Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-04-01
2002-04-16
Nguyen, Lee (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S063300, C455S067150, C455S426100, C455S453000, C455S509000, C455S511000, C370S352000, C370S353000
Reexamination Certificate
active
06374112
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to mobile communications, and in particular, to flexibly providing a wide variety of mobile communications services and efficiently allocating resources to support those services.
BACKGROUND OF THE INVENTION
Mobile communications have developed from first generation, analog-based mobile radio systems to second generation digital systems, such as the European Global System for Mobile communications (GSM). Current developments for a third generation of mobile radio communication include the Universal Mobile Telephone communications System (UMTS) and the IMT 2000 system. For simplicity, third generation systems are referred to simply as UMTS. In simple terms, UMTS is “communication to everyone, everywhere,” where communication also includes the provision of information using different types of media, i.e., multimedia communications.
From the user's perspective, there should be no distinction in service capability between mobile or fixed network access. Because of the widespread success of the existing GSM platform, i.e., a global “GSM footprint,” as well as the inherent upgradability and modularity of the GSM platform, there is a strong impetus to base UMTS on an “evolved” GSM platform. In fact, the present invention describes a UMTS based on an evolved GSM platform and therefore uses GSM terminology. Of course, those skilled in the art will recognize that the principles of the present invention are not limited to a GSM platform/terminology and may be implemented using other appropriate platforms.
Current mobile/cellular telecommunications networks are typically designed to connect and function with Public Switched Telephone Networks (PSTNs) and Integrated Services Digital Networks (ISDNs). Both of these networks are circuit-switched networks (rather than packet-switched) and handle relatively narrow bandwidth traffic. However, packet-switched networks, such as the Internet, are very much in demand and handle much wider bandwidth traffic than circuit-switched networks. While wireline communication terminals, e.g., personal computers, are capable of utilizing the wider packet-switched network bandwidth, wireless mobile radio terminals are at a considerable disadvantage because of the limited bandwidth of the radio/air interface that separates the mobile terminals from packet-switched networks.
Mobile terminals are currently limited in the data rates for data communications services such as facsimile, electronic mail, and Internet. While it is feasible perhaps to provide some slow-scan video and picture transfer at this limited rate over the radio air interface at this limited rate, as long as demands on quality are not too high, the expectations regarding real time use of the Internet are a more difficult challenge. The demand is growing for higher data transfer speeds in order the “surf the net” using mobile terminals with fast access to text, images, and sound. This multimedia application demands high peak bit rates in short bursts while the information is downloaded to the mobile terminal. Another challenging multimedia, mobile terminal application is simultaneous voice and data, e.g., PC application sharing or shared whiteboard. Although this latter type of multimedia application does not require particularly high bit rates, it does require real time, continuous operation because of the voice content. A demanding circuit-switched application (rather than packet-switched as in the Internet application) requiring relatively high bit rates is video conferencing. In order for mobile video conferencing to become practical, the amount of user bandwidth required must be reduced to a minimum without sacrificing image quality.
GSM already meets some of the requirements for UMTS. For example, two new service classes are under development for GSM to expand the current user data rate: High Speed Circuit Switched Data (HSCSD) and General Packet Radio Service (GPRS). Both services are designed to integrate with the current GSM system. HSCSD bearer services bundle up eight Time Division Multiple Access (TDMA) time slots within a 200 kHz GSM carrier to create a higher bandwidth channel. In other words, a 64 kbps circuit switched bearer channel uses all available TDMA slots. HSCSD is also being developed to provide bandwidth on demand at variable data rates. GPRS is a packet switching technique that employs reduced channel coding to achieve a net bit rate of 14.4 kbps per time slot providing a maximum throughput rate of 115 kbps. It is more suited to handling “bursty” traffic such as the infrequent transmission of e-mail messages, Internet information, and other data. Because GPRS is a packet switching service, it only requires a channel when data is being sent thereby enabling the frequency spectrum to be more efficiently allocated across voice and data calls and allowing channels to be shared between several users simultaneously.
However, one area of weakness for GSM is narrowband radio access. A UMTS Wideband-Code Division Multiple Access (WCDMA) radio access network provides wireless access at very high data rates and supports enhanced bearer services not realistically attainable with the first and second generation mobile communication systems. WCDMA currently supports 5 MHz-15 MHz, and in the future, promises an even greater bandwidth. In addition to wide bandwidth, WCDMA also improves the quality of service by providing robust operation in fading environments and transparent (“soft”) handoffs between base stations. Multiplath fading is used to advantage to enhance quality, i.e., using a RAKE receiver and improved signal processing techniques, contrasted in narrowband systems where fading substantially degrades signal quality.
In the present invention, a UMTS Terrestrial Radio Access Network (UTRAN) responds to radio access bearer service requests with flexible and efficient allocation of resources needed to support a communication with a mobile radio. The UTRAN includes plural base stations for communicating with mobile radios over a radio air interface using radio channel resources allocated by a radio network controller connected to the base stations. External network service nodes that interface with external networks communicate with mobiles via the UTRAN. When one of the service nodes requires communication with a mobile radio, the service node requests a radio access bearer from the UTRAN rather than a specific radio channel resource. A radio access bearer is a logical connection with the mobile station through the UTRAN and over the radio air interface and corresponds to a single data stream. For example, one radio access bearer may support a speech connection, another bearer may support a video connection, and a third bearer may support a data packet connection. Each radio access bearer is associated with quality of service (QoS) parameters describing how the UTRAN should handle the data stream. Examples of quality of service parameters include data rate, variability of data rate, amount and variability of delay, guaranteed vs. best effort delivery, error rate, etc.
The radio access bearers are dynamically assigned to UTRAN transport and radio channel resources by the UTRAN. The radio access bearer service and the UTRAN isolate the details of transport and radio resource allocation handling as well as details of radio control, e.g., soft handoff. The UTRAN approach is different from traditional approaches where an external network and/or an external network service node is involved in the details of requesting, allocating, and controlling specific radio connections to and from the mobile radio. Instead, the external network service node only needs to request a radio access bearer service over a RAN interface to the UTRAN along with a specific quality of service for a communication to a specific mobile radio. The UTRAN provides the requested service at the requested quality of service (if possible).
Plural radio access bearers may be established and released independently to one mobile radio including bearers f
Wallentin Bo S. P.
Widegren Ina
Willars Per H. A.
Nguyen Lee
Nixon & Vanderhye P.C.
Telefonaktiebolaget LM Ericsson (publ)
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