Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-06-26
2001-02-06
Feild, Joseph H. (Department: 2776)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S471000
Reexamination Certificate
active
06185208
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to wireless networks, and more particularly, to transmitting messages over 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 header portion also indicates the size of the message. The destination location is, for example, a mobile device.
A wireless network, however, has a pre-defined or maximum message size that it is able to transmit efficiently through the wireless network. For example, one common wireless network, such as Short Messaging System (SMS) and Unstructured Supplementary Service Data (USSD), has a maximum size of 140 bytes. When a message to be transmitted has a size greater than the maximum message size for the wireless network, the message must be fragmented prior to transmission. More particularly, during fragmentation, the message is divided into smaller fragments or sub-messages. Each of the fragments or sub-messages has a size that is smaller than or equal to the maximum message size. After the fragments or sub-messages are formed, they are transmitted in order to the destination location.
Although the fragments or sub-messages are sent in order, the order in which they are received at the destination location is not always in sequential order. Each fragment can take seconds, minutes or hours to reach the destination location depending on the network traffic. As a result, each of the fragments or sub-messages includes (within the header portion) a sequence number that identifies the relative order of the particular fragment or sub-message within the message. The sequence number assists the destination location in reassembling the message from the message fragments or sub-elements.
Additionally, multiple messages may be concurrently received at a given destination location. The destination location needs some way to keep the fragments or sub-messages for the multiple messages separate. Conventionally, all the fragments or sub-messages for a given message include a particular reference number. In other words, each of the fragments or sub-messages for a given message will include a reference number of the same value in their header portion. The reference number thus allows the destination location to separate those fragments and sub-messages of different messages so that the multiple messages can be properly reassembled at the destination location.
Conventionally, the management and utilization of the reference numbers has some problems. With a wireless network, it is common that there are a large number of subscribers that can serve as destination locations. One conventional approach is to assign a unique reference number to each subscriber on the wireless network. However, with so many subscribers, the amount of data storage needed at a server (e.g., message server) just for all the reference numbers is large and costly. As an example, a wireless network with one million subscribers would need to store one million reference numbers. The large amount of data storage required with this approach is a problem.
Another conventional approach uses a single, large reference number for all transmission from a source location. For example, the large reference number can be 64 bits or more. The reference number needs to be large to minimize the likelihood that an overlap in reference number to the same destination location could occur. The problem with this approach is that the large size of the reference number consumes a significant portion of the bandwidth of each fragment or sub-message being transmitted.
Thus, there is a need for improved management and utilization of reference numbers for use in transmitting messages.
SUMMARY OF THE INVENTION
Broadly speaking, the invention relates to improved techniques for providing reference numbers for purposes of fragmenting a message for transmission over a network (e.g., a wireless data network) supporting only a limited size message. The reference numbers for the fragmented messages are shared by groups of destinations (e.g., subscribers or mobile devices). As a result, the number of reference numbers to be stored is small compared to the number of possible destinations, and the size of the reference numbers themselves is also kept small. The number of groupings and the size of the reference numbers can also be adjusted to fit system objectives.
The invention can be implemented in numerous ways, including as a method, a computer readable medium, an apparatus, and a system. Several embodiments of the invention are discussed below.
As a method for transmitting fragments of a message, an embodiment of the invention includes the operations of: receiving a message to be transmitted; obtaining a message size for the message; determining whether the message size is greater than a predetermined maximum size, determining a group number for the message; obtaining a reference number for the message based on the group number; fragmenting the message to form message fragments when the message size is determined to be greater than the predetermined maximum size, with each of the message fragments including the reference number; and thereafter transmitting the message fragments.
As a computer readable medium storing computer program code for transmitting fragments of a message, an embodiment of the invention includes: computer program code for receiving a message to be transmitted; computer program code for determining a group number for the message; computer program code for obtaining a reference number for the message based on the group number; computer program code for fragmenting the message to form message fragments, with each of the message fragments including the reference number; and computer program code for transmitting the message fragments.
As an apparatus for transmitting messages through a wireless data network to mobile devices, an embodiment of the invention includes: a message buffer, a group determination unit, a reference number table, a fragmentation unit, and a message transmission unit. The message buffer for storing a message to be transmitted to a particular mobile device. The group determination unit determines a group number for the message, where the group number identifies a group associated with the particular mobile device. The reference number table associates a different one of a plurality of reference numbers with each of the groups. The fragmentation unit receives a particular reference number from said reference number table based on the group number for the message and receives the message from the message buffer. The fragmentation unit then operates to fragment the message into sub-messages, with each of the sub-messages including the particular reference number and a portion of the message. The message transmission unit thereafter transmits the sub-messages to the particular mobile device.
The advantages of the invention are numerous. One advantage of the invention is that transmission of the appropriate reference number with each fragment or sub-message does not severely impinge upon the available transmission bandwidth because the reference number can be kept relatively small. Another advantage of the invention is that a server for receiving messages to be transmitted need not store large amount of data because only reference numbers for a limited number of groups need be stored. Still another advantage of the invention is that the size of the reference numbers and the number of groups which share reference numbers can both be adjusted as desired to meet system objectives.
Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, ill
Beyer Weaver & Thomas LLP
Feild Joseph H.
Phone.com, Inc.
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