Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1997-12-08
2001-03-06
Tsang, Fan (Department: 2746)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S466000, C455S442000
Reexamination Certificate
active
06198929
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates to communications. More particularly, the present invention relates to a system and method for performing mobile switching center initiated service negotiation.
II. Description of the Related Art
The use of code division multiple access (CDMA) modulation techniques is one of several techniques for facilitating communications in which a large number of system users are present. Although other techniques such as time division multiple access (TDMA), frequency division multiple access (FDMA), and amplitude modulation (AM) schemes such as amplitude companded single sideband (ACSSB) are known, CDMA has significant advantages over these other techniques. The use of CDMA techniques in a multiple access communication system is disclosed in U.S. Pat. No. 4,901,307, entitled “SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS,” assigned to the assignee of the present invention and incorporated by reference herein.
In the wireless CDMA system, a large number of wireless subscriber units, each having a transceiver, communicates through satellite repeaters or terrestrial stations which are also referred to as cells. Each cell includes a physical plant called a base station. A cell covers a limited geographic area and routes calls carried over subscriber units to and from a telecommunication network via a mobile switching center. When a subscriber moves into the geographic area of a new cell, the routing of that subscriber's call may be eventually made through the new cell by a process called a “handoff.”
A subscriber unit transmits a signal that is received by a base station. The signal is then relayed to a mobile switching center which in turn routes the signal to the public switched telephone network and to telephone lines or other subscriber units. Similarly, a signal may be transmitted from the public switched telephone network to a subscriber unit via a base station and a mobile switching center. The communications channel allocated for communication of information between the subscriber unit and the base station is called the traffic channel.
The interface between the subscriber unit and the base station is referred to as the air interface. The telecommunications industry association (TIA) has provided a standard for CDMA call processing on the air interface entitled “IS-95 Mobile Station—Base Station Compatibility Standard for Dual Mode Wideband Spread Spectrum Cellular System.” Addendum to IS-95 are provided as Telecommunications Service Bulletins (TSB). The standard IS-95+TSB74 includes provisions for service negotiation on the air interface and is incorporated herein by reference. The interface between the base station and the mobile switching center is referred to as the A interface. The TIA has provided for call processing on the A interface through the standard provided in “IS-634 Mobile Switching Center—Base Station Interface for Public 800 MHz,” which is also incorporated herein by reference. IS-95-A and IS-634 both define the messages and signals that are sent on their respective interfaces for the operation of a CDMA wireless system.
The call flow in a CDMA system requires processing on both the air interface and the A interface. The successful progression of a call requires that the proper messages and signals are sent at the right times on both the air interface and the A interface. The IS-634 standard is being developed to provide for call processing on the A interface. A number of problems and deficiencies are present in IS-634 which currently does not support some of the necessary operations on the A interface.
One deficiency in IS-634 is in the handling of the delivery of Short Message Service (SMS) messages by the mobile switching center. The Short Message Service provides for the transfer of SMS messages between a subscriber station and a Message Center. The mobile switching center and the base station provide a conduit for the messages between the message center and the subscriber station. Generally, SMS messages are messages associated with services subscribed to by a user. For example, a user may subscribe to a “stock quotes” service. The user will then periodically receive the quotes in the form of SMS message. SMS messages may be displayed as text messages on the subscriber unit. The SMS messages are sent from the mobile switching center to a base station, which in turn transmits the SMS messages to a subscriber unit. The base station may transmit the SMS messages to the subscriber unit on the paging channel or the traffic channel.
A problem arises when a new call comes in for the subscriber unit while the subscriber unit is receiving SMS messages on the traffic channel. Since the traffic channel is already occupied for delivery of SMS messages, the only options available to the mobile switching center are to either provide a busy signal to the calling party, or drop the SMS call and reestablish the traffic channel to deliver the new call. Neither option is very desirable. This deficiency is recognized and solved by the present invention in the manner described below.
SUMMARY OF THE INVENTION
The present invention is a system and method for providing improved messaging on the interface between a mobile switching center and a base station, also known as the A interface, of a wireless communication system. The present invention recognizes that the A interface, as previously defined by the IS-634 standard, does not properly handle the delivery of Short Message Service (SMS) messages by the mobile switching center under certain circumstances. In situations where a new call arrives for a subscriber unit while an SMS message is being transmitted to the subscriber unit on the traffic channel, the mobile switching center has two options under current procedures. The mobile switching center may either provide a busy signal to the calling party or drop the SMS message delivery and reestablish the traffic channel to deliver the new call. The present invention recognizes that improvements are needed for the A interface to reliably handle the delivery of SMS messages when a new call arrives. For example, a voice call may arrive for the subscriber unit while it is receiving SMS messages. Mobile switching center initiated service negotiation is introduced on the A interface to provide the improvements.
In a wireless communication system, service negotiation is the process by which a subscriber unit negotiates with the network to establish the air interface configuration for different wireless services. This configuration includes the forward and reverse communication rates, the forward and reverse framing formats (multiplex option), and services associated with different logical connections (service options). Service options refer to the service capabilities of the system, and may be applications such as voice, data, facsimile, or SMS. Presently, service negotiation is defined on the air interface to permit service negotiation between the subscriber unit and the base station. The present invention introduces service negotiation on the A interface to allow for mobile switching center initiated service negotiation, whereby the mobile switching center instructs the base station to initiate service negotiation with the subscriber unit over the air interface.
In accordance with the present invention, while a subscriber unit is receiving an SMS message on the traffic channel, if a new call arrives for the subscriber unit, the mobile switching center initiates service negotiation to allow delivery of the new call to the mobile station without dropping the delivery of the SMS message. The service negotiation will establish a new service configuration for the subscriber unit. For example, a voice call may arrive while an SMS call is in progress. In one embodiment, the new service configuration sets the primary service option to be voice, and the secondary service option to be SMS. Thus, voice from the new call and SMS messages are multiplexed, and
Krishnamurthi Rajeev
Mohanty Bibhu P.
Quick, Jr. Roy F.
Beladi S. Hossain
Qualcomm Inc.
Rouse Thomas R.
Sobutka Philip J.
Tsang Fan
LandOfFree
System and method for mobile switching center initiated... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System and method for mobile switching center initiated..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System and method for mobile switching center initiated... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2492249