Reducing PTT Call Setup Delays in CDMA Systems
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Solution Overview
Problem
Push-to-talk (PTT) call setup in CDMA systems experiences significant delays due to the need for establishing packet data connections before sending call control information, resulting in wait times of approximately 10-15 seconds, which is unacceptable for users.
Innovation Solution
Modifications to channel assignment request messaging, such as using IS-2000 Reconnect and Origination Messages, along with common control channel signaling and A9-Short Data Delivery messaging, allow for earlier conveyance of PTT connection request and acceptance information, reducing the end-to-end call setup time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packet data connection is established before sending PTT call control information, then call control information can be conveyed, but call setup time increases to 10-15 seconds
Solution Approach 1:
The patent applies preliminary action by sending PTT call control information during the channel assignment request phase before the packet data connection is fully established. The mobile station includes PTT call control information in the channel assignment request message, allowing the network to prepare the data connection concurrently while the control information is transmitted, thereby reducing call setup time from 10-15 seconds to under 3 seconds while ensuring reliable conveyance of control information.
2Speed
If traffic channel is assigned before data connection establishment, then PTT call can proceed, but call control information transmission is delayed
Solution Approach 1:
The patent merges the transmission of PTT call control information with the channel assignment request process. The mobile station combines PTT call control information with the channel assignment request message, allowing both the traffic channel assignment and control information transmission to occur simultaneously in a single messaging phase, eliminating the sequential delay between these operations.
3Reliability
If session establishment messages are sent after data connection establishment, then data connection is secure, but PTT call setup time increases
Solution Approach 1:
The patent applies preliminary action by transmitting PTT call control information during the channel assignment request phase before the packet data connection is fully established. This allows the network to initiate data connection setup concurrently with control information transmission, reducing call setup time while maintaining connection security through proper authentication and encryption protocols that operate throughout the connection establishment process.
Data Source
AI summary
Various embodiments are described herein to address the need for providing substantially reduced PTT call setup delays. Modifications to channel assignment request messaging (400), such as an IS-2000 Reconnect Message and an IS-2000 Origination Message, are described. In addition, the use of common control channel signaling (e.g., 201), changes to page response messaging (e.g., 301) and new uses for A9-Short Data Delivery messaging (e.g., 203 and 303) are described. Embodiments incorporating some or all of these protocol changes, can provide reduced end-to-end call setup time for PTT as it presently exists in IS-2000 systems.