Telecommunications – Radiotelephone system – Special service
Reexamination Certificate
2001-03-08
2004-08-10
Tsang, Fan (Department: 2645)
Telecommunications
Radiotelephone system
Special service
C455S464000, C455S564000, C379S355010
Reexamination Certificate
active
06775538
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the handling of dialled digits in a wireless telecommunications system, and more particularly to a digit handling system and method for a subscriber terminal of a wireless telecommunications system.
2. Description of the Prior Art
In a typical wireless telecommunications system, a subscriber terminal (ST) may be located at a subscriber's premises for handling calls to and from that subscriber. One or more lines may be provided from the subscriber terminal for supporting one or more items of telecommunications equipment located at the subscriber's premises. Further, a central terminal may be provided for controlling a number of subscriber terminals, and in particular for managing calls between a subscriber terminal and other components of a wireless telecommunications network.
Each subscriber terminal communicates with the central terminal via a radio resource. In accordance with known techniques, multiple communication channels may be arranged to utilise the radio resource for the transmission of signals to and from the subscriber terminal. For example, in a “Code Division Multiple Access” (CDMA) system, a radio resource consisting of a particular frequency channel may be partitioned by applying different orthogonal codes to signals to be transmitted on that frequency channel. Signals to which an orthogonal code has been applied can be considered as being transmitted over a corresponding orthogonal communication channel utilising the particular frequency channel. Similarly, in a “Time Division Multiple Access” (TDMA) system, a radio resource consisting of a particular frequency channel can be partitioned in the time domain, such that a number of different signals can be transmitted in different time slots, the time slots forming multiple communication channels utilising the radio resource. As another example, in a “Frequency Division Multiple Access” (FDMA) system, a radio resource consisting of a band of frequencies may be partitioned to form a number of communication channels at particular frequencies, thereby enabling multiple signals to be transmitted over the radio resource.
It is desirable that the item of telecommunications equipment connected to a subscriber terminal is able to behave as though it were connected via a standard wired connection with an exchange (for example, a public switched telephone network (PSTN)), and in particular that the end user does not have to operate the item of telecommunications equipment any differently than he/she would operate the item of telecommunications equipment were it connected directly by a wired connection with the exchange.
In a typical wired system, if a user wishes to make an outgoing call, he/she would cause the item of telecommunications equipment to enter an off-hook state, for example by lifting the handset, the off-hook state would be detected by the exchange, and a real dial tone would then be provided from the exchange to the item of telecommunications equipment. Once the user receives the dial tone, he/she would then be able to enter dialled digits for the destination telephone number, and these would be routed straight through to the exchange.
In current versions of the above described wireless telecommunications system, a similar sequence of events occurs at the item of telecommunications equipment. Hence, when the item of telecommunications equipment enters an off-hook state, this will cause the wireless telecommunications system to establish a link to the exchange including the provision of a communication channel over the radio resource between the central terminal and the subscriber terminal. Once the link is established, the real dial tone is then generated by the exchange, and provided to the item of telecommunications equipment, whereafter the user can enter dialled digits in the usual manner, which are routed straight through to the exchange.
Whilst the above approach enables the item of telecommunications equipment to be operated in an identical manner to that in which it would be operated were the item of telecommunications equipment connected to a conventional wired link, there can be a detectable delay between the item of telecommunications equipment going off-hook and the user being provided with the real dial tone, due to the time taken to establish the link with the exchange via a communication channel of the radio resource. This issue is particularly a concern when the system is operated in a Demand Assignment mode, in which a larger number of STs are associated with the central terminal than the number of traffic-bearing communication channels available on the radio resource. In such a Demand Assignment mode, since a particular ST is not directly associated with a particular communication channel, it typically takes slightly longer to establish the wireless link, due to the extra step of determining an available communication channel over which to place a call.
Accordingly, it would be desirable to provide at technique for more efficiently establishing a call from an item of telecommunications equipment connected to a subscriber terminal, whilst still enabling the item of telecommunications equipment to be operated as though it were connected to a wired network.
SUMMARY OF THE INVENTION
Viewed from a first aspect, the present invention provides a digit handling system for a subscriber terminal of a wireless telecommunications system, the subscriber terminal being arranged to have an item of telecommunications equipment connected thereto and being connectable to a central terminal of the wireless telecommunications system via a radio resource to enable a call to be routed between the item of telecommunications equipment and an exchange coupled to the central terminal, the digit handling system comprising: a detector for detecting when the item of telecommunications equipment enters an off-hook state; a dial tone generator for generating a fake dial tone to the item of telecommunications equipment upon detection of the off-hook state; a radio manager, responsive to detection of the off-hook state, for seeking acquisition of a communication channel of the radio resource over which to pass call data; a switching element for controlling the routing of digits through the subscriber terminal, the switching element being arranged to pass to a storage digits received from the item of telecommunications equipment following the detection of the off-hook state; a digit regenerator, responsive to an indication that the communication channel has been acquired, for regenerating each digit stored in the storage and outputting the regenerated digits over the radio resource to the central terminal; the switching element being arranged, upon determination that the storage contains no further digits, to route any further digits received from the item of telecommunications equipment for output over the radio resource to the central terminal without being stored in the storage.
In accordance with the present invention, upon detection of the item of telecommunications equipment entering an off-hook state, a fake dial tone is provided to the item of telecommunications equipment whilst a radio manager seeks acquisition of a communication channel of the radio resource. Since a dial tone has been provided to the item of telecommunications equipment, the user is able to dial digits for the destination telephone number even though the actual link has not yet been established.
Since this approach enables a user to start dialling digits before the link has actually been established, a switching element is provided to pass to a storage any digits received from the item of telecommunications equipment following generation of the fake dial tone. This happens entirely transparently to the end user.
Once the communication channel has been acquired, a digit regenerator then regenerates each digit stored in the storage and outputs the regenerated digits over the radio resource to the central terminal, for forwarding on to the exc
Forbes Nicholas John David
Lamkin Richard Mortimer
Airspan Networks Inc.
Escalante Ovidio
Haynes Mark A.
Haynes Beffel & Wolfeld LLP
Tsang Fan
LandOfFree
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