Multiplex communications – Communication over free space
Reexamination Certificate
1998-10-13
2004-04-13
Vanderpuye, Kenneth (Department: 2732)
Multiplex communications
Communication over free space
C370S328000, C709S203000
Reexamination Certificate
active
06721288
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to wireless networks, and more particularly, to operation of wireless mobile devices during unavailability of wireless networks.
2. Description of the Related Art
Wireless networks are often used to transmit messages from one location in a network to a destination location in the network. These messages contain data to be supplied to the destination location. More specifically, the messages include a header portion and a data portion. The header portion includes an address of the destination location, and the data portion contains data. The destination location is, for example, a mobile device or a server. A mobile device typically interacts with wireless networks to receive various types of notifications or to request and receive data from another network to which the wireless network is connected.
FIG. 1
is a block diagram of a conventional wireless communication system
10
. The wireless communication system
10
includes a server
12
, a wireless network
14
, and mobile devices
16
. There are n mobile devices
16
-
1
through
16
-n. The server
12
is typically a computer system that operates to send and receive messages to and from the mobile devices
16
. The messages are often blocks of data that are to be transmitted to the mobile device
16
. As examples, the data can pertain to various types of notifications, electronic mail, news data, configuration information, data files, library files, program files, etc. The messages can also be requests for information (e.g., certain data) that are transmitted from the mobile devices
16
to the server
12
. The server
12
may also connect to other wired or wireless networks to receive messages from or forward messages to other computer systems. As an example, the server
12
can be connected to the Internet. For example, the server
12
can be a proxy server (or link server) coupled to the Internet or a network gateway coupled to a network. The tremendous growth of the Internet in recent years has fueled the need to provide mobile devices such as mobile telephones, personal digital assistants (PDAs) and the like with access to information and services available on the Internet.
The wireless network
14
typically uses radio transmissions to communicate with the mobile devices
16
. The wireless network
14
can use a variety of different networks and communication protocols. Examples of wireless networks include Cellular Digital Packet Data (CDPD), Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA) and Time Division Multiple Access (TDMA) to name a few, and each of these wireless networks has different data transfer characteristics such as latency, bandwidth, protocols and connection methods. As examples, protocols can be Internet Protocol (IP), Short Messaging System (SMS) and Unstructured Supplementary Service Data (USSD), and connection methods can include packet switched or circuit switched.
As an example, a message to be sent by the server
12
to the mobile device
16
-
2
would contain an address that particularly identifies the mobile device
16
-
2
. The message is then provided by the server
12
to the wireless network
14
. For example, one wireless data network is a packet switched network using a Small Message Server Center (SMSC) which has a relatively small packet size (e.g., 140 bytes). The wireless network
14
causes the message to be properly routed to the mobile device
16
-
2
(i.e., in accordance with the address). The transmission between the wireless network
14
and mobile device
16
-
2
is wireless. The mobile device
16
-
2
receives the message that has been transmitted to the wireless network
14
. The mobile device
16
-
2
can then store the message and perform predetermined processing actions such as, for example, notifying a user of the mobile device
16
-
2
of the reception of the message.
In some wireless networks, the server and the mobile devices can be connected by two or more channels. In one case, the server and mobile devices can be connected over a one-way data channel and a two-way data channel. A representative network (e.g., GSM) having such characteristics can use a Short Message Service Center (SMSC) to provide the one-way data channel and an Interworking Function (IFW) to provide the two-way data channel. In such a network, the one-way data channel is often considered a narrowband channel and the two-way data channel is often considered a wideband channel. As an example, the narrowband channel can transfer data at a rate of about 400 bits per second (bps), while the wideband channel can transfer data at a rate of at least 14400 bps. It is thus not uncommon that a server and a mobile device be connected (or connectable) by both a two-way channel and a one-way channel. Typically, the server and the client will decide to use either or both of the channels depending on the urgency of the data, the cost willing to incur, etc. Use of a two-way channel often causes the mobile device to incur charges (i.e., fees) from a carrier that provides the service to the mobile device. In contrast, use of a one-way, narrowband channel is often available at no cost or at a fixed cost regardless of usage.
One problem with the conventional wireless communication systems is that the operation of mobile devices are very much dependent on availability of their wireless network. In other words, when the wireless network is unavailable, the mobile devices may stop processing user inputs as they wait for a response from a remote server via the wireless network. Unavailability of a wireless network can result from a user of a mobile device exceeding their geographic range of coverage. Unavailability also effectively results from a wireless network having high latencies or a wireless network having sporadic connectivity. Because of the dependency of the operation of mobile devices on the availability of wireless networks, mobile devices often have to wait for resources from a remote server.
Mobile devices are often provided with cache memories that temporarily store previously requested and obtained resources from remote servers. A cache memory is helpful in reducing the dependency of mobile devices on network availability. However, the cache memory is only helpful when the newly requested resource happens to reside in the cache memory. Hence, if the newly requested resource was not previously requested, then the newly requested resource would not be stored in the cache memory. Also, even it the newly requested resource were at one point in time stored in the cache memory, a reclamation or clean-up algorithm could have removed it from the cache memory to provide space for newer requested resources.
Another problem with the conventional wireless communication systems is that the dominating application model has a synchronous nature. The synchronous nature causes the application to wait for responses to requests to remote servers (unless satisfied by the cache memory). The wait times are unacceptably long when the wireless network is unavailable to the mobile devices.
One popular application is a network browser that is used on mobile devices to browse a network such as the Internet. Such as network browser is known as a web browser. The network browser is often requesting resources from remote servers over the wireless network. Hence, network browsers are particularly sensitive to network unavailability (e.g., due to out of coverage, high latencies, or sporadic connectivity). Consequently, it is common for network unavailability to induce significant waits for the users of network browsers on mobile devices.
Thus, there is a need for techniques to reduce delays faced by users of mobile devices due to unavailability of wireless networks.
SUMMARY OF THE INVENTION
Broadly speaking, the invention relates to improved techniques for reducing delays faced by users of mobile devices due to unavailability of wireless networks. The invention has at least three aspects that facilitate the reductio
Boyle Stephen S.
King Peter F.
Martin, Jr. Bruce K.
Schwartz Bruce V.
Stein Lawrence
Beyer Weaver & Thomas LLP
Openwave Systems Inc.
Vanderpuye Kenneth
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