Flow control of short message service messages in a cellular telephone network

(54) Title: PROCESS AND SYSTEM TO CONTROL THE FLOW OF SHORT MESSAGE SERVICE MESSAGES ALONG A RADIO LINK INTERFACE (30) Unionist Priority: i8 / ú4 / i996 us03 / 634376 (71) Depositor (s): Telefonaktiebotaget LM Ericsson (SE) (72) Inventor (s): Ove Huít, Richard Brunner (74) Attorney: Morrrsen. Leonardos â Cia.

(86) International application: pct SE97 / 00624 of 14/0 * 1997 (87) International publication: wo 97/39593 of 23/10/1997 (57) Summary: process and system for controlling the FLOW OF MESSAGE MESSAGES FROM A SHORT MESSAGE ALONG A RADIO LINK INTERFACE Measurements (100) of the loading being carried in the control channel (33) of a radio link interface (26) of a cellular telephone network (10) and then processed to identify (108) a maximum short message service message length allowed for transmission on the control channel. Short message service messages with lengths shorter (114) than the maximum allowed are allowed for transmission (120) along the control channel. Any short message service message having an extension exceeding (122) the specified maximum extension, however, is refused authorization for transmission on the control channel. The refused messages are then saved (126) for transmission on the control channel at a later time, when the measured load allows, or transmitted (128) along the traffic channel portion (36) of the radio link interface.

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PROCESS AND SYSTEM TO CONTROL THE FLOW OF SHORT-MESSAGE SERVICE MESSAGES ALONG A RADIO LINK INTERFACE ”.

BACKGROUND OF THE INVENTION

Technical Field of the Invention

The present invention relates to cellular telephone networks and, in particular, cellular telephone networks supporting the sending of short message service messages.

Description of the Related Art

Many cellular telephone networks support the transmission of short message service (SMS) messages between short message entities (SívIE) including mobile stations and short message terminals. Such a network comprises the digital cellular network specified in TIA IS136. Short message service messages are typically transmitted along the control channel portion of the cellular radio link interface provided by the network between mobile stations and base stations. The control channel is, however, provided primarily for use in transmitting network operation control signals, and such signals have priority over the transmission of short message service messages. Therefore, approval for transmission must be requested and received before the control channel is used to transmit the short message service messages.

The space in the control channel for transmitting short message service messages is often limited. Consequently, a fixed limitation is typically placed on the extent of the short message service messages transmitted along the control channel. By limiting the length of the message, some control measure over the congestion of the control channel can be performed. In times when the control channel loading is reduced, however, the extension limitation unduly restricts the efficient use of the control channel to load short message service messages.

It is also recognized that the traffic channel portion of the cellular radio link interface provided between mobile stations and base stations comprises an alternative communications resource on the network for carrying short message service messages, especially those messages that are restricted in length from transmission along the control channel. However, traffic channels are the primary source of income for communications resources, and it is more beneficial for the service provider to use traffic channels to carry voice communications than short message service data communications. Consequently, it is preferred that short message service messages are restricted as far as possible to transmission along the control channel.

There is therefore a need for an improvement in the way of handling the flow of short message service message transmissions along the radio link interface of the cellular telephone network. Such improved processing should accommodate short message service messages of varying lengths while simultaneously favoring the use of the control channel opposite the traffic channels for the message transmission medium along the radio link interface.

SUMMARY OF THE INVENTION

Measurements of the communication load being processed by the control channel of a radio link interface of a cellular telephone network are made and then processed to determine the maximum extent of a short message service message allowed at that moment for transmission along the transmission channel. control. If a requested short message service message transmission has an extension that is shorter than the specified maximum extension, transmission over the radio link interface control channel is authorized. Short message service messages having an extension exceeding the specified maximum extension, however, are denied authorization for transmission on the control channel, and need to either be saved for transmission on the control channel at a later time, or transmitted over the portion of the traffic channel of the radio link interface.

An advantage provided by this short message service message processing procedure is that there is no limitation placed on the maximum allowed length of short message service messages. Instead, any short message service message extension is allowed, however the transmission of any excess long messages needs to wait for the reduced load times of the control channel. Another advantage is that the procedure promotes the use of the control channel instead of the traffic channels for short message service message transmissions along the radio link interface. Only those short message service messages having extensions that do not satisfy the control channel loading determination and analysis have refused immediate authorization for transmission along the control channel.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the process and apparatus of the present invention can be obtained by reference to the following Detailed Description, when considered in conjunction with the accompanying Drawings, in which:

FIGURE 1 is a block diagram of a cellular telephone network;

FIGURE 2 is a flowchart illustrating the operation of the cellular telephone network of FIGURE 1 to control the flow of messages from * · · &lt;· a · · ♦ · short message service along the radio link intertace; and

FIGURE 3 is a graph illustrating exemplary relationships between measured control channel loading and permitted short message service message length.

DETAILED DESCRIPTION OF THE DRAWINGS

Reference is now made to FIGURE 1, in which a block diagram of a cellular telephone network 10 is shown. Network 10 supports a short message service (SMS) for use by subscribers in conjunction with its cellular voice service. The purpose of the short message service is to provide a means to transfer text messages between short message entities (SME) 12 using the communications environment provided by the cellular telephone network 10.

The short message entities 12 participating in the short message service comprise short message terminals (SMT) 14 connected to the fixed telephone network 16 (comprising a public switched telephone network (PSTN) or other equivalent telephone network). Short message entities 12 further comprise mobile subscriber stations (MS) 18 operating within the cellular telephone network 10. Short message service messages must originate or end at one of the mobile subscriber stations 18.

A short message service center or message center (MC) 20 is connected to physical telephone network 16 and cellular telephone network 10. Message center 20 functions as a warehouse and advanced center for receiving and sending message service messages. short between short message entities 12. In those situations where sending a short message service message to a short message service entity 12 fails, the message is stored in message center 20, to be subsequently retrieved by the recipient of the short message entity in an instant later .

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The cellular telephone network 10 additionally includes several base stations 24 (only one of which is shown) to carry out radio frequency communications over a radio link 26 with mobile stations 18. Each base station 24 is connected via a switching center (MSC) 30 to the fixed telephone network 16. The mobile switching center 30 operates to control the operation of the base station 24, and maintain a recording (in its home location record 32 and visitor location record 34) of the operation parameters of the mobile station 18 and location within the network 10 The mobile switching center 30 additionally switches, with the fixed telephone network 16, those cellular telephone calls originated by or terminated at the mobile stations 18. With regard to the provision of short message services, the mobile switching center 30 is additionally connected to the message center 20.

While cellular telephone network 10 is illustrated as having only one base station 24, it will naturally be understood that such network 10 should typically include many more base stations, and that the display of only one base station should be considered as an illustration, rather than a limitation of the operation of the present invention. It will be further understood that cellular telephone networks such as network 10 typically include much more than a simple mobile station 18 operating within network 10 at any time. The display of only one mobile station 18 is therefore to be considered as an illustration rather than a limitation on the operation of the present invention. Finally, although only one mobile switching center 30 is shown to simplify the illustration, it will be understood that network 10 will typically include many mobile switching centers interconnected to each other (perhaps via fixed telephone network 16), with each mobile switching center being connected to several of the base stations 24.

The radio link interface 26 can be, or Multiple • 4 44 4 44444

Time Division Access (TDMA), or Multiple Code Division Access (CDMA) or other type of radio link interface that supports the transmission of short message service messages. Short message service message transmissions with respect to a TDMA type interface, for example, are specified in the TIA IS-136, and a CDMA type interface supporting short message services is specified in the TIA IS-95. Such a radio link interface 26 typically includes several traffic channels 36 used to carry voice communications and at least one control channel 38 used to carry the control signals (commands) that direct the operation of the system. Control signals include incoming call signals, outgoing call signals, message signals, message response signals, location record signals, voice channel assignments, maintenance instructions, and cell selection or feedback instructions. selection.

Short message service messages can be transmitted along the radio link interface 26 using either one of the selected traffic channels 36 or control channel 38. It is preferred, however, that as much short message service traffic as possible is routed along the control channel 38, so as not to negatively impact the availability of resources to generate communications income sources for the mobile station 18. The resources for generating a source of income comprise the various traffic channels 36.

The cellular telephone network 10 additionally includes a charge measurement device from the radio link interface 40. Device 40 is connected to the mobile switching center 30, and is operable in connection with base stations 24 to measure the communication load carried by the radio link interface 26. In particular, device 40 operates to measure the load on control channels 38. The loading of the measured control channel is reported back to the mobile switching center 30 and processed in a manner to be described in the control of the short message service message flow along the radio link interface 26.

Reference is now made to FIGURE 2 in which a flow chart is shown illustrating the operation of the cellular telephone network 10 to control the flow of short message service messages along the radio link interface 26. In step 100, network 10 measures the loading (1) in the control channel 38, of the radio link interface 26. A determination is then made in step 102 of whether a request for a short message service message transmission along the radio link interface has been made. If no request was made, the process resumes via mesh 104 to perform a control channel loading measurement again. If, instead, a request was made for transmission of a short message service message (branch 106), the load measurement is processed in step 108 to determine a maximum extent (L_m) allowed at that time for a short message service message transmission along control channel 38.

Reference is now made to FIGURE 3, in which a graph is shown illustrating an exemplary relationship 50 between the loading of the measured control channel (1) on the v-52 axis, and the maximum allowed short message service message length (L_m) on the x-axis, 54. The ratio 50 is used to make the processing determination of step 108. In general, it will be noted that the ratio is substantially inversely proportional in nature, in which the greater the measured load of the control channel (1 ), the shorter the maximum allowed short message service message length (L_m). The relationship 50 may comprise a continuous (or linear piecemeal) relationship 50 (1) in which each loading point of the measured control channel 1 is associated with a single maximum allowed short message service message extension (L_m).

Alternatively, the ratio 50 may comprise a stair step ratio 50 (2) in which a measured control channel load range 1 is associated with a single maximum allowed short message service message extension (L_m). It will, of course, be understood that other types of relationships 50 can be specified for use when making the determination of step 108, and that the relationships 50 (1) and 50 (2) of FIGURE 3 are illustrative, rather than restrictive, of the operation of the system.

Referring now to FIGURE 2 again, following the determination of step 108 of the maximum allowed short message service message extension (L_m), the request received for a short message service message transmission along the radio link interface 26 is processed in step 110 to identify an extension (L_r) of the short message service message requested for transmission. The length of the requested short message service message (L_r) is then compared to the maximum allowed short message service message extension (L_m) in decision step 112, to determine whether the requested extension exceeds the maximum extension. If the short message service messages have a requested extension (L_r) that does not exceed the maximum determined extent (L_m), branch 114, a test is then performed at decision step 116 to determine whether control channel 38 of radio link interface 26 has sufficient capacity. If there is sufficient capacity, branch 118, the short message service message is authorized for transmission along control channel 38 of the radio link interface, and is transmitted in step 120. If the short message service message has an extension requested (L_r) that exceeds the determined maximum extension (L_m), branch 122 or when there is insufficient capacity in the control channel 38, branch 124, the authorization for transmission along the control channel of the radio link interface 26 is refused. These short message service messages must then either be saved at · 4 step 126 for subsequent transmission along control channel 38 (at one point when the loading of the measured control channel (1) decreases sufficiently and / or the capacity available) or are alternatively transmitted along the traffic channel portion 36 of the radio link interface 26 in step 128.

Referring now to FIGURES 1-3, the operation of the present invention in exercising flow control over short message service message transmissions can be better understood by examining some specific examples. Initially consider a short message service message intended for sending to a mobile station 18. A communication request to send a point-to-point short message service (SMSDPP) is generated at the message center 20 and routed (according to the information stored in the home location record 32 and visitor location record 34) through the cellular network, until it reaches the mobile switching center 30 serving as base station 24 for the cell where the recipient's mobile station 18 is currently located. At that moment, a request is made from the network 10 to transmit the short message service message along the radio link interface 26 to the recipient's mobile station 18 (step 102), the message having a certain identified extension (L_r) (step 110). In the meantime, measurements of loading (1) on control channel 38 have been made continuously and / or periodically for the radio link interface 26 used by base station 24 to communicate with the recipient's mobile station (step 100) .

Sensitive to the request for transmission of the short message service message, a determination is made by the network 10 of the maximum allowed short message service message extension (L_m) for transmission along control channel 38 (step 108). For example, with specific reference to FIGURE 3, if the measured load (1) is “A”, * »♦ then the maximum allowed short message service message length (L_m) is “B” with respect to the 50 (2) ratio, and “C” with respect to the 50 (1) ratio. The maximum allowed short message service message length (L_m) is then compared to the extension (L_r) of the requested short message service message (step 112).

If the extension (L_r) of the requested short message service message is less than or equal to the maximum allowable length of the short message service message (L_m) (branch 114), and capacity on control channel 38 is available (branch 118), so the message is cleared and transmitted to mobile station 18 along control channel 38 of radio link interface 26 (step 120) . If, on the other hand, the extension (L_r) of the requested short message service message is greater than the maximum allowed length of the short message service message (L_m) (branch 122), or there is insufficient capacity (branch 124), then the message is not authorized and cannot be transmitted at that moment to the mobile station 18 along the control channel 38 of the radio link interface 26. At this point, the message is returned to the message center 20 for storage and subsequent transmission to the mobile station 18, when the measured load (1) on the control channel 38 of the radio link interface 26 allows that transmission extension (step 126). Alternatively, the message is transmitted to the mobile station 18 along one of the traffic channels 36 of the radio link interface 26 (step 128).

Then consider a short message service message originating at the mobile station 18 and destined for sending to another mobile station on the network 10 or to a short message terminal 14. The mobile station initiates a communication along the control channel 38 of the radio link interface 26 requesting authorization from network 10 to make a short message service message transmission (step 102).

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This request includes information regarding the extension (L_r) of the requested short message service message (step 110). In the meantime, load measurements (1) on control channel 38 have been made continuously and / or periodically for the radio link interface 26 used by base station 24 to communicate with the recipient's mobile station (step 100) .

Sensitive to the request for transmission of the short message service message, a determination is made by the network 10 of the maximum allowed short message service message extension (L_ni) for transmission along control channel 38 (step 108). For example, with specific reference to FIGURE 3, if the measured load (1) is “A”, then the maximum allowable short message service message length (L_m) is “B” with respect to the 50 (2) ratio, and “C” with respect to the 50 (1) ratio. The maximum allowed short message service message length (L_m) is then compared to the extension (L_r) of the requested short message service message (step 112).

If the extension (L_r) of the requested short message service message is less than or equal to the maximum allowable length of the short message service message (L_m) (branch 114), and capacity on control channel 38 is available (branch 118), so the message is authorized for transmission over the network. The mobile station 18 then generates a short message service origin communication that is transmitted along the control channel 38 of the radio link interface 26 (step 120). If, on the other hand, the extension (L_r) of the requested short message service message is greater than the maximum allowed length of the short message service message (L_m) (branch 122), or there is insufficient capacity (branch 124), then the message is not authorized for transmission by mobile station 18 at that time. One option at this point is for mobile station 18 to have saved the message for subsequent transmission when the measured load (1) on control channel 38 of the radio link interface 26 allows that transmission extension (step 126). Alternatively, the message is transmitted from the mobile station 18 along one of the traffic channels 36 of the radio link interface 26 (step 128).

When the transmission of the message is not authorized (branches 122 and 124) the determination to save the message for retransmission (step 126) or to transmit along the traffic channels (step 128) is made in view of the service provider's operating instructions of network 10 previously specified (that is, a stored network service or resource profile). These operating instructions can specify that all short message service messages must be transmitted along control channel 38 of the radio link interface 26. In such a case, the message is always saved for retransmission (step 126). In connection with the transmission along the traffic channels (step 128), on the other hand, the operating instructions may specify a certain percentage of use of the traffic channels for transmission of short message service messages, or an extension restriction for transmission of short message service messages along the control channel.

Although an embodiment of the process and apparatus of the present invention has been illustrated in the accompanying Drawings and described in the preceding Detailed Description, it will be understood that the invention is not limited to the described embodiment, but is capable of numerous rearrangements, modifications and replacements, without depart from the spirit of the invention, as established and defined by the following claims.