Local service handover

Details Local service handover Local service handover

2001-11-01

2004-06-01

Pham, Chi (Department: 2663)

Multiplex communications

Communication over free space

Having a plurality of contiguous regions served by...

C370S401000

Reexamination Certificate

active

06744753

ABSTRACT:

FIELD OF THE INVENTION
The invention disclosed broadly relates to ubiquitous computing and more particularly relates to improvements in short range wireless technology.
BACKGROUND OF THE INVENTION
Short Range Wireless Systems
Short range wireless systems have a typical range of one hundred meters or less. They often combine with systems wired to the Internet to provide communication over long distances. The category of short range wireless systems includes wireless personal area networks (PANs) and wireless local area networks (LANs). They have the common feature of operating in unlicensed portions of the radio spectrum, usually either in the 2.4 GHz Industrial, Scientific, and Medical (ISM) band or the 5 GHz Unlicensed-National Information Infrastructure (U-NII) band. Wireless personal area networks use low cost, low power wireless devices that have a typical range of ten meters. The best known example of wireless personal area network technology is the Bluetooth Standard, which operates in the 2.4 GHz ISM band. It provides a peak air link speed of one Mbps and a power consumption low enough for use in personal, portable electronics such as PDAs and mobile phones. Wireless local area networks generally operate at higher peak speeds of between 10 to 100 Mbps and have a longer range, which requires greater power consumption. Wireless local area networks are typically used as wireless links from portable laptop computers to a wired LAN, via an access point (AP). Examples of wireless local area network technology include the IEEE 802.11 Wireless LAN Standard and the HiperLAN Standard, which operates in the 5 GHz U-NII band.
The Bluetooth Short Range Wireless Technology
Bluetooth is a short range radio network, originally intended as a cable replacement. It can be used to create networks of up to eight devices operating together. The Bluetooth Special Interest Group, Specification Of The Bluetooth System, Volumes 1 and 2, Core and Profiles: Version 1.1, Feb. 22, 2001, describes the principles of Bluetooth device operation and communication protocols. The devices operate in the 2.4 GHz radio band reserved for general use by Industrial, Scientific, and Medical (ISM) applications. Bluetooth devices are designed to find other Bluetooth devices within their ten meter radio communications range and to discover what services they offer, using a service discovery protocol (SDP).
The SDP searching function relies on links being established between the requesting Bluetooth device, such as a stationary access point device, and the responding Bluetooth device, such as a mobile user's device. When the mobile user's device enters within communicating range of the access point, its Link Controller layer in its transport protocol group handles the exchange of inquiry and paging packets to establish the initial link with the access point device. This process is relatively fast, typically being completed in approximately from one to five seconds. Then the Logical Link Control and Adaptation Protocol (L2CAP) layer in the transport protocol group passes the link status up to the layers in the middleware protocol group. The SDP searching function in the middleware protocol group can then be used to find out about application programs in the responding Bluetooth device that may provide desired services. The SDP searching function can require several seconds to complete, depending on the complexity of the search and the size of the device's registry.
An example application program service that can be discovered by the SDP searching function is the Wireless Application Environment (WAE) graphical user interface (GUI) function of the Wireless Application Protocol (WAP). WAP-enabled wireless devices can use a microbrowser to display content on a small screen of the device. WAP uses a combination of Internet protocols with other protocols especially modified to work with mobile devices. The Internet protocols are: Point to Point Protocol (PPP), Internet Protocol (IP), and User Datagram Protocol (UDP). The special mobile device protocols are: Wireless Transport Layer Security (WTLS), Wireless Transaction Protocol (WTP), Wireless Session Protocol (WSP), and Wireless Application Environment (WAE). It is the WAE that provides the microbrowser user interface for WAP. In order to establish a connection to send content from the requesting access point device to the WAE microbrowser of the responding user's device, each of the WAP protocol layers WTLS, WTP, WSP, and WAE must be established, which can require several more seconds to complete and possibly significant user interaction on the way.
It can be seen that if the user's mobile Bluetooth device has enough speed to travel across the communications area of the Bluetooth access point before completing downloading data from a network server, the contact with the server will be irretrievably lost.
The IEEE 802.11 Wireless LAN Standard
The IEEE 802.11 Wireless LAN Standard defines at least two different physical (PHY) specifications and one common medium access control (MAC) specification. The IEEE 802.11(a) Standard is designed for either the 2.4 GHz ISM band or the 5 GHz U-NII band, and uses orthogonal frequency division multiplexing (OFDM) to deliver up to 54 Mbps data rates. The IEEE 802.11(b) Standard is designed for the 2.4 GHz ISM band and uses direct sequence spread spectrum (DSSS) to deliver up to 11 Mbps data rates. The IEEE 802.11 Wireless LAN Standard describes two major components, the mobile station and the fixed access point (AP). IEEE 802.11 networks can be configured where the mobile stations communicate with a fixed access point. IEEE 802.11 also supports distributed activities similar those of the Bluetooth piconets. The IEEE 802.11 standard provides wireless devices with service inquiry features similar to the Bluetooth inquiry and scanning features.
In order for an IEEE 802.11 mobile station to communicate with other stations in a network, it must first find the stations. The process of finding another station is by inquiring. Active inquiry requires the inquiring station to transmit queries and invoke responses from other wireless stations in a network. In an active inquiry, the mobile station will transmit a probe request frame. If there is a network on the same channel that matches the service set identity (SSID) in the probe request frame, a station in that network will respond by sending a probe response frame to the inquiring station. The probe response includes the information necessary for the inquiring station to access a description of the network. The inquiring station will also process any other received probe response and Beacon frames. Once the inquiring station has processed any responses, or has decided there will be no responses, it may change to another channel and repeat the process. At the conclusion of the inquiry, the station has accumulated information about the networks in its vicinity. Once a station has performed an inquiry that results in one or more network descriptions, the station may choose to join one of the networks. The IEEE 802.11 Wireless LAN Standard is published in three parts as IEEE 802.11-1999; IEEE 802.11a-1999; and
IEEE
802.11b-1999, which are available from the IEEE, Inc. web site http://grouper.ieee.org/groups/802/11.
In the case of IEEE 802.11 mobile stations, if the user's mobile device has enough speed to travel across the communications area of the IEEE 802.11 access point before completing downloading data from a network server, the contact with the server will be irretrievably lost.
High Performance Radio Local Area Network (Hiperlan)
The HiperLAN standard provides a wireless LAN with a high data rate of up to 54 Mbps and a medium-range of 50 meters. HiperLAN wireless LANs provide multimedia distribution with video QoS, reserved spectrum, and good in-building propagation. There are two HiperLAN standards. HiperLAN Type 1 is a dynamic, priority driven channel access protocol similar to wireless Ethernet. HiperLAN Type 2 is reserved channel access protocol similar

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