GB2391426A

GB2391426A - Alleviating network message congestion by using one of a plurality of subscriber identifier numbers associatied with one host

Info

Publication number: GB2391426A
Application number: GB0125416A
Authority: GB
Inventors: Jeffrey Wilson
Original assignee: Intellprop Ltd
Current assignee: Intellprop Ltd
Priority date: 2001-10-23
Filing date: 2001-10-23
Publication date: 2004-02-04
Also published as: GB0125416D0

Abstract

In a mobile telephone system, a routing information request signal (B) from another network is received in the home network (operator A's network). When the received routing information request signal (B) is determined to be associated with a message signal (A) received at the other network and intended for a host in the home network, a routing information response signal (C) is sent back to the other network allowing the message signal (D) to be directed to the intended host. The routing information response signal (D) includes one of a plurality of identifier numbers (IMSI numbers) all of which are associated with the host. Thus different message signals to the intended host may be assigned different subscriber identifier numbers of the plurality, thereby alleviating message signal congestion in the other network.

Description

l TELECOMMUNICATIONS SERVICES APPARATUS

INTRODUCTION

This ins ention pennits significantly increased throughput of Short Message transmissions frond foreign networks to SMS Hosts in the home network This is an important revenue-generating application for SMS. which is being used increasingly for applications such as voting and premium services Mans networks support attached equipments known as SMS Hosts which can 10 send and receive Short Messages SMS Hosts are usually third parts equipments attached be; communication links to the Short Message Service Centres (SMSCs) of a mobile telephone network. The SMS Hosts can receive messages from any mobile phone on any compatible network bit means of an MSISDhI nu;rnber. or number range.

so that the Host appears to the sending network and any intervening networks to 15 behave as a normal Mobile Station (MS) destination for a short message. When the message is received by the mobile telephone network. it is routed to its appropriate Host. rather than to a mobile Mans terri tories are served by multiple PLMNs For the purposes of 20 explanation in the following text Operator A is assumed to have an SMS Host. which in addition to being capable of sending Short Messages to. or receiving Short Messages from. the subscribers of Operator A. is also able to send Short Messages to.

or receive Short Messages from. subscribers of Operators B and C who operate PLMNs in the saline county. and also subscribers of operators in other countries 3 For an application such as voting whereby votes by SMS are solicited via a medium such as television. it will be normal for the Operator A to expect notes to be sent not only from users of its network. but also from users of other netv,-orls For example. in our hypothetical country with three mobile operators A. B and C of similar size. a national oting event hosted by one of the operators could expect around two thirds of 30 the v otes to arrive at its SMS Host from Operators B and C.

Here lies a problem for the operator as a result of the way- the GSM system Is specified. When a Short Message is sent to Operator A s SMS Host by a mobile subscriber of Operator B. the message first tray els to the SMSC of Operator B s network This SMSC determines the subsequent routing information by querying an HLR in Operator A s networl;. and then delivers the message. However for a voting application and for similar applications. Operator B s SMSC will receive very- many Short Messages for delivery to the same MSISDN destination number. The GSM specification mandates that an SMSC

shall not attempt to deliver a second Short Message to the same number until the previous 10 message has been acknowledged. For properlyimplemented SMSCs this typically- limits the throughput of messages to a given destination MSISDN to around one per second.

This leads to two problems. Firstly the burst high loading which can result from a Noting application can lead to a backlog of messages in Operator B s SMSC if 15 deliver' can only be effected at one per second. and this backlog can stress the limited resources of an SMSC and may affect other SMS traffic in Operator B s network.

Secondly-. if the number of messages sent is large compared to the duration of the event in seconds. then most of the messages still will not have been delivered after the event has finished. This makes interaction with the senders. e.g. for solicitation of a 20 second vote. impossible. and hence reduces possible revenues.

This invention provides a solution to this problem which can be implemented simply in Operator A s network. and allows the delivers rate of about one per second from any other operator s SMSC to be significantly speeded up. without requiring any 25 changes at all in the other operators nerw-orks.

PRIOR ART

The functionality and operation of Home Location Registers (HLRs) in modern mobile networks is well described by- the international standards. Although HLRs may 30 implement proprietary features. the signalling messages which are required to support short message reception and transmission are fulls defined. Hence also the signalling

traffic which results from particular patterns of short message traffic is also quantifiable. The use of SMS Hosts is also well known. SMS Hosts are usuall\ connected 5 to a mobile network via the Short Message Sersice Centre (SMSC). using one of a number of standard protocols. Many networks support the reception and transmission of large quantities of short messages b\ attached SMS Hosts.

It is also known that methods exist for accessing these SMS Hosts from other 10 networks. albeit with the throughput restrictions described above These methods overcome earlier addressing limitations by assigning the SMS Hosts a range of mobile telephone numbers so that messages can be addressed to them as though the, were mobile handsets. This permits access to the SMS Hosts from any mobile network 15 It is also known that HER functionality can be divided amongst multiple physical equipments. These equipments are norrnalls geographically diverse and phvsicall similar Signalling messages can be routed within a network using Signalling Transfer 70 Points (STPs). These have the capabilities to direct messages to preferred or secondary- destinations according to an addressing scheme which uses Global Titles.

The MSISDN of the destination mobile telephone or SMS Host has been used as the Global Title for routing Short Messages. BY manipulating the lookup tables within STPs it is possible to control the routing of signalling messages through a networks 2: STPs can also compensate for non availability of a signalling destination bar using secondary or tertiary routing addresses. Global titles can also be assigned to groups of equipments. with STPs used to distribute messages to that title amongst the equipments. 30 Additional equipments can be placed in a network to intercept certain types of signalling message in order to reduce the loading on the network s HLRs. Application UK 12294.1 describes such an application. and the same type of equipment and

techniques could be used together with the enhancement described be the present intention to provide the additional benefit of increased SMS throughput.

DESCRIPTION OF INVENTION

In some cases" an SMS Host attached to Operator A's networks can be responsible for massive levels of SMS traffic and this traffic tends to be peaky in nature. with much traffic arriving from other operators' SMSCs. Examples include subscriptions to football results serf ices and telex oting resulting from television programmes. The invention removes a major bottleneck in the deliver mechanism at 10 these other operators' SMSCs. Implementations of the invention could for example preferably be placed at network interconnect points of Operator A. so that traffic within Operator A's network is minimised.

Traffic Analysis 1: Figure I shows a block diagram of the network of Operator A. including its HLR and the paths of signalling messages invol:eci in delivering a Short Message from Operator B's network.

Figure 1 shows the network configuration prior to implementation of the invention. When a Short Message is sent from one of Operator B's subscribers to a 30 Host on Operator A's network. the message first arrives at an SMSC in Operator B's network. This SMSC then queries the HLR in Operator A's network using a --Send Routing Info for Short Message'' signalling message. It receives a Routing Info for Short Message'' response contair.ung both the IMSI of the destination MSISDN. and the required routing address. After delivering the messages a properly implemented - SMSC must -wait until the delivery has been acknowledged bythe SMS Host before sending another to the same SMS Host. This leads to the bottleneck at Operator B's SMSC. The bottleneck arises because all of the -Routing Info for Short Message'' responses -11 contain the same IMSI.

30 The ins ention described here works by- substt-uting this fixed IMSI by an IMSI chosen from a range of possible IMSIs. preferably by rotating through a range

s sequentially with each succeeding response sent In order to implement this in the home network. it is simply- necessary to allocate a range of IMSI values to each Host In order to properly implement the message serialisation according to the GSM spec. the SMSC must utilize the IMSI to determine that no deliveries are currently outstanding to the same Mobile Station (in this case. a list.) The SMSC should not use the MSISDN to perform this check since a single mobile station mat have several different MSISDNs but only ever one IMSI 10 Figure show-e the same scenario. but with the invention implemented A preferred embodiment of the invention works as follows: A short message is sent by a subscriber Operator B's network This is sent as a - MOforwardSM'' Mobile Originated Short Message to the Operator B's SMSC. This 1: SMSC then attempts to query Operator A's HLR in order to find the address to which it should send the Short Message. The -Send Routing Info for Short Message'' signalling message is directed to Operator A's HLR by using the!SISDN number as its Global Title. This message then arrives at the interconnect point at the boundary of Operator A's network Here the gateway DISC uses its Signalling Transfer Point (STP) functionality to 90 direct the message to an SMS Router. The SMS Router is programmed to forward all messages to the HLR except for -Send Routing Information for Short Message 'I For these specific messages only-. the signalling processor interprets the MSISDN number to determine whether it corresponds to one of Operator A's SMS Hosts This is easily achievable because the netrk's SMS Hosts will be allocated MSISDN numbers within I= A defined ranges Messages which are addressed to MSISDN numbers outside these ranges are routed directly to the existing HLRs as normal Hou-e7er. numbers which correspond to Operator A's SMS Hosts are responded to locally by the SMS Router using its oval internal look up tables For these messages. the SMS router sends a response back to Operator B's SMSC The key point of the ins ention is that the response message may 30 utilise one of a range of IMSI alues rather than Just a single -alue. By rotating through a range of IMSI values allocated to this MSISDN in the response message C'. the nnber of SMS deliveries which can be -in flight' simultaneously between Operator B's SMSC

and Operator A s SMS Host can be significantly increased. thereby reducing or removing the bottleneck at Operator B s SMSC.

No changes are required outside Operator A s network.

- The inention can be implemented as a vers lou COSt solution w-hich can be replicated easily around a network s interconnect points. Because the locations and hence the signalling addresses of the SMS Hosts do not change continually over time.

unlike those of mobile stations the implementation of the invention may utilise PROM 10 manors. The addresses of the SMS Hosts which are to be filtered by the grooming operation described ma! be hard coded into the programming of the machine.

Additional SMS Hosts brought on line after commissioning of an implementation of the invention will not have their addresses preprorarnmed into the 15 implementation. Therefore messages addressed to these new SMS Hosts mill not be filtered by- the invention. This is not a problem because all SMS Hosts will be programmed into the HLR. and these messages will be handled by; the HLR in the usual way. This reduces the need for configurability; and maintenance of the implementation to a minimum.

All network MSISDN numbers and their associated subscriber data including those MSISDNs assigned to SMS Hosts. are programmed as normal into the existing HLRs. This is necessary- for several reasons: 95 Messages to the SMS Hosts from the netuorlc s own subscribers will be handled by the existing HLRs. Al signalling messages cormected with SMS Hosts.

apart from the Send Routing Info for Short Message from other networks will be handled by the HLR in the normal we. This has the advantage that the invention requires minimal changes to the existing network. It also means that in the event of 30 non availability of the SMS router for ens reason. then the S[P functionality of the gateway MSC will pass all messages directly to the existing HLRs as before resulting in no loss of network functionality.

Effect of Host Unavailability In the event of unavailability of an SMS Host. then an SMSC will fail to 5 deliver a message to the desired SMS Host destination. When it detects that it has failed to deliver the message. it hill embark on a retry cycle and also send a message to the HLR indicating that there is a message waiting for this MSISDN. The HLR maintains a database of -message waiting data which contains a look-up table of MSISDNs and the SMSCs which are waiting to deliver messages to that number 10 When the MSISDN (in this case an SMS Host) becomes available again. the HLR will signal to all of those SMSCs that the! should re-attempt deliver. This mechanism is completers independent of the implementation of the present invention since none of the messages connected with message waiting data is intercepted or acted upon by the SMS Router. The only messages which are intercepted are Send Routing Info for 15 Short Message.

GLOSSARY

SMS Short Message Service of the GSM mobile telephone system PLAN Public Land Mobile Network SMS Host Equipment for sourcing and sinking Short Messages for specific applications SMS Router Equipment which embodies the intention and filters and responds to certain signalling messages.

HI R Home Location Register _

Claims

5 1. A telecommunications services apparatus for use with a mobile telephone so stern which has a home network with at least one host being connected to the home network. the apparatus comprising means for receiving a routing information request signal from another network. and determining means for determining when the received routing information request signal is associated 10 with a message signal received at the other network and intended for a host connected to the home network and. if so. being operable to send back a routing information response signal to the other network thereby allowing the message signal to be directed to the intended host. the routing information response signal including one of a pluralit of subscriber identifier numbers all 15 of which plurality are associated with the at least one host. such that different message signals to the intended host may be assigned different subscriber identifier numbers of the plurality thereby alleviating message signal congestion in the other network.

20 2. Apparatus according to claim 1 wherein the determining means includes a memory storing the plurality; of subscriber identifier numbers associated with the at least one host connected to the home network.

3. Apparatus according to claim 1 or claim 9. wherein the subscriber identifier 2 numbers are International Mobile Subscriber Identifier (IMSI) numbers associated Pith the at least one host connected to the home network.

Apparatus according to claim 3. wherein the IMSI numbers of the at least one host are allocated within a defined range.

is. Apparatus according to claim 4. wherein the IMSI numbers in the defined range are assigned in a rotating manner to successive message signals for the host or hosts.

6 Apparatms according to an! one of the preceding claims. wherein the home network includes a home location register. and Serum the determining means includes diverting means operable to divert the routing information request signal away from the home location register when the received routing information request signal is determined to be associated with a message signal 10 received at the other network and intended for a host connected to the home network. 7. Apparatus according to any; one of the preceding claims. wherein the message signal is a text message signal.

8. Apparatus according to any one of the preceding claims. wherein more than one host is connected to the home network. and wherein a subset of the plurality of subscriber identifier numbers is associated with each host.

20 9. A telecommunications services apparatus substantially as hereinbefore described with reference to and as illustrated in Figure 2 of the drawings.

Amendments to the claims ha ve been filed as follows 1 A telecommunications services apparatus for use with a mobile telephone system which has a home network with at least one host being connected to the 5 home network. the apparatus comprising means for receiving a routing information request signal from another network. and determining means for determining when the received routing information request signal is associated with a message signal received at the other network and intended for a host connected to the home network and. if so being operable to send back a 10 routing information response signal to the other network thereby allowing the message signal to be directed to the intended host. the routing information response signal including one of a plurality of subscriber identifier numbers all of which plurality are associated with the at least one host. such that different message signals to the intended host may be assigned different subscriber 1, identifier numbers of the plurality thereby alleviating message signal congestion in the other network Apparatus according to claim 1 wherein the determining means includes a memory storing the plurality- of subscriber identifier numbers associated with 20 the at least one host connected to the home ne twork 3. Apparatus according to claim 1 or claim wherein the subscriber identifier numbers are International Mobile Subscriber Identifier (IMSI) numbers associated with the at least one host connected to the home network 4 Apparatus according to claim 3. wherein the TMSI numbers of the at least one host are allocated within a defined range Apparatus according to claim 4 wherein the IMSI numbers in the defined 30 range are assigned in a rotating manner to successive message signals for the host or hosts

it' 6 Apparatus according to any one of the preceding claims. wherein the home network includes a home location register. and wherein the determining means includes diverting means operable to divert the routing information request signal au-as from the home location register when the received routing information request signal is determined to be associated with a message signal received at the other network and intended for a host connected to the home network. 7 Apparatus according to any one of the preceding claims. wherein the message I O signal is a text message signal 8 Apparatus according to any one of the preceding claims. wherein more than one host is connected to the home network. and wherein a subset of the pluralit of subscriber identifier numbers is associated with each host 9 Apparatus according to ens one of claims 1 to 7 wherein more than one host is connected to the home network. and wherein the plurality of subscriber identifier numbers is shared amongst all the hosts 90 10 A telecommunications services apparatus substantially as hereinbefore described with reference to and as illustrated in Figure 2 of the drawings