Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
2000-01-10
2003-11-25
Marcelo, Melvin (Department: 2663)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C455S556200
Reexamination Certificate
active
06654360
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The current invention relates to wireless communications. More particularly, the present invention relates to an improved method and system for providing dormant mode wireless packet data services.
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. Other multiple access communication system techniques, such as time division multiple access (TDMA), frequency division multiple access (FDMA) and AM modulation schemes such as amplitude companded single sideband (ACSSB) are known in the art. These techniques have been standardized to facilitate interoperation between equipment manufactured by different companies. Code division multiple access communications systems have been standardized in the United States in Telecommunications Industry Association TIA/EIA/IS-95-B, entitled “MOBILE STATION-BASE STATION COMPATIBILITY STANDARD FOR DUAL-MODE WIDEBAND SPREAD SPECTRUM CELLULAR SYSTEMS”, incorporated by reference herein, and hereinafter referred to as IS-95. In addition, a new standard for Code division multiple access communications systems has been proposed in the United States in Telecommunications Industry Association PN-4431 and published as TIA/EIA/IS-2000-5, entitled “UPPER LAYER (LAYER 3) SIGNALING STANDARD FOR IS-2000 SPREAD SPECTRUM SYSTEMS”, dated Jul. 11, 1999, incorporated by reference herein, and hereinafter referred to as IS-2000.
The International Telecommunications Union recently requested the submission of proposed methods for providing high rate data and high-quality speech services over wireless communication channels. A first of these proposals was issued by the Telecommunications Industry Association, entitled “The IS-2000 ITU-R RTT Candidate Submission.” A second of these proposals was issued by the European Telecommunications Standards Institute (ETSI), entitled “The ETSI UMTS Terrestrial Radio Access (UTRA) ITU-R RTT Candidate Submission”, also known as “wideband CDMA” and hereinafter referred to as W-CDMA. A third proposal was submitted by U.S. TG 8/1 entitled “The UWC-136 Candidate Submission”, hereinafter referred to as EDGE. The contents of these submissions is public record and is well known in the art.
IS-95 was originally optimized for transmission of variable-rate voice frames. Subsequent standards have built on the standard to support a variety of additional non-voice services including packet data services. One such set of packet data services was standardized in the United States in Telecommunications Industry Association TIA/EIA/IS-707-A, entitled “Data Service Options for Spread Spectrum Systems”, incorporated by reference herein, and hereafter referred to as IS-707.
IS-707 describes techniques used to provide support for sending Internet Protocol (IP) packets through an IS-95 wireless network. A remote network node such as a laptop computer connected to a packet-data-capable cellular phone accesses the Internet through a wireless network in accordance with the IS-707 standard. The laptop computer typically negotiates a dynamic IP address with an interworking function (IWF) in the wireless network, also sometimes called a Packet Data Serving Node (PDSN). Negotiation of a dynamic IP address typically is performed in accordance with the well known Point-to-Point Protocol (PPP). For the duration of the packet data session between the IWF and the remote network node, the PPP state of the remote network node is stored in the IWF.
This IP address is assigned from a pool of addresses controlled by the wireless network. The laptop computer then uses this negotiated IP address to access Internet resources such as e-mail servers and web sites. Packets sent back to the laptop computer by the Internet are addressed to the assigned dynamic IP address and therefore routed to the PDSN or the wireless network.
As the IS-95 standard was optimized for voice service, it has some “circuit-switched” characteristics that are not ideal for the generally bursty nature of IP data traffic. IS-707 provides a method of establishing a “packet data call” through which a subscriber station may route packets of data (usually IP datagrams) through an IS-95 wireless network to the Internet. Once established, a packet data call remains active whether or not it is being used to transport packets. For example, a packet data call established in a packet data session to download a web page may remain active long after the download transfer is complete. Such an active packet data call consumes valuable wireless channel resources that would otherwise be available for other calls. To prevent excessive waste of wireless channel resources in idle packet data calls, many existing packet data service implementations tear down packet data calls after a period of inactivity (lack of packet traffic). Some implementations use an “inactivity timer,” the expiration of which causes the wireless system to drop the packet data call.
Some wireless networks destroy the network state of a remote network node as soon as a packet data call is dropped. When this happens, the dynamic IP address previously assigned to the dropped call is eventually freed up for use by other remote network nodes. This is generally allowable because most mobile networking applications such as retrieving e-mail and web page access are transaction-based. In other words, the laptop computer makes a request for information, and then receives the requested information from the network. The network does not generally initiate an information exchange with the remote network node. If the remote network node (laptop computer) initiates another access after its packet data call has dropped, it renegotiates its dynamic IP address with the wireless network's PDSN. The IP address negotiation process takes extra bandwidth and causes delays in the wireless channel that appear as network “sluggishness” to the laptop computer user.
In order to avoid unnecessarily renegotiating dynamic IP addresses, and to allow more efficient use of wireless channel resources, wireless network implementations support “dormant mode” operation. After the expiration of the inactivity timer, the wireless system brings down the packet data call, but preserves the network state of the remote network node. The connection that exists between the laptop computer and the wireless system in the absence of an active packet data call is referred to as dormant. The next time the remote network node wishes to access the packet data network, it causes another packet data call to be established, but does not need to renegotiate its dynamic IP address and PPP state. Reusing the previously negotiated IP address and PPP state saves bandwidth that would otherwise be consumed by packet data session renegotiations, thereby reducing the perceived sluggishness of the network access.
Because of the inherent complexities associated with dormant mode packet data implementations, wireless carriers have been slow to adopt dormant mode implementations of packet data services. For this reason, the development and debugging of dormant mode protocols has not advanced as quickly as possible. As wireless packet data services become more popular, and as its customers become more sophisticated, the remaining traps and pitfalls associated with designing protocols for providing dormant mode packet data services will have to be navigated.
SUMMARY OF THE INVENTION
Embodiments of the present invention may be used to resolve such conflicts as can occur when a remote network node that communicates with a packet data network through a wireless network is physically disconnected from the wireless network. A remote network node can be a laptop computer connected to a wireless subscriber station or can be a network services client such as a web microbrowser within the subscriber station. Web microbrowsers such as those that use the Wireless Applications Protocol (WAP) are well known in
Baker Kent
Kwoh Jasper
Marcelo Melvin
Qualcomm Incorporated
Wadsworth Philip
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