Flex Duplex Handoff Channel Assignment in CDMA Networks
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Solution Overview
Problem
CDMA-to-CDMA handoff times are longer than necessary due to the target base station not being informed of the forward and reverse channel assignments in use prior to handoff, leading to wasted time and a lower success probability, as the current solutions do not address the Flex Duplex capabilities of the mobile station or the channels in use.
Innovation Solution
Incorporating Flex Duplex information into Handoff Required and Handoff Request messages to inform the target base station of the Flex Duplex channels used by the source base station and mobile station, allowing the target base station to prioritize the in-use settings and select compatible channels for handoff, with the option to fall back to fixed-channel configuration if Flex Duplex is not supported.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Flex Duplex capability is implemented with flexible spacing between forward and reverse channels, then spectrum allocation flexibility is improved, but handoff time increases and success probability decreases
Solution Approach 1:
The patent applies preliminary action by having the source base station send Flex Duplex capability information and current channel assignment to the target base station before handoff occurs. This allows the target base station to pre-evaluate compatibility and prepare appropriate channel assignments, eliminating the need for time-consuming capability exchange during handoff and reducing overall handoff time while maintaining spectrum flexibility
2Adaptability or versatility
If Flex Duplex capability information is exchanged during handoff, then target base station can support flexible channel assignment, but handoff procedure complexity increases
Solution Approach 1:
The patent reduces complexity by performing the complex capability evaluation and channel assignment preparation in advance, before handoff. The source base station sends all necessary Flex Duplex information to the target base station upfront, allowing the target to pre-determine compatible channels. During actual handoff, only simple confirmation messages are needed, significantly reducing procedural complexity while maintaining full Flex Duplex functionality
Solution Approach 2:
The patent introduces the A1 and A2 reference interfaces as intermediaries that structure the information exchange between base stations. These standardized interfaces define specific message formats and procedures for transmitting Flex Duplex capability information, current channel assignments, and handoff commands, simplifying the overall interaction complexity through structured communication protocols
3Reliability
If target base station evaluates Flex Duplex capability during handoff, then compatible channels can be selected, but handoff success probability decreases due to rejection delays
Solution Approach 1:
The patent applies preliminary action by having the target base station evaluate Flex Duplex capability compatibility and select appropriate channels before the handoff is executed. The source base station sends the mobile station's Flex Duplex capability information and current channel assignment to the target in advance, allowing the target to pre-determine compatible channels and prepare handoff parameters, thus eliminating evaluation delays during actual handoff and improving both success probability and speed
Data Source
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AI summary
Disclosed is a method for mobile station hard handoff from a source base station (102) to a target base station (100) of a Flex Duplex call in a CDMA wireless communication network that includes a step of establishing (700) Flex Duplex capabilities of the mobile station (104). A next step includes sending (702) the Flex Duplex capabilities of the mobile station (104) to the target base station (100). A next step includes configuring (712) the mobile station (104) and the target base station (100) for the handoff of the call using the Flex Duplex capabilities.