Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
2000-06-05
2003-02-04
Le, Thanh Cong (Department: 2684)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S507000
Reexamination Certificate
active
06516192
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to communicating information including data over one or more selected network channels, particularly where such a communication involves a mobile unit.
BACKGROUND OF THE INVENTION
A number of communication networks are currently utilized in transmitting information including voice and data. Different network channels include CDPD (cellular digital packet data), satellite, SMR (specialized mobile radio), FM-subcarrier, DAB (digital audio broadcast), infrared and two-way messaging. The network channel that is accessed for information transfer depends on its availability in the geographic region of interest.
However, these numerous and quality-diverse communication links available for use in different geographic regions engender a new set of problems that must be faced. Chief among these relates to the reliability of the link or links that might be utilized for a predetermined communications application, particularly where the information transfer involves a mobile unit, whose position changes during the transfer. Unlike communication systems that typify the prior art in which the reliability or stability of a communication link is virtually taken for granted, the present invention involves network channels that, dependin n the conditions, can experience inconsistencies or discontinuities during the particular information transfer.
In connection with addressing these reliability issues, the inventors of the present invention have identified additional parameters as being germane to the process for selecting among different network channels for the transfer of information. These parameters include the bandwidth of the available channel and parameters related to the quality and/or quantity of the information or data being transferred, such as packet loss, packet latency and packet jitter. Bandwidth refers to the information transfer capacity of the channel and is definable in terms of a transfer rate, such as bits/second. Packet loss relates to the number of packets that are lost as a function of the number of packets that are received. Packet latency refers to the typical or average one-direction or end-to-end packet transfer time. Packet jitter refers to the variation in inter-packet receive times. Important additional factors or parameters to be taken into account as part of the network channel selection process relate to the cost of transfer including factors such as the network channel cost per packet and any channel setup cost. In view of these many parameters that can be considered when a channel is selected, the selection process for obtaining a desired or optimum network channel can be a complicated task.
The channel selection process is made more complicated and difficult when the transmitter and/or receiver of the transferred information is part of a mobile unit. In such a case, because of the movement of the mobile unit, such as a vehicle, a presently accessed network channel may no longer be available for use because of the new geographic position of the mobile unit. That is, the presently utilized network channel may not be available in the new location of the mobile unit. The network channel selection process is rendered even more complicated when, due to the different geographic position of the mobile unit, a previously unavailable channel is now available to the mobile unit. This previously unavailable channel may be more desirable for the information transfer that is currently under way.
SUMMARY OF THE INVENTION
In accordance with the present invention, a system is provided for selecting a network channel from among a number of available and acceptable channels. In addition to an initial selection of a network channel when the information transfer is started, the system is able to dynamically adapt to situations where the currently used network channel becomes unavailable or inappropriate and the transfer of information has not yet been completed. Relatedly, the system is able to switch network channels within the course of a particular information transfer or session when it is determined that a more advantageous channel is now available.
The system includes a number of communication units or devices for preparing the information, (e.g., data, a computer program or other software module) for transmission using the selected channel. Such preparation includes making the information compatible with the network that is to carry the information. The compatibility involves establishing the proper network protocol and appending the correct address associated with the network channel over which the information is to be transmitted.
The system further includes a network channel or link selector for automatically and dynamically selecting an appropriate network channel for transmission of information. The link selector communicates with at least one of the communication devices. The link selector conveys the identity of the selected network channel to this communication device so that it can prepare the correct network address that is to receive the information.
With respect to the channel selection process, the link selector obtains information transfer-related requirements for a particular application that is to be performed, e.g., involving the transfer of data. The application performance may involve one or more different uses of the application. These applications requirements are stored in an application requirements database. The application requirements typically include parameters such as bandwidth, destination of information to be transferred, economic factors including cost of transfer and parameters related to the quality of the packet transfer including packet loss, packet latency and packet jitter. The application requirements may also include a security level requirement. The application requirements also include a “weighting vector” for each of the application parameters. The value of the weighting vector might change between or among uses of the particular application. The weighting vector acts as an indicator of the weight to be applied to the particular application parameter, in comparison with the weight that is to be given to the other application parameters. By way of example, a cost requirement may be given ten times the weight of a bandwidth requirement thereby indicating that, for this particular application, the cost of transmission is to be given significantly greater weight in deciding which network channel is to be selected than is the bandwidth parameter.
The link selector also accesses a communications link database that stores network channel parameters. The channel parameters essentially characterize or define the capabilities of the channel. The channel parameters, for each network channel to be analyzed, are checked or analyzed in the context of the particular application requirements, to determine which of the channels are available for possible use. This analysis is typically conducted using dynamically changing channel parameters, as well as static parameters. From the available channels that are found to be acceptable, one or more of them is selected for the particular application. In determining network channels that are deemed acceptable for the current transmission, each of the channel parameters is compared with its corresponding application requirement. If the particular channel parameter cannot satisfy its corresponding application requirement, the network channel under analysis is found to be unacceptable. This acceptability analysis is conducted for each of the available network channels. For each of such channels where one or more particular channel parameters was not able to meet or satisfy the corresponding application requirement, a determination is made that such a channel is not acceptable for the current information transfer. On the other hand, for each network channel that did satisfy all of the application requirements, they have met this stage of evaluation in connection with determining the selected channel. If it occurs that no acceptable channel is available, p
Braitberg Michael F.
Kennedy Patrick J.
Klingenstein Kenneth J.
Spaur Charles W.
Cellport Systems, Inc.
Cong Le Thanh
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