Patent Application
20100296468
This application claims the benefit of the Spanish Patent Application No. ES P200930190, filed on May 20, 2009, which is hereby incorporated by reference in its entirety.
Embodiments of the present invention relate to methods and devices for establishing Call Switching (CS) connections of, for example, 64/128 Kbps for voice or data transmission in real time, through a third generation (3G) or beyond 3G network, to provide real time services such as speech, fax service, video over CS, etc.
In the context of the latest strategies followed by 3G network operators, one trend is to offer and transport all existing fixed services (supported by PSTN) over the Mobile Network as well. This meets high demand by the Business Segment of customers, for example in the SOHO (single office/home office) market.
One of these types of services that is crucial in any business portfolio is fax service. Generally, enterprise customers with heavy fax traffic can use a fax server running on a server computer equipped with one or more fax-capable modems, which support fax transmission protocol T.30 and are attached to PSTN (Public Switched Telephone Network) by fixed telephone lines usually. More recently, fax service can be provided with T.38 technology (“Fax over IP”) to transmit the signal over an IP network.
Fax service, plain old telephone service (POTS) or point of sale terminals (POS terminals are computerized devices equipped with analog modems for performing transactions by a debit/credit card) are widely used over the fixed lines by applying different protocols (T.30, T.38 or G.711, etc).
In order to support these real time services (fax, POTS, POS, etc.), the Basic Rate Interface (BRI, 2B+D, 2B1D) is used. BRI is defined in the physical layer standard 1.430 produced by the ITU as an Integrated Services Digital Network (ISDN) configuration consisting of two 64 Kbps “bearer” channels (B channels) for voice or user data and one 16 kbit/s “Delta” channel (D channel) for any combination of data, control/signalling and X.25 packet networking. Both B channels could be bonded together giving a total data rate of 128 Kbps.
In 3G (and beyond 3G) networks, different domains are established depending on the transfer mode for traffic transmission of the different services: the Circuit or Call Switching (CS) mode and Packet Switching (PS) mode. Also, several traffic classes are distinguished according to the kind of service. A radio access bearer (RAB) with determined capability defined by a series of attributes is assigned to each service. Some standard examples of linking radio bearers to services are given by the 3GPP in the Technical Specification TS 34.108 and shown in next table 1.
Note that traffic of a service such as FAX is classified as streaming and assigned to radio access bearers with a bit rate less than 128 Kbps of BRI.
Therefore, it is desirable for the Mobile Network Operators (MNOs) to offer to all the Customer Segments (especially, the SOHO) fax service or other real time services in all the situations in which MNOs serve total communications (i.e., granting data connectivity, quick activation, protected service, etc.) by using their wide area mobile networks to provide this kind of services, instead of existing fixed lines.
Disclosed embodiments allow real time fax transmission (in digital formats of Group 3 and 4 faxes) and any other real time service (data transmission in real time transactions, for instance. executed by POS devices; video over call switching; voice, etc.) to use transparently up to two 64 Kbps bearers provided by the mobile network in the Call Switching (CS) domain. These two CS connections of 64 Kbps emulate an ISDN BRI (2×64K channels) and enable to perform a real time operation as in the fixed line.
Disclosed embodiments use the radio access bearer (RAB) of 64 Kbps in uplink (UL) and 64 Kbps in downlink (DL), associated by the 3GPP TS 34.108 with traffic of conversational class such as video-call, to carry the traffic of fax and the other aforementioned real time traffic. Conversational 64/64 is currently supported by all the 3G (Access and Core) networks. Other RABs defined in the 3GPP TS 34.108 for providing 128 Kbps of transmission rate in the CS domain can be also used for this purpose (refer to table 1).
Disclosed embodiments establish the physical interface between the originating or calling terminal (a G3 or G4 fax machine, a plain old telephone, a POS device, etc.) and a device which supports this physical interface and setup the protocol conversions needed in order to carry out the fax or any other real time service transmission over the CS bearer(s).
The communication between the interface converting device and the originating terminal (a Terminal Equipment: TE) can be done through standard AT commands, typically used by computers to communicate with modems, defined in the 3GPP Technical Specification 27.007. AT commands are interchanged between a Terminal Adapter (TA), which is the physical equipment where AT command interpreter resides (for example, the user's mobile phone) and the Terminal Equipment (TE), which is the physical equipment from where applications communicate with TA using AT commands (e.g., a computer, a digital fax machine, . . . ). AT (command) stand for ATtention, this two-character abbreviation is always used to start a command line to be sent from TE to TA.
One example embodiment refers to a device for setting up CS connections to provide real time services in wide area mobile networks (supporting 3G or beyond 3G technologies), which is connectable to at least one TE capable of originating a real time transmission (fax, voice, video, etc.). The device comprises, for example:
Another embodiment deals with a method for setting up connections in CS domain of mobile networks to provide real time services (voice, fax, video over CS, . . . ). The example method comprises the following steps:
In the example case where AT commands are triggered to setup the CS bearers, the particular commands and parameters to be used are the AT+CBST and the AT+D, according to AT command parameter syntax as follows
AT+CBST command is used to select the bearer service <name> with data rate <speed>, and the connection element <ce> to be used when data calls are originated (refer 3GPP TS 22.002).
To setup the call, the AT+D command is used, as defined by ITU-T V.250 (Dial command D). V.250 dial command D lists characters that may be used in a dialling string for making a call or controlling supplementary services in accordance with 3GPP TS 22.030. Their use in GSM/UMTS is listed in this subclause, as well as new dial modifiers applicable only to GSM/UMTS are introduced. For a device supporting AT commands only, it is mandatory to support the control of supplementary services in accordance with 3GPP TS 22.030 through the dial command or through the specific supplementary service commands (+CCFC, +CLCK, etc.), where 3GPP TS 22.030 identifies the supplementary services as mandatory.
The bearer capability information included in the triggered commands also contains the information transfer capability, which is defined in ISDN to have one of two possible valid values: either UDI either RDI. UDI stands for Unrestricted Digital Information, also called 64U or 64C (“64 Clear”, the term “clear” meaning that the 64 Kbps channel is transparently or clearly carrying traffic; the information transfer rate for call traffic is set to 64 Kbps). RDI stands for Restricted Digital Information, also called 64R (“64 Restricted”). In the context of the invention, the information transfer capability is set to the information transfer capability (UDI).
In the case that it is needed to setup 128 Kbps (2×64 Kbps), respective commands with the same bearer capability information are sent from the originating and terminating parties (mobile or fixed equipment), so that a double bearer of 64 Kbps transparent can be setup in the Mobile Network.
The Core Network (CN) attempts to complete calls using the bearer capability information, in addition to the information provided by the mobile network operator (MNO). Since UDI is requested for the call establishment, the CN routes the call over facilities designated by the MNO as supporting UDI.
Conversational 64/64 UDI is supported by the Access Network and Core Network is a transparent bearer to carry the traffic, so it can well be used to transport transparently, for example, fax transmission protocol (T.30) for Group 3 and 4 between the originating and terminating fax machine. The 3G Mobile Network inter-connects the two fax machines through the normal PSTN-gateways used to connect mobile and fixed network.
One advantage of the disclosed implementation is important Bandwidth savings (around 300 Kbps per each connection) on the Radio interface, since all the overheads introduced by using IP are removed
To complete the description that is being made and with the object of assisting in a better understanding of the characteristics of the invention, in accordance with a preferred example of practical embodiment thereof, accompanying said description as an integral part thereof, is a set of drawings wherein, by way of illustration and not restrictively, the following has been represented:
FIG. 1.—It shows two different embodiments: (A) a device for setting up call switching connections for real time services connected to 3G user equipment, (B) a device for setting up call switching connections for real time services integrated into one single 3G user equipment.
FIG. 2.—It shows a message diagram representation of the method for setting up call switching connections for real time services implemented by the device shown in the
Bearer capability information element has, among many other parameters, the following options for the CS calls as defined in 3GPP TS 22.001:
When there is a FAX call from a mobile user equipment (UE) to a fixed FAX in the PSTN, it is needed to setup the CS 64K bearer in the mobile side. So, the Bearer capability has information transfer capability set to Unrestricted Digital Information. Then in the Core Network (CN), it is needed to intercept and modify this message to 3.1 kHz audio in order to convert the call to reach the external FAX in the PSTN. Then the signalling nature of the call is changed so as to enable proper end-to-end signalling inter-working. This behaviour is achieved for subscribers using compatible line by means of Intelligent Network triggers at both originating and terminating parties of the calls.
When there is a FAX call from PSTN to a User Equipment (UE) in the Mobile Network, the call is coming with a 3.1 kHz audio capability and the Core Network (CN) requires to modify this message to Unrestricted Digital Information with 64 Kbps establishment and to make the data conversion.
Once the transparent CS 64K bearer is setup in uplink as well as in downlink, a proprietary message (23) for indicating data bypass over the 64K channel is sent by the device (1). The call is normally established (24). Then, a call setup confirmation is received by the device (1) and the data of the real time service is relayed (25) by the device (1) to the Mobile Network through the mobile user equipment (UE), which performs said transmission using the 64K radio bearer previously negotiated with the Core Network (CN).
Note that in this text, the term “comprises” and its derivations (such as “comprising”, etc.) should not be understood in an excluding sense, that is, these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements, steps, etc.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200930190 | May 2009 | ES | national |
