Mobile networks using ATM switching

Details Mobile networks using ATM switching Mobile networks using ATM switching

1999-10-08

2004-07-27

Olms, Douglas (Department: 2661)

Multiplex communications

Communication over free space

Using atm as a wireles protocol

C370S310100, C370S310200

Reexamination Certificate

active

06768724

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to telecommunication networks and particularly to mobile networks using ATM (Asynchronous Transfer Mode) transfer systems. The invention also relates to the control of mobility and call control functions in ATM systems.
BACKGROUND OF THE INVENTION
Two of the current development trends in telecommunication are mobile communication and broadband networks. The term broadband typically refers to a bit rate higher than 2 Mbit/s. Narrowband usually refers to a bit rate of 64 kbit/s or lower. Bit rates from 64 kbit/s to 2 Mbit/s are sometimes referred to as wideband. Broadband networks are attractive for at least two (compatible) reasons:
1) A single broadband network bearer divided among a plurality of users, few or none of whom need the whole bandwidth alone, can offer advantages concerning flexibility and the building of transfer systems.
2) Information to be transferred on separate transfer channels possibly demand broadband channels. Users need new high-quality services, which in turn require high bit rates. Such services include e.g. video conferences, high-speed data transmission, etc. A common denominator for these services is multimedia, which combines image, voice and data into one service.
Due to its numerous strengths, ATM (Asynchronous Transfer Mode) is chosen as the transmission technique in various standardized B-ISDN (Broadband Integrated Services Digital Network) protocol structures. In this connection the term ‘transmission’ refers to the use of ATM switching and multiplexing techniques in a data link layer (i.e. an OSI Layer
2
, hereinafter referred to as an ATM layer) relaying end user traffic from a source to a destination within a network. Between the source and the destination are established virtual connections, which requires the network to have switching functions. Signalling and user information are normally conveyed by different virtual connections in an ATM layer. A virtual connection is identified in the ATM layer by a Virtual Path Identifier VPI and a Virtual Channel Identifier VCI.
In ATM information is conveyed segmented in fixed-length cells, the number of the cells in a time unit being proportional to the user's bandwidth requirements. Each 53-octet cell is divided into a 5-octet header and a 48-octet information field, as shown in FIG.
2
.
The main purpose of the header is to identify a connection number for a cell sequence providing a virtual channel for a particular call. A plural number of virtual paths, which are multiplexed in the ATM layer, can be connected to one and the same physical layer (i.e. an OSI Layer
1
), each path being identified by an 8-bit VPI at a User-to-Network Interface UNI and a 12-bit VPI at a network-node interface. Each path can comprise a plural number of virtual channels, each of which is identified by a 16-bit VCI. The header can also comprise other fields, such as a Header Error Control HEC, a Generic Flow Control GFC, a Cell Loss Priority CLP and a Payload Type PT.
The User-to-Network interface UNI between an ATM user terminal and an ATM switch (a private UNI) and between private and public ATM networks (a public UNI), together with a UNI signalling (and an ATM cell) related thereto, are defined at least in the following recommendations:
[1] ATM User-to-Network Interface Specification, version 3.1, ATM Forum, 1994;
[2] ATM User-to-Network Interface (UNI) Signalling Specification, version 4.0, ATM Forum, June 1994;
[3] ITU-T Recommendation Q.2931 (1994) Broadband Integrated Services Digital Network (B-ISDN), Digital Signalling System No. 2 (DSS 2), User-to-Network Interface (UNI) Layer 3 Specification for Basic Call/Connection Control. ITU-T.
In mobile networks, radio interfaces have conventionally been narrowband. Mobile network transmission systems have conventionally been implemented with circuit-switched connections using a star or tree network configuration. In order to increase the capacity and flexibility of transmission systems, different broadband packet switched transmission systems have also been proposed for mobile networks, e.g. in WO 9319559, WO 9400959 and EP 0366342. EP0426269 describes a mobile system in which base stations are connected via routers to ATM network switches. Virtual connections controlled by the base stations are established between the base stations through the ATN network. Elementary mobility management is based on routing tables, which are maintained at base stations and in ATM switches and updated as subscribers move. GB2268359 and EP 679042 describe an ATM-access network in which there are permanent ATM virtual connections (to speed up the call set-up) between base stations and a mobile network interface, said connections being allocated for each call separately.
A possible future development trend is that mobile systems will have a broadband radio interface. In this case the transmission system of the mobile system should also be broadband, a potential alternative being provided by the ATM technology.
A third development trend is the introduction of wireless data transmission (wireless ATM) and mobility management into ATM networks. However, a problem arising from this is that current B-ISDN and ATM standards in no way support the mobility management, subscriber authentication, call control, etc., required by mobile communication. To introduce into the ATM network such supplementary characteristics required by mobile communication would therefore seem to require considerable development and standardization of and significant changes to the existing ATM systems. The implementation of wireless ATM would thus become a slow and an expensive process.
BRIEF SUMMARY OF THE INVENTION
An object of the invention is to implement an ATM-transmission or an ATM-access network in a more flexible manner than before in mobile network architectures that conventionally use circuit-switched transmission systems.
Another object of the invention is to add wireless transmission and mobility to the ATM network, without significant changes to the existing ATM networks and standards.
An aspect of the invention is a telecommunication network, such as a mobile network, comprising mobile stations, base stations, at least one switching network element performing call control and switching, and an ATM switching function for a dynamic switching of virtual ATM transmission connections between the base stations and said at least one switching network element. The invention is characterized by said ATM switching function being arranged in said at least one switching network element and being controlled through an internal interface by a call control of the network element.
Another aspect of the invention is a wireless ATM network comprising mobile stations and at least one ATM switch to which base stations are connected through a network-to-user interface UNI. The invention is characterized by
the ATM network having at least one switching network element of another telecommunication network, such as a mobile network, to perform call control and switching control;
said switching network element being provided with an ATM switching function, which is controlled through an internal interface by the call control of the network element, for a dynamic switching of virtual ATM transmission connections between the base stations and said at least one switching network element.
A further aspect of the invention is a switching network element of a mobile network. The invention is characterized by the network element comprising an ATM switching function for a dynamic switching of virtual ATM transmission connections to base stations and by controlling the ATM switching function, through an internal interface, with a call control of the network element.
A still further aspect of the invention is a method according to claim
11
.
In the invention a network element of a telecommunication network, such as a mobile network, which in conventional telecommunication network architecture performs the switching of circuit-switched connections, is provi

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