division Multiple Access) technic. CONSTITUTION: When a mobile phone sends a calling answering message to a base station, the base station requires a source assignment to a mobile switching center(MSC), and sends an ACH(Access Channel Element) to the mobile phone. The mobile phone receives the ACH from the base station, and starts a second timer. When the MSC sends a channel assignment message to the base station, the base station sends the channel assignment message to the mobile phone, starts a first timer. The base station stores related information to the mobile phone. The base station sends a Null message informing that a traffic channel is assigned to the mobile phone. When the Null message arrives from the base station before the first timer expires normally, the mobile phone sends an obtained message to the base station. When the obtained message arrives before the second timer expires normally, the base station performs conversion with the mobile phone. If the obtained message does not arrive until the first timer expires normally, the base station searches the stored information of the mobile phone, retransmits the channel assignment message to the mobile phone, and starts the first timer. If the Null traffic message does not arrive until the second timer expires normally, the mobile phone releases the call.

Description

How to set up a call on a cellular system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellular system, and in particular, establishes a calling party and a called party in a cellular mobile communication system using a code division multiple access (CDMA) technique. It is about a method of (Setup).

The cellular mobile telecommunication system divides an entire coverage area into a plurality of base station areas, constitutes cells, which are small service areas, and centrally controls such base stations to a mobile switching center. Allows you to continue the call while moving from cell to cell.

1 shows a schematic diagram of a typical cellular system. As shown, a base station (BS) 20, 30, 40 providing a mobile communication service to a mobile telephone (MT) 10, and a plurality of base stations are publicly available. A Switched Telephone Network (PSTN) 60 or a Mobile Switching Center (MSC) 50 that connects to another base station.

In the cellular system configured as described above, a link directed from the base station in the direction of the mobile phone is called a forward link, and a link directed from the mobile phone in the direction of the base station is called a reverse link. Base stations supporting code division multiple access techniques use multiple channels. The forward channel includes a pilot channel, a synchronous channel, a paging channel, and a traffic channel, and the reverse channel includes an access channel and a traffic channel.

The base station uses a device called a channel element (CE) to operate the plurality of channels as described above. The base station has a plurality of channel elements, each channel element is operated in one of the several channels.

When the subscriber requests conversion, the mobile phone attempts to call setup for origination to the base station. 2 is a message flow diagram illustrating a call setup method according to the prior art.

The mobile telephone 10 transmits / calls a response message (s01) to a base station control processor (BCP) 24 of the base station through an access channel element (ACH) 22 of the base station 20. Send it. The base station control processor sends a resource allocation request message (s02) to the mobile switching center 50, while acknowledgment (Ack) for making / calling to the mobile phone via the paging channel element (PCH) 23. Send (s03)

The mobile switching center 50 searches for the information of the subscriber who has requested the resource allocation, and sends a channel assignment message s04 to the base station control processor 24 if the subscriber can receive normal service. The base station control processor sends a channel assignment message (s05) to the mobile phone via the paging channel element, and then selects one of a plurality of traffic channel elements (TCH) available at the base station, and selects the selected traffic channel element (21). C) sends a traffic channel assignment message s06, and the traffic channel element 21 sends a null traffic message s07 that does not contain data for the call to the mobile phone, informing that the traffic channel has been allocated.

When the mobile telephone receives the null traffic message s07, it sends a preamble s08 to the traffic channel element to indicate that it is ready to make a call. When the traffic channel element obtains the preamble s08 of the mobile telephone, the traffic channel element sends a mobile acquire message s09 to the base station control processor. The mobile phone and the base station then exchange voice data and make a call.

When the base station control processor sends a channel assignment message s06 to the mobile phone via the paging channel element, it starts a timer designated for a predetermined time (for example, 5 seconds). If the state of radio waves deteriorates rapidly according to the situation of the mobile telephone, the mobile telephone does not receive the channel assignment message s05 delivered by the paging channel element.

The mobile phone is then unable to turn on from the paging channel to the traffic channel, not receiving the null traffic message s08 of the traffic channel element, and the mobile phone failing to transmit the preamble s08 to the base station. The mobile phone's signal is not detected.

After the base station control processor sends the channel assignment message s05, if the mobile phone acquisition message s09 does not arrive until the timer expires normally, the base station control processor ignores all the steps that have been performed so far and releases it to the traffic channel element. Release the call by sending a (release) message (s10).

In this case, however, the base station requests call setup from a higher system, i.e., a mobile switching center or a public switched telephone network, and has already allocated resources. Therefore, even though the mobile phone has not received only the channel assignment message, it must remove all the resources already complexly allocated to the base station, the mobile switching center and the public switched telephone network. That is, the call establishment method according to the prior art causes a problem that the communication rate is lowered because it is not only very inefficient in terms of resource utilization but also fails to set up the call.

The present invention has been made to solve the problems of the prior art operating as described above, in case the mobile phone does not receive the channel assignment message of the base station due to the degradation of the forward link in the cellular system, it continues to try the call, It is an object of the present invention to provide a call setup method in a cellular system.

Another object of the present invention is to provide a method for establishing a call in a cellular system, in which the base station sends the channel assignment message again when the mobile telephone does not receive the channel assignment message of the base station.

Another method of the present invention is to provide a method for establishing a call in a cellular system, in which, when a base station sending a channel assignment message does not receive a preamble from a mobile phone, it maintains pre-allocated resources until the mobile phone releases the call. .

Other objects and advantages of the present invention will become more apparent from the following detailed description of the invention and the accompanying drawings.

1 shows a schematic diagram of a typical cellular system.

2 is a message flow diagram illustrating a call setup method according to the prior art.

<Explanation of symbols for main parts of the drawings>

10: mobile phone 20, 30, 40: base station

50: mobile switching center 60: public switched telephone network

A preferred embodiment of the call setup method in the cellular system according to the present invention, which is invented to achieve the above object, includes a mobile telephone for providing a mobile telephone service to a subscriber, a base station for transmitting and receiving wireless messages with the mobile telephone, and a base station. A cellular system comprising a mobile switching center for connecting a public switched telephone network or another mobile switching center,

A cellular system comprising a mobile telephone for providing a mobile communication service to a subscriber, a base station for transmitting and receiving wireless messages with the mobile telephone, and a mobile switching center for connecting the base station to a public switched telephone network or another mobile switching center.

The mobile telephone requesting a call to the base station;

Requesting a resource allocation from a base station which is requested to make a call to a mobile switching center;

Sending an acknowledgment to the mobile telephone by a base station allocated with a resource from the mobile switching center;

The mobile switching center sending a channel assignment message to the base station;

Sending, by the base station, a channel assignment message to the mobile telephone and starting a first timer;

Sending, by the base station, a null traffic message informing the mobile phone that a traffic channel has been allocated;

When the null traffic message arrives from the base station, the mobile telephone sending an acquisition message to the base station;

If the acquisition message arrives from the mobile phone before the first timer expires normally, the base station making a call with the mobile phone; And

If the acquisition message does not arrive from the mobile phone until the first timer expires normally, the base station retransmits the channel assignment message to the mobile phone.

Another preferred embodiment of a call setup method in a cellular system according to the present invention comprises a mobile telephone providing a mobile communication service to a subscriber, a base station and a base station transmitting and receiving wireless messages with the mobile telephone to a public switched telephone network or another mobile switching center. A cellular system comprising a mobile switching center for connecting,

The mobile telephone requesting a call to the base station;

Sending a base station acknowledgment to the mobile phone by a base station requested to make a call;

The acknowledgment of the mobile telephone starts a second timer;

If the null traffic message arrives from the base station before the second timer expires normally, the mobile telephone makes a call with the base station; And

If the null traffic message does not arrive from the base station until the second timer expires normally, the mobile phone further releases the call.

Another preferred embodiment of a call setup method in a cellular system according to the present invention comprises a mobile telephone providing a mobile communication service to a subscriber, a base station for transmitting and receiving wireless messages with the mobile telephone, and a base station to a public switched telephone network or another base station. A cellular system comprising a mobile switching center,

Requesting the call setup by the mobile telephone to the base station;

Sending a channel assignment message to a mobile telephone by a base station that is requested to set up a call; And

If the base station sending the channel assignment message does not detect the acquisition signal of the mobile telephone station within a certain time, the base station sends the channel assignment message back to the mobile telephone station.

Another preferred embodiment of a call setup method in a cellular system according to the present invention is a mobile telephone for providing a mobile communication service to a subscriber, a base station for transmitting and receiving wireless messages with the mobile telephone, and a base station to a public switched telephone network or another base station. A cellular system comprising a mobile switching center for connecting,

Requesting the call setup by the mobile telephone to the base station;

Requesting resource allocation from a base station, which has been requested to set up a call, to a mobile switching center;

Sending an acknowledgment to the mobile telephone by a base station that is requested to establish a call;

Allocating a channel to a base station by a mobile switching center that is requested to allocate resources;

Sending a channel assignment message to the mobile telephone by the base station assigned the channel; And

If the base station sending the channel assignment message does not detect the acquisition signal of the mobile telephone station within the first time, maintaining mobile phone related resources connected to the base station and the mobile switching center.

In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

3 shows a configuration of a cellular system to which the present invention is applied. As shown, the mobile phone 10 is connected to the channel elements of the base station 20 via a wireless link. The control processor 24 of the base station transmits and receives call data such as voice and the like through the traffic channel element 21, receives a communication control message of the mobile phone through the access channel element 22, and the paging channel element ( 23) send a communication control message to the mobile telephone.

The mobile telephone 10 sends an origination / call response message for call setup to the base station 20 and then starts a second timer designated for a predetermined time (eg 12 seconds) upon receiving an acknowledgment. The mobile phone waits for the channel assignment message of the base station until the second timer expires normally. If the call does not begin with the base station until the second timer expires normally, the mobile phone releases the call. Therefore, the present invention provides a method for transmitting the channel assignment message again before the second timer of the mobile phone normally expires.

When the base station sends a channel assignment message to the mobile phone, it stores the same message in memory. If the mobile phone does not receive the base station's channel assignment message due to degradation of the forward link, the base station sends back the stored channel assignment message to the mobile phone. The base station starts a first timer when sending a channel assignment message. If the preamble is not received from the mobile phone until the first timer expires normally, the base station sends the channel assignment message again. When the state of the mobile phone improves, the mobile phone receives a channel assignment message and transmits a preamble to the base station. The base station then normally talks with the mobile phone.

4 is a flowchart illustrating an embodiment of a call setup method according to the present invention. Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention.

If the calling subscriber requests the call, the mobile telephone 10 sends a call / call response message to the base station control processor (BCP) 24 via the access channel element (ACH) 22 of the base station 20 in step s110. Send it. In step s120, the base station control processor requests resource allocation from the mobile switching center 50, and at the same time, in step s130, the base station acknowledgment (BS) is transmitted to the mobile telephone through the paging channel element (PCH) 23. Send Ack). At this time, the mobile telephone receives an acknowledgment from the paging channel element of the base station and starts the second timer.

The mobile switching center 50, which is requested to allocate resources for calling, searches for information of the calling subscriber, and if the subscriber can receive normal service, allows the base station control processor to allocate a channel, and the base station control processor at step S140. A channel assignment message is sent to the mobile phone via the paging channel element. However, if the forward wireless environment of the mobile phone degrades, the mobile phone does not receive channel assignment messages and thus cannot switch channels to traffic channels. Therefore, the base station control processor sends a channel assignment message in step s140 for the case of retransmitting the channel assignment message, while starting the first timer in step s150 and storing information related to the mobile phone.

After sending the channel assignment message to the mobile phone, the base station control processor selects an available traffic channel element (TCH) and sends a null traffic message to the mobile phone via the traffic channel element at step s160, indicating that the traffic channel has been allocated. Inform. When the mobile phone receives a null traffic message through the traffic channel element, the mobile phone responds with a preamble through the traffic channel element, and the received traffic channel element transmits an acquisition message to the base station control processor. When the base station control processor receives the acquisition message in step S170, the base station performs a call with the mobile phone in step S210.

However, if the mobile phone does not receive the channel assignment message sent in step s140 due to the deterioration of the wireless environment, the mobile phone cannot receive the null traffic message, which is also a response to the null traffic message to the traffic channel element of the base station. Can't send preamble

In step s180, if the mobile phone acquisition message is not received from the traffic channel element until the first timer expires normally, the base station control processor retrieves the information of the mobile phone previously stored in step s190 and based on the retrieved information. The channel assignment message is generated, and the channel assignment message is retransmitted to the mobile phone in step S200.

If the wireless environment of the mobile phone is good, the mobile phone receives the retransmitted channel assignment message and switches from the paging channel to the traffic channel. The base station control processor retransmitting the channel assignment message selects one of a plurality of traffic channel elements (TCH) and sends a traffic channel assignment message to the selected traffic channel element. The traffic channel element sends a null traffic message to the mobile phone.

The mobile phone then sends a preamble to the traffic channel element indicating that it is ready to make a call, and the traffic channel element sends a mobile phone acquisition message to the base station control processor. The mobile phone and the base station then make a call.

The mobile phone starts the second timer when it receives an acknowledgment from the base station (s130), and automatically releases the call if it does not receive a null traffic message from the base station until the second timer normally terminates, thereby preventing the occupancy of unnecessary resources.

In the call setup method according to the present invention operating as described above, the base station for transmitting the second channel assignment message to the mobile telephone in step s210 does not re-store the information of the mobile telephone. This is because it is unnecessary to retransmit the channel assignment message if the channel assignment message is lost twice in a row.

The present invention can be variously modified and can take various forms and only the specific embodiments thereof are described in the detailed description of the invention. It is to be understood, however, that the present invention is not limited to the specific forms mentioned in the detailed description of the invention, but rather includes all modifications, equivalents, and substitutions within the spirit and scope of the invention as defined by the appended claims. It should be understood to do.

In the present invention operating as described above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

If the mobile phone does not receive a channel assignment message due to temporary deterioration of the wireless environment, the base station resends the channel assignment message before the mobile phone terminates its timer and releases the call. Therefore, it does not waste resources connected to base stations, mobile switching centers and public switched networks for call origination. That is, not only the resources between the base station and the mobile phone but also the resources inside the system can be utilized efficiently.

In addition, it is possible to exclude the case that the base station releases the call due to the temporary deterioration of the wireless environment, it is possible to improve the traffic rate of the call.

Claims (13)

A cellular system comprising a mobile telephone for providing a mobile communication service to a subscriber, a base station for transmitting and receiving wireless messages with the mobile telephone, and a mobile switching center for connecting the base station to a public switched telephone network or another mobile switching center. The mobile telephone requesting a call to the base station; Requesting a resource allocation from a base station which is requested to make a call to a mobile switching center; Sending an acknowledgment to the mobile telephone by a base station allocated with a resource from the mobile switching center; The mobile switching center sending a channel assignment message to the base station; Sending, by the base station, a channel assignment message to the mobile telephone and starting a first timer; Sending, by the base station, a null traffic message informing the mobile phone that a traffic channel has been allocated; When the null traffic message arrives from the base station, the mobile telephone sending an acquisition message to the base station; If the acquisition message arrives from the mobile phone before the first timer expires normally, the base station making a call with the mobile phone; And If the acquisition message does not arrive from the mobile phone until the first timer expires normally, the base station retransmits the channel assignment message to the mobile phone. 2. The method of claim 1, wherein starting the first timer further comprises the base station starting the first timer and storing information related to the mobile phone. The method of claim 1, wherein the resending of the channel assignment message comprises re-transmitting the channel assignment message by searching for information related to a previously stored mobile phone. A cellular system comprising a mobile telephone for providing a mobile communication service to a subscriber, a base station for transmitting and receiving wireless messages with the mobile telephone, and a mobile switching center for connecting the base station to a public switched telephone network or another mobile switching center. The mobile telephone requesting a call to the base station; Sending a base station acknowledgment to the mobile phone by a base station requested to make a call; The acknowledgment of the mobile telephone starts a second timer; If the null traffic message arrives from the base station before the second timer expires normally, the mobile telephone makes a call with the base station; And If the null traffic message does not arrive from the base station until the second timer expires normally, the mobile phone further releases the call. A cellular system comprising a mobile telephone for providing a mobile communication service to a subscriber, a base station for transmitting and receiving wireless messages with the mobile telephone, and a mobile switching center for connecting the base station to a public switched telephone network or another base station. Requesting the call setup by the mobile telephone to the base station; Sending a channel assignment message to a mobile telephone by a base station that is requested to set up a call; And If the base station sending the channel assignment message does not detect the acquisition signal of the mobile telephone station within a certain time, the base station sends the channel assignment message back to the mobile telephone station. 6. The method of claim 5, wherein sending the channel assignment message comprises: Generating a channel assignment message using information related to the mobile telephone; Sending the generated channel assignment message to the mobile telephone; And And storing the information in a memory of a base station. 7. The method of claim 6, wherein sending the channel assignment message again comprises: Searching for information related to the stored mobile telephone; Regenerating a channel assignment message using the found information; And And sending the regenerated channel assignment message to the mobile telephone. A cellular system comprising a mobile telephone for providing a mobile communication service to a subscriber, a base station for transmitting and receiving wireless messages with the mobile telephone, and a mobile switching center for connecting the base station to a public switched telephone network or another base station. Requesting the call setup by the mobile telephone to the base station; Requesting resource allocation from a base station, which has been requested to set up a call, to a mobile switching center; Sending an acknowledgment to the mobile telephone by a base station that is requested to establish a call; Allocating a channel to a base station by a mobile switching center that is requested to allocate resources; Sending a channel assignment message to the mobile telephone by the base station assigned the channel; And If the base station sending the channel assignment message does not detect the acquisition signal of the mobile telephone station within the first time, maintaining the mobile telephone related resources connected to the base station and the mobile switching center. 9. The method of claim 8, wherein maintaining the mobile phone related resources includes: A method for establishing a call in a cellular system, wherein the mobile phone maintains mobile phone related resources until a second time after receiving an acknowledgment from the base station. 9. The method of claim 8, wherein maintaining the mobile phone related resources includes: If the base station sending the channel assignment message does not detect the acquisition signal of the mobile telephone station within the first time, the base station further sends the channel assignment message back to the mobile telephone. 9. The method of claim 8, wherein the base station sends a channel assignment message to the mobile telephone. And the base station sends a channel assignment message to the mobile telephone, and then stores information related to the mobile telephone in the base station's memory. 12. The method of claim 11, wherein the base station sends a channel assignment message to the mobile telephone. If the base station sending the channel assignment message does not detect the acquisition signal of the mobile telephone station within the first time, the base station further searches for information related to the previously stored mobile telephone. The method of claim 12, wherein the base station sends a channel assignment message to the mobile telephone, Using the information related to the discovered mobile telephone, the base station sends back a channel assignment message to the mobile telephone.