Data compression negotiation in a telecommunication system
23 claims: 3 independent, 20 dependent
- 1Pate ntti vaati m u kset 1. Menetelmä datayhteyden muodostamiseksi tietoliikennejärjestelmässä , joka käsittää vaiheet pystytetään ensimmäisen tietoliikenneverkon ensimmäisen laitteen 5 ja Verkkosovittimen välille ensimmäinen osayhteys, jossa käytetään virheenkorjausprotokollaa, pystytetään Verkkosovittimen ja toisen tietoliikenneverkon laitteen välille toinen osayhteys, jossa käytetään virheenkorjausprotokollaa, suoritetaan datakompressioneuvottelu kompressioparametrien 10 asettamiseksi, tunnettu siitä, että menetelmä lisäksi käsittää vaiheen viivästetään verkkosovittimessa nopeammin kättelevän osayhteyden virheenkorjausprotokollan pystytystä ja/tai datakompressioneuvottelua, kunnes hitaammin kättelevän osayhteyden virheenkorjausprotokollan muo15 dostus on saatettu loppuun ja datakompressioneuvottelu voitu aloittaa.
- 2Patenttivaatimuksen 1 mukainen menetelmä, tunnettu siitä, että vastaanotetaan nopealta osayhteydeltä datakompressioneuvottelupyyntö ja ensimmäiset kompressioparametrit verkkosovittimeen, 20 tallennetaan ensimmäiset kompressioparametrit verkkosovittimessa, odotetaan datakompressioneuvottelupyyntöä ja toisia kompressioparametreja hitaammin kättelevältä osayhteydeltä, vastaanotetaan verkkosovittimeen toisen osapuolen toinen data25 kompressioneuvottelupyyntö ja toiset kompressioparametrit, johdetaan ensimmäisistä ja toisista kompressioparametreista molemmille osapuolille sopivat kompressioparametrit, lähetetään mainitut johdetut kompressioparametrit neuvotteluvastauksena ensimmäiselle ja toiselle osayhteydelle.. 30
- 3Patenttivaatimuksen 1 mukainen menetelmä, tunnettu siitä, että viivästetään nopeammin kättelevän osayhteyden virheenkorjausprotokollan muodostamista, pystytetään hitaammin kättelevän osayhteyden virheenkorjausprotokolla, vastaanotetaan datakompressioneuvottelupyyntö ja kompressioparametrit nopeammin kättelevältä osayhteydeltä, 5 muunnetaan mainittu datakompressioneuvottelupyyntö hitaammin kättelevälle osayhteydelle sopivaksi, lähetetään muunnettu datakompressioneuvottelupyyntö hitaammin kättelevälle osayhteydelle, vastaanotetaan datakompressioneuvotteluvaste hitaammin kättele10 vältä osayhteydeltä, muunnetaan mainittu datakompressioneuvotteluvaste nopeammin kättelevälle osayhteydelle sopivaksi, lähetetään sovitettu datakompressioneuvotteluvaste nopeammin kättelevälle osayhteydelle. 15 4. Patenttivaatimuksen 3 mukainen menetelmä, tunnettu siitä, että vasteena datakompressioneuvottelupyynnön ja toisien kompressionparametrien vastaanottamiselle hitaammin kättelevältä osayhteydeltä ennen mainitun muunnetun datakompressioneuvottelupyynnön lähettämistä, johdetaan ensimmäisistä ja toisista kompressioparametreista molemmille osapuolille so20 pivat kompressioparametrit ja lähetetään mainitut johdetut kompressioparametrit kättelyvastauksena ensimmäiselle ja toiselle osayhteydelle. 5. Patenttivaatimuksen 1, 2, 3 tai 4 mukainen menetelmä, tunnettu siitä, että vasteena päästä-päähän datakompressioneuvottelun epäonnistumiselle yritetään suorittaa datakompressioneuvottelu yhdellä osayhtey25 della. · · :6. Jonkin edellisen patenttivaatimuksen mukainen menetelmä, tunnettu siitä, että ensimmäinen tietoliikennejärjestelmä on digitaalinen :T: matkaviestinjärjestelmä ja ensimmäinen laite on matkaviestin. 7. Jonkin edellisen patenttivaatimuksen mukainen menetelmä, :·’ 30 tunnettu siitä, että osayhteyksien virheenkorjausprotokollat ovat erilaiset. ].. t 8. Tietoliikenneverkko, joka käsittää Verkkosovittimen toiseen tietoliikenneverkkoon liittymistä varten, «I
- 44 I välineet, joilla pystytetään tietoliikenneverkon sisällä ensimmäisen datasiirtolaitteen ja Verkkosovittimen välille ensimmäinen osayhteys, jossa käytetään virheenkorjausprotokollaa, välineet, joilla pystytetään Verkkosovittimen ja toisen tietoliikenne5 verkon datasiirtolaitteen välille toinen osayhteys, joka käyttää virheenkorjausprotokollaa, datakompressiovälineet ensimmäisessä ja toisessa datasiirtolaitteessa, tunnettu siitä, että Verkkosovitin on järjestetty viivästämään verkkosovittimessa nope10 ämmin kättelevän osayhteyden virheenkorjausprotokollan pystytystä ja/tai datakompressioneuvottelua, kunnes hitaammin kättelevän osayhteyden virheenkorjausprotokollan muodostus on saatettu loppuun ja datakompressioneuvottelu voitu aloittaa. 9. Patenttivaatimuksen 8 mukainen tietoliikenneverkko, t u n - 15 nettu siitä, että Verkkosovitin käsittää välineet ensimmäisen virheenkorjausprotokollan mukaisten datakompressioneuvottelusanomien vaihtamiseksi ensimmäisen datasiirtolaitteen ja Verkkosovittimen välillä ensimmäisellä osayhteydellä, välineet toisen virheenkorjausprotokollan mukaisten datakompres20 sioneuvottelusanomien vaihtamiseksi Verkkosovittimen ja toisen datasiirtolaitteen välillä toisella osayhteydellä, välineet, joilla datakompressioneuvottelusanomien vaihto ensimmäisellä osayhteydellä ja datakompressioneuvottelusanomien vaihto toisella osayhteydellä ajoitetaan toisiinsa nähden siten, että aikaansaadaan näennäi25 nen päästä-päähän datakompressioneuvottelu ensimmäisen ja toisen datalaitteen välillä. 10. Patenttivaatimuksen 8 tai 9 mukainen tietoliikenneverkko, tunnettu siitä, että Verkkosovitin käsittää välineet, joilla johdetaan ensimmäiseltä ja toiselta datasiirtolaitteelta 30 vastaanotetuista ensimmäisistä ja toisista ehdotetuista datakompressioparametreista yhteiset datakompressioparametrit, jotka lähetetään vastauksena sekä ensimmäiselle että toiselle datasiirtolaitteelle. 11. Patenttivaatimuksen 10 mukainen tietoliikenneverkko, tunnettu siitä, että Verkkosovitin käsittää välineet, joilla vastaanotetaan nopealta osayhteydeltä datakompressioneuvottelupyyntö ja ensimmäiset kompressioparametrit, välineet, joilla tallennetaan ensimmäiset kompressioparametrit, välineet, joilla vastaanotetaan datakompressioneuvottelupyyntö ja
- 55 toiset kompressioparametrit hitaammalta osayhteydeltä, välineet, joilla johdetaan ensimmäisistä ja toisista kompressioparametreista molemmille osapuolille sopivat kompressioparametrit, välineet, joilla lähetetään mainitut johdetut kompressioparametrit neuvotteluvastauksena ensimmäiselle ja toiselle osayhteydelle.
- 610 12. Patenttivaatimuksen 8 tai 9 mukainen tietoliikenneverkko, tunnettu siitä, että ensimmäisen ja toisen osayhteyden virheenkorjausprotokollat ovat erilaiset, ja että Verkkosovitin käsittää välineet nopeammalta osayhteydeltä vastaanotetun datakompressioneuvottelupyynnön tai datakompressioneuvotteluvastauksen, joka sisältää 15 kompressioparametrit, muuntamiseksi hitaamman osayhteyden virheenkorjausprotokollan mukaiseksi ja lähettämiseksi hitaammalle osayhteydelle, välineet hitaammalta osayhteydeltä vastaanotetun datakompressioneuvottelupyynnön tai datakompressioneuvotteluvastauksen, joka sisältää kompressioparametrit, muuntamiseksi nopeamman osayhteyden virheenkor20 jausprotokollan mukaiseksi ja lähettämiseksi nopeammalle osayhteydelle.
- 713. Jonkin patenttivaatimuksen 8-12 mukainen tietoliikenneverkko, tunnettu siitä, että Verkkosovitin käsittää välineet kompressoidun datan siirtämiseksi sellaisenaan Verkkosovittimen läpi onnistuneen päästä-päähän datakompressioneuvottelun jälkeen. 25
- 814. Jonkin patenttivaatimuksen 8-13 mukainen tietoliikenneverkko, tunnettu siitä, että Verkkosovitin on sovitettu vasteena päästä-päähän datakompressioneuvottelun epäonnistumiselle suorittamaan datakompressioneuvottelu yhdellä osayhteydellä.
- 915. Patenttivaatimuksen 14 mukainen tietoliikenneverkko, t u n 30 n e 11 u siitä, että Verkkosovitin käsittää välineet datakompression suorittamiseksi datalle, joka siirretään datakompressiota käyttämättömältä osayhteydeltä datakompressiota käyttävälle osayhteydelle, välineet datadekompression suorittamiseksi datalle, joka siirretään datakompressiota käyttävältä osayhteydeltä datakompressiota käyttämättömälle osayhteydelle.
- 1016. Jonkin patenttivaatimuksen 8-15 mukainen tietoliikenneverkko, 5 tunnettu siitä, että Verkkosovitin käsittää välineet, joilla viivästetään nopeamman osayhteyden virheenkorjausprotokollan pystyttämistä jättämällä vastaamatta vastaanotettuihin pystytyssanomiin virheenkorjausprotokollan salliman ajan tai kunnes hitaamman osayhteyden virheenkorjausprotokolla pystytetty. 10
- 1117. Jonkin patenttivaatimuksen 8-16 mukainen tietoliikenneverkko, tunnettu siitä, että ensimmäinen tietoliikenneverkko on digitaalinen matkaviestinverkko, ensimmäinen osayhteys on datayhteys matkaviestinverkossa ja ensimmäinen laite on matkaviestin.
- 1218. Patenttivaatimuksen 17 mukainen tietoliikenneverkko, tun- 15 nettu siitä, että toinen osayhteys on jokin seuraavista:digitaalinen datayhteys ISDN-verkossa, modeemiyhteys PSTN-verkossa, V.120-yhteys ISDN-verkossa, datayhteys matkaviestinverkossa.
- 1319. Verkkosovitin ensimmäisen tietoliikenneverkon ensimmäisen osayhteyden liittämiseksi toisen tietoliikenneverkon toiseen osayhteyteen, kun
- 1420 molemmilla osayhteyksillä käytetään jotain virheenkorjausprotokollaa ja datasiirtolaitteet osayhteyksien päissä käsittävät datakompressiovälineet, tunnettu siitä, että Verkkosovitin on järjestetty viivästämään verkkosovittimessa nopeammin kättelevän osayhteyden virheenkorjausprotokollan pystytystä ja/tai datakompressioneuvottelua, kunnes hitaammin kättelevän osayhteyden vir25 heenkorjausprotokollan muodostus on saatettu loppuun ja datakompressioneuvottelu voitu aloittaa. 20. Patenttivaatimuksen 19 mukainen Verkkosovitin, tunnettu siitä, että Verkkosovitin käsittää välineet ensimmäisen virheenkorjausprotokollan mukaisten data30 kompressioneuvottelusanomien vaihtamiseksi ensimmäisen datasiirtolaitteen ja Verkkosovittimen välillä ensimmäisellä osayhteydellä, välineet toisen virheenkorjausprotokollan mukaisten datakompressioneuvottelusanomien vaihtamiseksi Verkkosovittimen ja toisen datasiirtolaitteen välillä toisella osayhteydellä, välineet, joilla datakompressioneuvottelusanomien vaihto ensimmäisellä osayhteydellä ja datakompressioneuvottelusanomien vaihto toisella osayhteydellä ajoitetaan toisiinsa nähden siten, että aikaansaadaan näennäinen päästä-päähän datakompressioneuvottelu ensimmäisen ja toisen data5 laitteen välillä.
- 1521. Patenttivaatimuksen 19 tai 20 mukainen Verkkosovitin, tunnettu siitä, että Verkkosovitin käsittää välineet kompressoidun datan siirtämiseksi sellaisenaan Verkkosovittimen läpi onnistuneen päästä-päähän datakompressioneuvottelun jälkeen. 10
- 1622. Jonkin patenttivaatimuksen 19-21 mukainen Verkkosovitin, tunnettu siitä, että Verkkosovitin on sovitettu vasteena päästä-päähän datakompressioneuvottelun epäonnistumiselle suorittamaan datakompressioneuvottelu yhdellä osayhteydellä.
- 1723. Patenttivaatimuksen 22 mukainen Verkkosovitin, tunnettu 15 siitä, että Verkkosovitin käsittää välineet datakompression suorittamiseksi datalle, joka siirretään datakompressiota käyttämättömältä osayhteydeltä datakompressiota käyttävälle osayhteydelle, välineet datadekompression suorittamiseksi datalle, joka siirretään 20 datakompressiota käyttävältä osayhteydeltä datakompressiota käyttämättömälle osayhteydelle.
- 1824. Jonkin patenttivaatimuksen 19-23 mukainen Verkkosovitin, tunnettu siitä, että Verkkosovitin käsittää välineet, joilla viivästetään nopeamman osayhteyden virheenkorja25 usprotokollan pystyttämistä jättämällä vastaamatta vastaanotettuihin pystytyssanomiin virheenkorjausprotokollan salliman ajan tai kunnes hitaamman osayhteyden virheenkorjausprotokolla pystytetty.
Independent claims18
86 paragraphs, as filed
Data compression negotiation in a telecommunication system
The invention relates generally to data transmission in telecommunication systems, in particular to the implementation of data compression on a data transmission connection having at least two sections using an error correction protocol.
In modern digital mobile communication systems, traffic channels have the possibility of establishing a circuit-switched data transmission connection, by means of which a data terminal connected to a mobile station's data interface can transmit data to a mobile network (e.g. Typically, the maximum transmission rate of such data transmission is determined by the maximum capacity of the data channel to be established by radio.
Data compression is widely used to increase the efficiency of data transmission. The data compression algorithm removes any redundancy at the transmission end from the user data stream, as a result of which the amount of data to be transmitted is reduced. At the receiving end, the decompression algorithm expands the user data back to its original form. Typical maximum compression ratios given by compression algorithms are 2: 1 ... 4: 1, which allows up to 20 19200/38400 bit / s user data streams to be adapted to the cellular radio system
9600 bit / s to the data channel. However, the actual compression ratios achieved by compression algorithms are highly dependent on the type of user data. There are several standard or defacto standard data compression methods. For example, data modems generally support ITU-T V.42 bis and MNP5 methods. For example, in the digital GSM mobile communication system, the recommendations specify that the ITU-T V.42 bis compression method is used between the mobile station MS and the Network Adapter IWF.
Data compression methods usually require completely error-free data transmission, as even a small transmission error confuses the decompression algorithm at the receiving end. For example, ITU-T V.42 bis is based on the dynamic construction of compression trees according to certain rules at both the transmitting and receiving ends. If uncorrected transmission errors occur, trees develop differently and data becomes corrupt. Therefore, the most efficient error correction must be used throughout the transmission link to prevent transmission errors.
In modems, the error correction layer V.42 bis below the data compression is ITU-T V.42 (Link Access Protocol for Modems). In digital transmission via PSTN (Public Switched Telephone Network) or ISDN (Integrated Services Digital Network), the error correction layer below V.42 bis data5 compression may be e.g. the V.120 protocol, which operates in multifram mode (i.e. retransmission). The aforementioned error correction protocols are designed for error conditions that are typical of leased lines but are inadequate or unsuitable for special conditions such as a radio link. Therefore, it has been necessary to implement our own error correction solutions within the mobile communication system.
For example, in the GSM system, the error correction layer V.42 bis below the data compression is the radio link protocol RLP, which is also based on frame retransmission.
The use of data compression must somehow be agreed upon and any compression parameters must be negotiated before data transfer can begin. In the GSM system, both parties, i.e. the mobile station MS and the mobile station MSC, indicate their data compression support in the connection establishment signaling. In addition, after the RLP protocol is set up, inband negotiation takes place on the RLP protocol XID frames between the MS and the IWF. On a modem connection, 20 inband negotiations take place with VID2 protocol XID frames after the V.42 error correction protocol is set up between the modems. On a V.120 connection, inband negotiation takes place on the XID frames of the V.120 protocol after the V.120 error correction protocol is set up.
In practice, there are data connections that consist physically25 and separately in terms of protocol, for example GSM data call via PSTN (the connection consists of two parts: 1) GSM traffic channel with protocol and 2) modem connection via PSTN) or GSM data call via ISDN ( two sections: 1) GSM traffic channel with protocol and 2) ISDN protocol, e.g. V.120). In such a case, there are two possibilities to provide data compression for the entire connection: 1) Separate compression for each section (e.g., as currently defined in the GSM Recommendations) and 2) end-to-end compression (as implemented by some mobile manufacturers in the GSM system).
There are problems with both implementation options. In case 1), a network adapter IWF located between different sections requires high processing power to perform data compression in both directions for two different sections. Furthermore, the IWF requires a large memory to support the compression trees of two different compression units. A high-speed interface is required between the compression units in order to transfer uncompressed data from one compression unit to another.
The implementation of end-to-end compression (case 2) may be such that the calling party requests a transparent synchronous connection to be able to shake off the error correction and end-to-end data compression protocol (e.g. in a GSM / PSTN data call between MS and PSTN modem transparently through IWF). ). There are several drawbacks to this method:
i) The error correction protocol may not be optimized for both sections. For example, the debugging protocols V.42 and
MNP4 are not optimal for the GSM traffic channel. The frame length is much longer than the RLP frame length of the radio link protocol. In poor radio conditions, the retransmission probability of these long frames is much higher than that of RLP frames, effectively blocking the traffic channel.
ii) If the end-to-end error correction and / or data compression negotiation fails, it is no longer possible to obtain data compression for the sub-connections. For example, suppose a GSM / ISDN call has a baud rate of 2 * 14.4. kbits / s = 28.8 kbit / s on the GSM traffic channel (between the MS and the IWF) and 56 kbit / s on the ISDN traffic channel (between the IWF and the ISDN terminal). If end-to-end data compression can be negotiated, the uncompressed data rate could typically be 3 * 28.8 kbits / s = n. 90 kbit / s. If end-to-end compression negotiation fails and compression is not possible even for a partial connection, the data rate is only 28.8 kbits / s. If GSM compression could be negotiated between the IWF and the MS when the end-to-end compression negotiation fails, the end-to-end data rate will be lower than the data rates of the two access portions, i.e., 56 kbits / s.
(iii) support for bearer services is needed in both the mobile station and the mobile network. For example, in GSM, the availability of synchronous network services is not as good as the availability of asynchronous network104674 services. Virtually every GSM network and every mobile station capable of data transmission supports asynchronous network services.
WO9405104 discloses a digital mobile communication system in which end-to-end compression is used between the mobile station MS and the PSTN modem, but a different error correction protocol is used on the traffic channel and the modem connection of the mobile communication network. The digital transmission link between the mobile station and the IWF modem over the radio path is a non-transparent asynchronous transmission link, in which the radio system's own error correction protocol (e.g. RLP), which is optimized to correct radio communication errors. The error correction required for a modem connection is accomplished by placing in the IWF modem an error correction protocol similar to that of a PSTN modem at the other end of the modem connection. Thus, in the mobile communication system, the data compression functions are located in the mobile station and the error correction of the modem connection in the IWF modem, which in no way participates in the data compression. However, at the beginning of the modem connection, the IWF modem, by handshake with the PSTN modem, negotiates the compression parameters used in the data transmission and transmits them to the mobile station MS.
WO9405104 solves some of the problems described above, but has other drawbacks. First, the method disclosed in WO9405104 requires 20 non-standard operations. For example, in GSM, the mobile station MS must stop setting up the radio link protocol RLP in order to wait for compression parameters from the IWF. In addition, some special assignment mechanism is needed to access the special functionality required by the method in the IWF. Second, the mobile station cannot participate in the negotiation of compression parameters, which is why it is not always possible to achieve optimal conditions (the best common set of parameter values). Third, there is no fallback option in this known method, i.e., if end-to-end data compression cannot be set up, it is no longer possible to set up data compression for a partial connection (e.g., between a mobile station MS and an IWF).
Similar problems occur at interfaces between other telecommunication networks.
It is an object of the invention to eliminate or alleviate the above problems.
These and other objects of the invention are achieved by a method and a system which are characterized by what is stated in the independent claims. Preferred embodiments of the invention are the subject of dependent claims.
In the present invention, the end-to-end connection has at least two separate sub-connections with error correction protocols. Subconnections may have different physical layer connections or their debugging protocols may be different. The network adapter IWF according to the invention is integrated between these sub-connections so that the sub-connections can communicate with each other during the erection phase of the traffic channel in order to send data compression parameters to each other. The IWF intervenes in end-to-end data compression negotiation, performs protocol conversions for messages to be transferred from one connection to another, synchronizes the partial connections if necessary by delaying the establishment of a faster partial connection and compression negotiation, modifies the compression parameters provided by the parties.
A typical problem with sub-connections using a different physical layer connection or different protocols is that the erection of the error correction link protocol and / or data compression negotiation (handshake) is faster on one sub-connection than on the other. In this description and in the claims, fast and slow sub-connection means a faster connection (handshake) that can set up the error correction protocol and a sub-connection that can set up (shake) the error correction protocol more slowly, respectively. In this case, in the call set-up mode25, various controls, such as time control or retransmission control, are triggered before the error correction protocol is even set up with a slower partial connection. Due to different delays or timing differences, the same can also happen with partial connections that are approximately the same speed (e.g., a call between two mobile stations in the same mobile network). According to the Kek30 invention, the IWF slows down the establishment of a faster sub-connection error correction link protocol and / or data compression negotiation, while keeping the procedure on the sub-connection alive. This is done, for example, by delaying responses to messages from a faster partial connection for as long as necessary or possible. However, if an error correction protocol has to be set up during this delay maneuver, and a slower partial connection error correction protocol has not yet been set up and data compression negotiation has not started, a faster part connection can be put into a disconnected mode where no data transfer can start but data5 compression can start. In this case, the response to the data compression negotiation messages is delayed until the slower partial connection has reached the same stage in the compression negotiation. In general, it is very important to try to slow down the faster sub-connection already in the error correction protocol setup phase, because delaying data compression negotiation alone due to the maximum number of retransmissions and time controls typically does not give the slower sub-connection enough time to access the same data compression negotiation.
The following describes a procedure according to a preferred embodiment of the invention when a sub-connection with a faster setup initiates data15 compression negotiation. At the beginning of the connection, the IWF tries, as far as possible, to perform the high-speed partial connection delay according to the invention. The fast connection is called link A and the slower partial connection is called link B. The IWF stores the parameters of the data compression negotiation, which is initiated by the terminal A at the farthest end of the link A. If the second sub-connection, link B, is not yet up and running, the IWF continues to delay link A by failing to respond to the data compression negotiation offer received from terminal A. This typically causes terminal A to repeat the negotiation offer after triggering a certain time control.
If link B is set up while the IWF is still delaying the setting up of 25 links A, the IWF sets up link A (both links in disconnected mode) and starts a timer to wait for possible data compression negotiation requests. If the request is received from both sub-connections, the IWF responds to both terminal A and terminal B with common parameter values derived from both negotiation offers. If no data30 compression requests are received, the IWF may attempt to negotiate data compression on one of the sub-branches (depending on the rules of the protocols used).
Once link B is set up (and directed to disconnected mode by the IWF), and a data compression negotiation offer has already been received from terminal A, the compression parameters of terminal A are sent over link B to terminal B. The negotiation offer of terminal A is still unanswered. In negotiation on link B, normal timer monitoring and retransmission mechanism are applied. At the same time, the IWF ignores all retransmissions of the negotiation offer from terminal A. After receiving the acknowledgment from the terminal B, the IWF matches the response to the link A, i.e. responds to the negotiation request of the terminal A with the data compression parameters received from the terminal B. Thus, the end-to-end negotiation of the data compression parameters is completed.
If the IWF receives a data compression negotiation request from the terminal 10 from the device B before it has itself sent the negotiation request, the IWF responds to both the terminal A and the terminal B with common parameter values derived from both negotiation offers.
If data compression cannot be set on link B (due to, for example, a negative response from terminal B or an IWF decision resulting from, for example, a timer trip), the IWF can still set up compression on link A, i.e. between terminal A and IWF, by responding to terminal A's negotiation request. .
When the data compression negotiation is completed, the IWF initiates the transition from the disconnected mode to the data transmission mode on both sub-connections, link A and link B.
In another embodiment of the invention, a procedure is described when a sub-connection with a slower set-up initiates compression negotiation. Initially, the IWF will endeavor to delay, as far as possible, the erection and compression negotiation of a faster partial connection, link A. After setting up link B and controlling the dis25 connected modes, the IWF starts a timer and starts waiting for a possible data compression negotiation request. After receiving the data compression negotiation request from the terminal B, the IWF responds to the error correction protocol link setup message of the terminal A and matches the data compression request received from the terminal B to the link A to be sent to the terminal 30 A. If no request is received before the timer starts,
Data compression negotiation on link A is subject to normal time control and retransmission mechanism. At the same time, the IWF ignores all retransmissions of the negotiation offer from terminal B.
After receiving the negotiation response from the terminal A, the IWF matches the response to the link B, i.e. responds to the negotiation request of the terminal B with the data compression parameters received from the terminal A. Thus, end-to-end negotiation of the data compression parameters is performed.
If the IWF receives a data compression negotiation request from terminal A before it has itself sent the negotiation request, the IWF responds to both terminal A and terminal B with common parameter values derived from both negotiation offers.
If data compression cannot be established on link A (due to, for example, a negative response from terminal A or an IWF decision resulting from, for example, a timer trip), the IWF can still establish data compression on link B (i.e., between terminal B and IWF) in response to terminal B's negotiation request.
When the data compression negotiation is completed, the IWF initiates the transition from the disconnected mode to the data transmission mode on both sub-connections, link A and link B.
The invention will now be described in more detail in connection with preferred embodiments, with reference to the accompanying drawings, in which:
Figure 1 shows a GSM mobile communication system,
Figure 2 shows the protocols and functions required for the GSM system in non-transparent asynchronous network services,
Figure 3 illustrates an adapter apparatus according to the invention located in connection with a mobile switching center,
Figure 4 shows a block diagram of a channel controller according to the invention which supports UDI data connections,
Fig. 5 is a flowchart illustrating the operation of an IWF according to the invention in the case of a UDI call originating from a mobile station,
Fig. 6 is a flowchart illustrating the operation of an IWF according to the invention in the case of a UDI data call terminating at a mobile station,
Figure 7 shows a block diagram of a channel controller according to the invention which supports modem calling via a PSTN,
Figures 8, 9 and 10 are flow charts illustrating the operation of the IWF according to the invention in the case of a modem call originating from and terminating at a mobile station.
The invention can be applied to any data connection consisting of separate traffic channel sections. The present invention is particularly suitable for digital mobile communication systems having a data transmission service for data transmission between a mobile station and a fixed network, such as ISDN and PSTN, or another mobile communication network. Mobile communication systems use various multiple access modulation techniques to facilitate traffic involving a large number of mobile users. These techniques include time division multiple access (TDMA), code division multiple access (CDMA), and frequency division multiple access (FDMA). The physical concept of a traffic channel varies in different multiple access methods, being primarily defined by time slot in TDMA systems, spreading code in CDMA systems, radio channel in FDMA systems, a combination thereof, etc. However, the basic idea of the present invention is independent of the traffic channel type and multiple access method used. The present invention is also applicable to wireless local area networks (WLL) or satellite-based mobile networks.
The present invention is particularly suitable for data transmission applications in the pan-European digital mobile communication system GSM (Global System for Mobile Communications) and other GSM-based systems such as DCS1800 (Digital Communication System), as well as the US digital cellular system PCS (Personal Communication System) and the above systems. based WLL systems or satellite systems. The invention will be described below using the GSM mobile communication system as an example. The structure and operation of the GSM system are well known to a person skilled in the art and defined in the GSM25 specifications of the European Telecommunications Standards Institute (ETSI). Reference is also made to the book GSM-System for Mobile Communication, M. Mouly and M. Pautet, Palaiseau, France, 1992; ISBN: 2-95071900-7.
The basic structure of the GSM system is shown in Figure 1. The GSM structure consists of two parts: the base station system BSS and the network sub-system (NSS). The BSS and the mobile stations MS communicate via radio links. In the base station system BSS, each cell is served by the base station BTS. A number of base stations are connected to a base station controller BSC, the function of which is to control the radio frequencies and channels used by the BTS. The BSCt is connected to the mobile switching center MSC. Certain MSCs are connected to other telecommunication networks, such as the public switched telephone network PSTN, and include gateway functions for outgoing and incoming calls to these networks. These MSCs are known as gateway MSCs (GMSCs). In addition, there are at least two databases, the home location register HLR and the visitor location register VLR.
The mobile communication system has adapter functions for adapting the internal data connection of the mobile communication network to the protocols used by the terminals and other telecommunication networks. Typically, the adapter functions are a terminal adapter TAF (Terminal Adaptation Function) at the interface between the mobile station and the data terminal connected to it, and a network adapter IWF (Interworking Function) 10 at the interface between the mobile network and another telecommunication network, usually in connection with a mobile switching center. Typically, a mobile switching center has several types of adapter hardware pools to support various data services and protocols, for example, a modem pool with modems and facsimile adapters for modem and facsimile services, a UDI / RDI rate adapter pool, and so on.
Referring to Figure 1, in the GSM system, a data connection is established between the network terminal TAF 31 of the mobile station MS and the Network Adapter IWF 41 in the mobile network. This connection is a V.110 rate-matched, V.24-compliant, UDI-encoded digital fullduplex connection for data transmission in the GSM network. In the case of non-transparent data services with a GSM connection, the radio link protocol RLP is also used. The TAF adapts the data terminal DTE connected to the mobile station MS to said GSM data connection, which is established over a physical connection using one or more traffic channels. The IWF connects the GSM data connection to a V.110 or V.120 network, such as ISDN or another GSM network, or to another transit network, such as the public switched telephone network PSTN. The CClTT recommendation for a V.120 rate-matched connection is presented in CCITT White Book: V.120.
As previously explained, modern mobile communication systems support a variety of telecommunications and network services. The network services of the GSM system are defined in the specification GSM 02.02 version 5.3.0 and the telecommunications services in the specification30 sa GSM 02.03 version 5.3.0.
Figure 2 shows examples of protocols and functions required in the IWF for non-transparent network services. The non-transparent circuit-switched connection between the terminal adapter TAF and the network adapter IWF on the GSM traffic channel comprises several protocol layers common to all these services. These include various rate adaptation functions RA (Rate Adaptation), such as RA1 'between the terminal adapter TAF and the CCU (Channel Codec Unit) located in the base station system BSS, RA1 between the CCU and the Network Adapter IWF, between the RAA CCU and the transcode TRUA separated from the base station5 RA2 between the transcoder unit TRAU and the Network Adapter IWF. Acceleration matching functions RA are defined in GSM Recommendations 04.21 and 08.20. The communication between the CCU and the TRAU transcoder is defined in GSM Recommendation 08.60. In the radio interface, the RAT rate matched information is further channel coded as defined by GSM Recommendation 5.03, as illustrated by the blocks FEC in the mobile station MS and the CCU. In addition, the IWF and TAF have higher-level protocols that are service-specific. In an asynchronous non-transparent network service, the IWF needs L2R (Layer 2 Relay) and RLP (Radio Link Protocol) protocols as well as a modem or speed adapter in the direction of the fixed network. L2R functionality for 15 non-transparent character-oriented protocols is defined e.g. In the GSM recommendation 07.02. The RLP protocol is defined in GSM Recommendation 04.22. RLP is a frame-structured, balanced (HDLC-type) data transmission protocol in which error correction is based on the request of the receiving retransmission of distorted frames party. The interface between the IWF and, for example, the audio modem 20 MODEM is CCITT V.24 and is denoted by the symbol L2.
The GSM system (Phase 2+) is defined with data compression according to ITU-T V.42 bis, which extends from the mobile station MS to the network adapter IWF. The error correction function is provided by the radio link protocol RLP and not by the 25 ITU-T V.42 protocol. In the protocol structure of Figure 2, the data compression V.42 bis is located in the L2R functionality, which can then also be called L2R bis. The compression function and related parameters are negotiated between the MS and the IWF in the RLP link setup phase using RLP XID frames (XID = Exchange Identification Procedure). The IWF also handles the compression function and parameter negotiation in the link setup phase with the PSTN modem or ISDN terminal.
Figure 3 shows an adapter apparatus or coil 41 located in connection with a mobile switching center MSC. Pool 41 comprises one or more channel controllers 400. Each channel controller 400 may include a single adapter 104674 function or integrated all adapter functions that the channel controller should support. For example, the channel controller may support fixed network UDI / RDI protocols (ITU-TV.110 and / or ITU-T V.120), 3.1 kHz modem functions, fax group 3 functions, and PCM codec functions (PCM encoding / decoding). . Channel 5 controller 400 may be traffic channel specific, as in Figure 3, or alternatively common to a set of traffic channels, e.g., 2 Mbit / s PCM link for all traffic channels. Each channel controller 400 of the IWF pool 41 is connected in parallel with the group switch GSW21 of the MSC. Digital transmission links 22 to the base station systems BSS are also connected to the group switch 21 via central terminals. Further transmission channels 23 are connected to the group switch 21 via central communication terminals ET, such as ISDN or PSTN transmission channels 23. Group switch GSW21 as well as data control equipment and network IWF. The operation of the network adapter IWF is controlled by the IWF controller 44, which, under call control 43, selects and connects a free channel controller 400 for the data connection to the data connection. The IWF controller may further comprise a pool controller, one for each IWF pool. An example of a mobile switching center in which the network adapter hardware shown can be used is Nokia Telecommunications Oy's mobile switching center DX200 MSC.
The channel controller according to a preferred embodiment of the invention implements a flexible handshake of compression parameters in the case of two different sub-connections, i.e. a GSM traffic channel and a fixed network traffic channel. In addition, it allows a non-transparent asynchronous data connection to be set up without data compression, end-to-end data compression or datakom25 compression on at least one sub-connection (e.g. a GSM traffic channel).
Figure 4 is a schematic block diagram illustrating, by way of example, a channel controller 400 for digital (UDI / RDI) data calls embodying the invention. The functions required by the fixed network protocols (e.g., V.120) used in the direction of the fixed network traffic channel 402 are located in the unit 401. The RA1 and RA2 rate matching functions and the L2R / RLP functions in the direction of the GSM traffic channel are performed in the units 405 and 404. The units 401 and 404 can be connected to each other by switching functions S1 and S2 either directly or via the data compression unit 406. When S1 and S2 are in position II, the units 404 and 401 are connected to each other via a data compression unit 406.
In the preferred embodiment of the invention, the data compression unit 406 performs V.42 bis data compression on data transmitted from the fixed network traffic channel 402 to the GSM traffic channel 403 and V.42 bis data decompression in the opposite direction. The data compression unit 406 is typically connected when end-to-end compression negotiation has failed, but data compression is possible on the GSM traffic channel. In this case, higher data rates can also be reached with an end-to-end connection, because the GSM traffic channel is usually slower than, for example, a digital ISDN connection. Switch functions S1 and S2 and units 401 and 404 are controlled by control function 407. Control function 407 10 coordinates link setup handshake and data compression negotiation according to the fixed network protocol (such as V.120) performed by unit 401 in the direction of the fixed network. Accordingly, control function 407 coordinates RLP link setup and data compression negotiation performed by unit 404 with the MS on GSM traffic channel 403. In addition, control function 407 synchronizes data compression negotiation between units 401 and 404 by delaying faster handover link handoff and handshake. If necessary, the control function 407 also changes the compression parameters. The control function 407 is controlled by the IWF controller 44 (Fig. 3).
It should be noted that in a practical application, the channel controller 400 may be implemented with a single signal processor, such as the Texas Instruments C541DSP. Thus, the detailed implementation of the channel controller 400 or IWF pool 41 according to the invention may vary almost indefinitely from one application to another.
The operation of the IWF of Figure 4 and the associated mobile outgoing (MO) and mobile terminating (MT) data call 25 will now be described.
In an outgoing (MO) call from the mobile station MS, the MS sends a call setup message SETUP to the mobile switching center MSC, which contains a BCIE (Bearer Capability Information Element) element indicating the type of call requested and the network services and protocol required for the call. In octet 4 of the BCIE30 element, bit 7 determines, in the direction of the MS network, whether data compression is allowed (b7 = 1) or not (b7 = 0). In the opposite direction, bit 7 of the octet 4 of the network MS, BCIE element indicates whether data compression is possible (b7 = 1) or not (b7 = 0). In the example case, the BCIE element indicates a UDI call in which data compression is allowed (b7). If the BCIE element indicates that data compression104674 is not allowed, the MSC will not initiate any data compression operations. The MSC checks if the network supports data compression. If supported, the MSC sends a CALL PROCEEDING message indicating that data compression is possible. If not, the MSC sends an indication that data compression is not possible.
In a mobile terminating (MT) call, the MSC receives a BCIE element from the visitor location register or the fixed network indicating a UDI call. The MSC sends a SETUP message to the MS in which the BCIE indicates that data compression is allowed (if the network supports data compression). The MS responds with CALL CONFIRM Salo, where the BCIE indicates whether data compression is allowed (b7 = 1) or not (b7 = 0).
The call set-up signaling described above is fully in line with the GSM recommendations. The MSC then allocates the necessary IWF resources by sending an IWF Setup message to the IWF, which also includes the GSM BCIE.
The IWF controller 44 receives a SETUP message 15 from the call control 43 of the MSC containing the BCIE. The IVVF controller 44 analyzes the BCIE. Based on the analysis, the IWF controller reserves or configures a channel controller 400 for the data call. In the exemplary case, a channel controller 400 that supports UDI calling and data compression, such as the channel controller of Figure 4, is configured or reserved for the data call. The channel controller 400 is connected to the line. At this point, the operation of the IWF according to the invention begins, which will be explained with reference to Figures 5-6 for an MO call and with Figures 7-8 for an MT call.
Referring to Figure 5, the control function 407 of the channel controller 400 receives information from the IWF controller 44 that data compression is being used in the call. The control function 407 controls the L2R / RLP unit 404 to start the RLP25 protocol setup. In this case, the unit 404 either sends a SABME message to the mobile station MS and, after receiving the response, sets the RLP link to the Disconnected state. Alternatively, unit 404 may wait for a SABME message from the mobile station MS and set the RLP link to Disconnected with the DM message (step 501). SABME and DM are messages defined for the RLP, V. 120, and V.42 protocols. Dis30 connect mode is an RLP, V.120, and V.42 link mode where data cannot be transferred.
Transmission mode is an RLP, V.120, and V.42 link mode in which data can be transmitted.
The ISDN terminal 1 (Fig. 1) may send a link setup message on the traffic channel 401 to set up the SABME V.120 protocol, if it takes long enough to set up the RLP104674 protocol on the GSM traffic channel 403 so that the monitoring timer starts in the ISDN terminal 1. Control function 407 unit 401 not to respond to V.120 SABME messages sent by the ISDN terminal (step 502). This continues until the RLP link is set up (step 503).
Once the RLP link is set up, the MS sends an XL frame of the RLP protocol to negotiate the use of data compression. When the unit 404 has received the compression negotiation request from the MS (505), the control function 407 stores the data compression parameters received in the XID frame from the MSJ 10 (step 506). In step 507, the control function 407 checks whether a V.120 link setup message (SABME) has already been received from the ISDN terminal. If a V.120 SABME message has already been received, the unit 401 responds by sending a DM message to the ISDN terminal setting the V.120 link to disconnect mode (step 508). If the unit 401 has not yet received the V.120 SABME message from the ISDN terminal 15, the unit 401 sends a V.120 link setup request (SABME) to the ISD terminal (step 509). The ISDN terminals are then expected to respond according to the V.120 protocol (step 510).
Steps 508 and 510 proceed to step 511, where the control function 407 IWF transmits the data compression parameters received from the MSJ to the ISDN20 terminal V.120 in the XID frame. In step 512, it is checked whether a positive response has been received from the ISDN terminal. A positive response is a V.120 XID frame with a compression parameter accepted by the ISDN terminal. They may be the same as those sent to the ISDN terminal in 511 or they may be modified by the ISDN terminal. When a positive response is obtained in step 512, the control function 407 transmits to the mobile station MS, via the unit 404, the data compression parameters received from the ISDN terminal V.120 in the XID frame (step 513). Data compression is now negotiated end to end, and the control function 407 controls switches S1 and S2 to position I, where the data compression unit 406 is bypassed (step 514). The RLP and V.120 links are then set to transmission mode (step 515). Unit 404 drives the RLP protocol with the mobile station MS and unit 401 drives the V.120 protocol with the ISDN terminal. The compressed data is transmitted as is between the RLP and V.120 protocols (between units 404 and 401).
If no positive response is received in step 511, it is checked at 516 whether the response is negative. In the negative response, the ISDN terminal indicates that data compression cannot be used. If no negative response is also received, it is checked in step 519 that the compression parameters can be retransmitted. Typically, retransmission is allowed at certain intervals and a predetermined number of times N. If there are still retransmissions, the process returns to step 511. If a negative response is received or retransmissions can no longer be made, the process proceeds to step 517, where data compression is set up only for the GSM10 traffic channel. In this case, the control function 407 sends to the mobile station MS an RLPXID frame containing the data compression parameters selected by the control function 407. Thereafter, the control function 407 controls the switches S1 and S2 to the position II, where the data compression unit 406 is connected to the line. In this case, all the uncompressed data coming from the unit 401 is compressed in the unit 406 επί 5 nen transmission to the GSM traffic channel. Accordingly, all compressed data coming from unit 404 is decompressed at unit 406 before being transmitted to the fixed network traffic channel 402.
Referring to Figure 6, in an MT call terminating at a mobile station, the control function 407 of the channel controller 400 receives information from the IWF controller 44 that data compression is being used in the telephone. The control function 407 controls the L2R / RLP unit 404 to start setting up the RLP protocol. The call set-up then proceeds through steps 701, 702, 703, 705, 706 of Figure 7, which are identical to steps 501, 502, 503, 505 and 506 of Figure 5.
The call set-up then proceeds to step 707, where the control function 407 responds to the V.120 link setup request (SABME) sent by the ISDN terminal with a DM message setting the V.120 link to disconnected mode. In step 708, the ISDN terminal V.120 is expected to have an XID frame requesting data compression negotiation and providing compression parameters. When the XID frame is received, the control function 407 compares the data compression parameters received from the MS 30 with the data compression parameters received from the ISDN terminal and determines common values of the data compression parameters that are acceptable to both the MS and the ISDN terminals. The control function 407 then sends the common data compression parameter values to the MSJIe RLP in the XID frame in response to the XID negotiation offer sent by the MS, and
To the ISDN terminal V.120 in the XID frame in response to the XID negotiation offer sent by the ISDN terminal (step 709). Thus, this compression is negotiated end to end. The control function 407 controls the switches S1 and S2 to the position I, where the data compression unit 406 is bypassed and the compressed data is transferred as such between the units 404 and 401.
If the negotiation request is not received from the ISDN terminal in step 708, a negative response is received or retransmissions can no longer be made, step 712 is entered, where data compression is set up only for the GSM traffic channel. In this case, the control function 407 sends to the mobile station 10 an RLP-XID frame containing the data compression parameter selected by the control function 407. Thereafter, the control function 407 controls the switches S1 and S2 to the position II, where the data compression unit 406 is connected to the line (step 713). In this case, all uncompressed data coming from the unit 401 is compressed in the unit 406 before being sent to the GSM traffic channel. Accordingly, all compressed data from unit 404 is decompressed at unit 406 before being transmitted to the fixed network traffic channel 402.
Fig. 7 is a schematic block diagram illustrating, by way of example, a channel controller 400 for modem calls according to a second embodiment of the invention. The rate matching unit 405, the L2R / RLP unit 404 and the data compression unit 406 and switches S1 and S2 required in the direction of the GSM traffic channel are similar in structure and operation as in the channel controller of Fig. 4. The difference from the channel controller of Fig. 4 is that the fixed network protocol unit 401 of Fig. 4 has been replaced by a modem function unit 408.
The modem function unit 408 comprises a modulation and demodulation unit 409, an error correction unit 410 and a data compression unit 411. The error correction unit 410 implements error correction according to the V.42 protocol. The error correction unit 410 can be connected to each other by the switch functions S1, S2, S3 and S4 either directly or via the data compression unit 411 or the data compression unit 406. When switches S1-S4 are in position I, units 410 and 404 are connected directly to each other, whereby the compressed data passes through the IWF as such. If end-to-end compression negotiation has failed, but data compression is used on the GSM traffic channel, switches S3 and S4 are in position I, which bypasses the compression unit 411, and switches S1 and S2 are in position II, which connects the compression unit 406 to the line. In this case, the data compression unit 406 performs V.42 BIS data compression on the data transmitted from the fixed network traffic channel 402 to the GSM traffic channel 403 and V.42 data decompression in the opposite direction. If end-to-end data compression negotiation has failed, but data compression is used over a modem connection, switches 5 S1 and S2 are in position I, which bypasses data compression unit 406 and switches
S3 and S4 are in position II, which connects the data compression unit 411 to the line. In this case, the unit 411 performs V.42 bis data compression on the data transmitted from the GSM traffic channel 403 to the fixed network traffic channel 402 and V.42 bis data decompression in the opposite direction. The switch functions S1-S4 and the individual ropes 404 and 408 are controlled by the control function 407 on the same principles as in Fig. 8.
The operation of the channel controller of Figure 7 and the associated mobile outgoing (MO) and mobile terminating (MT) data call set-up will now be described. In a modem call, the MSC and MS indicate in the call set-up signaling that they both support data compression, as previously described in connection with Figure 4. The MSC then allocates the necessary IWF resources by sending an IWF setup message to the IWF, which also includes the GSM-BSCIE.
The IWF controller 44 receives a SET UP message from the call control 43 of the MSC containing the BCIE. The IWF controller 44 analyzes the BCIE. Based on the analysis pe20, the IWF controller allocates or configures a channel controller for the data call that supports modem calling and data compression, such as the channel controller of Figure 9. The channel controller 400 is connected to the line. At this stage, the operation of the IWF according to the invention begins, which will be explained with reference to Figures 8 and 9 for the MO call and with reference to Figures 8 and 10 for the MT call.
Referring to Figure 8, the control function 407 of the channel controller 400 receives information from the IWF controller 44 that data compression is being used in the call. The control function 407 controls the modem function unit 408 to initiate a modem handshake with the PSTN modem (step 101). At the same time, a counter that counts the number of SABME messages sent by the MS is set to 0. In step 102, it is checked whether the modem handshake is completed. If not, it is checked whether the MS sent the first SABME message or the retransmit message after the retransmission timer expired (step 103). If transmitted, the control function 407 fails to respond to the message and increments the counter by one (step 104), after which it is checked whether the counter has reached the value N (step 105). N is the maximum number of retransmissions of the MS or less than the maximum number of retransmissions. Since, according to the invention, it is desired to delay the establishment of the RLP link as long as possible, if the modem handshake has not yet ended, the IWF does not respond until N is sent. If, in step 105, the count value is less than N, the process returns to step 102 to check whether the modem handshake is complete.
If the modem handshake is found to be terminated in step 102, the control function 407 finally sends a DM message to the MS setting the RLP link to the disconnected mode (step 106). The MS sends an XID frame to the IWF to negotiate the use of data compression (step 107). The control function 407 stores the data compression parameters received in this XID frame (step 108). However, the control function 407 does not respond to the XID frame because the compression negotiation on the modem connection has not yet been performed. Because the negotiation over the modem connection is slow, the MS may retransmit the XID frame several times without a response.
If, in step 105, the modem handshake has not yet ended, even though the MS has retransmitted the SABME message N times, the control function 407 responds to the SABME message sent by the MS with a DM message to establish the RLP link in disconnected mode (step 109). It is then checked again whether the modem handshake is completed (step 110). If so, go to step 107. If not, check in step 111 whether the MS has sent an XID frame. If not, return to step 110. If so, the XID frame is left unanswered and the compression parameters received from the MS in the RLP XID frame are stored (step 112). It then waits until the modem handshake is complete (step 100).
Steps 108 and 100 of Figure 8 proceed to step 101 of Figure 9, where the control function 407 sends to the PSTN modem V.42 an XID frame containing the compression parameters received from the MS. Normally, the PSTN modem responds by transmitting a V.42 XID frame that contains either the compression parameters transmitted in step 30113 or the compression parameters modified by the PSTN modem. If it is determined at step 114 that the PSTN modem has sent such a positive response, the control function 407 sends the data compression parameters received from the PSTN modem to the mobile station RLP in the XID frame in response to the mobile station MS's initial (possibly retransmitted) XID negotiation offer (step 115). Data compression is now negotiated end-to-end. The control function 407 controls all switches S1-S4 to position I, where both data compression units 406 and 411 are bypassed (step 116). In this case, the compressed data flows as such between units 5,404 and 410. The RLP and V.42 links are then set to transmission mode and data transfer can begin (step 117).
If no positive response is received from the PSTN modem in step 114, a negative response is checked (step 118). If not, it is checked whether retransmission can be performed (step 119). If retransmission is performed, the process proceeds to step 113. If a negative response is received or retransmission is not performed, end-to-end data compression negotiation has failed. In this case, the control function 407 can set up data compression for the GSM traffic channel (step 120). In this case, it sends the compression parameter of its choice to the mobile station in the RLP XID frame. Thereafter, the control operation 407 connects (step 121) the data compression unit 406 to the line (switches S1 and S2 in position II) and bypasses the data compression unit 411 (switches S3 and S4 in position I).
The modem call terminating at the mobile station proceeds to a successful modem handshake in the same manner as the MO call in Figure 8. After a successful modem handshake, the process proceeds to Figure 10, where the PSTN modem is expected to send a V.42 XID frame containing data compression parameters (step 122). When the XID frame is received, the control function 407 compares the data compression parameters received from the mobile station MS with the data compression parameters received from the PSTN modem and determines common parameter values that are acceptable to both the mobile station MS and the PSTN modem. The control function 407 then sends these common data compression parameter values to the mobile station MS RLP in the XID frame in response to the mobile station MS's original (possibly retransmitted) XID negotiation offer and PSTN modem V.42 in the XID30 frame in response to the PSTN modem XID negotiation.
This is how end-to-end data compression is negotiated. The control function 407 then sets the switches S1-S4 to the position I, where both data compression units 406 and 411 are bypassed (step 124). The RLP and V.42 links are then set to transmission mode (step 130). If the control function 407 does not receive the XID104674 frame from the PSTN modem, it determines common parameter values that are acceptable to both the mobile station MS and the PSTN modem. The control function 407 then sends these common data compression parameter values to the mobile station MS RLP in the XID frame in response to the mobile station MS's initial 5 (possibly retransmitted) XID negotiation offer and PSTN modem V.42 in the XID frame in response to the PSTN modem XIDneuv. This is how end-to-end data compression is negotiated. The control function 407 then sets the switches S1-S4 to the position I, where both data compression units 406 and 411 are bypassed (step 127). The RLP and V.42 links are then set to the transmission mode (step 130).
If the control function 407 does not receive the XID frame from the PSTN modem within a certain time, it considers the end-to-end negotiation failed and sets up data compression only for the GSM traffic channel. In this case, the control function 407 transmits the self-selected compression parameters RLP-XID15 in the frame to the mobile station MS (step 124). The control function 407 then connects the data compression unit 406 to the line (switches S1 and S2 in position II) and bypasses the data compression unit 411 (switches S3 and S4 in position I). Then go to step 123.
It will be apparent to one skilled in the art that as technology advances, the basic idea of the invention can be implemented in many different ways. The invention and its embodiments are thus not limited to the examples described above but may vary within the scope of the claims.
7 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7
20 members in 11 offices
Priority claims2
| Document | Office | Kind | Date |
|---|---|---|---|
| 974307 | Finland | A | |
| FI19970004307 | – | – | – |
Members20
| Document | Office | Kind | |
|---|---|---|---|
| FI974307A | Finland | A | |
| FI974307A7 | Finland | A7 | |
| CA2308408A1 | Canada | A1 | |
| WO9927691A1 | World Intellectual Property Organization (WIPO) | A1 | |
| AU1239299A | Australia | A | |
| ZA9810714B | South Africa | B | |
| FI104674BThis record | Finland | B | |
| EP1042892A1 | European Patent Office (EPO) | A1 | |
| CN1279857A | China | A | |
| CN1148928C | China | C | |
| US6898181B1 | United States of America | B1 | |
| US2005286418A1 | United States of America | A1 | |
| EP1042892B1 | European Patent Office (EPO) | B1 | |
| AT328446T | Austria | T | |
| ATE328446T1 | Austria | T1 | |
| DE69834743D1 | Germany | D1 | |
| DE69834743T2 | Germany | T2 | |
| ES2264217T3 | Spain | T3 | |
| CA2308408C | Canada | C | |
| US8514710B2 | United States of America | B2 |
Numbers
- Publication, DOCDB
- 104674
- Publication, EPODOC
- FI104674B
- Application
- 974307
- Application, DOCDB
- 974307
- Application, EPODOC
- FI19970004307
Titles3
- Finnish
- Datakompression neuvottelu tietoliikennejärjestelmässä
- Swedish
- Förhandling av datakompression i ett telekommunikationsnät
- English
- Data compression negotiation in a communication system
Classification
- CPC, 4
- H04L9/40
- H04W92/02
- H04L69/24
- H04L69/323
- IPC, 4
- H04L1 00
- H04L29 06
- H04L29 08
- H04W92 02
