Blind Packet Format Detection in CDMA2000 Control Channels
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Solution Overview
Problem
In CDMA2000 wireless communications systems, mobile stations expend significant processing power and battery life due to the need to test each time slot for three possible packet formats on control channels, leading to increased costs and reduced battery life.
Innovation Solution
A method and system that reduce the number of packet format tests by using a frame counter to determine the correct format based on the number of frames received since the last successful demodulation and adjusting tests according to channel quality, incorporating a demodulator and digital signal processing unit to efficiently decode control channel data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the MS decodes each time slot for all three possible formats (1, 2, or 4 slots), then the MS can reliably detect the correct packet format, but the processing power and computational overhead increase significantly
Solution Approach 1:
The patent applies preliminary action by performing blind detection on the first time slot to determine the packet format before processing subsequent slots. The MS attempts to decode the first slot using all three possible formats (1, 2, or 4 slots) and identifies the correct format through detection algorithms. Once the format is determined in the first slot, this information is used to guide the decoding of remaining slots, eliminating the need to re-test all formats in each subsequent slot.
Solution Approach 2:
The patent segments the packet format detection process into two distinct phases: (1) a first time slot dedicated to blind format detection and testing, and (2) subsequent time slots that use the detected format information for efficient decoding. This segmentation allows the computationally intensive format testing to be performed only once, while subsequent slots benefit from the pre-determined format information, significantly reducing overall processing requirements.
2Reliability
If the MS performs multiple decode operations to test each packet format, then accurate format detection is achieved, but battery power consumption increases and battery life decreases
Solution Approach 1:
The patent performs the energy-intensive format detection operation in advance during the first time slot, establishing the packet format before subsequent data reception and processing. This preliminary action ensures that the correct format is identified upfront, allowing the MS to use this information for efficient decoding of all subsequent slots without repeatedly testing formats, thereby minimizing ongoing power consumption.
Solution Approach 2:
The patent divides power consumption into an initial detection phase (first slot) and a lower-power processing phase (subsequent slots). The first slot consumes more power to perform comprehensive format testing, but this one-time expenditure enables all subsequent slots to be processed with reduced power requirements, as the format is already known and no repeated testing is necessary.
3Reliability
If the MS tests each time slot for all three packet formats, then complete format coverage is ensured, but the time required for detection and processing increases
Solution Approach 1:
The patent performs complete format testing in the first time slot to ensure all possible formats (1, 2, or 4 slots) are evaluated and the correct one is identified. This preliminary comprehensive testing guarantees format detection completeness, and the detected format is then stored and applied to all subsequent slots, eliminating the need for repeated testing and significantly reducing total processing time.
Solution Approach 2:
The patent segments the detection process so that complete format coverage is achieved in the first slot through blind detection, while subsequent slots use this pre-established format information for rapid processing. This segmentation ensures that the thoroughness of complete format testing is maintained while avoiding redundant testing in later slots, thus reducing overall detection and processing time.
Data Source
AI summary
System and method for efficiently detecting packet format from a control channel. A preferred embodiment comprises the use of a slot counter (for example, slot counter 1310) to count the number of slots received (perhaps at a buffer, such as buffer 1305) since the last successfully demodulated packet. Using the slot counter, the number of demodulation attempts can be reduced. For example, if slot counter is one, then a single slot format decode is attempted. If slot counter is two, then a single and dual slot format decode is attempted. Additionally, channel quality can be used to determine likely channel formats. Furthermore, when multiple control channels are used, decoding information regarding one control channel can assist in determining the slot format of another.