Packet Data Control Channel Receiver Signal Validation
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Solution Overview
Problem
In mobile communication systems like CDMA2000 1x EV-DV, false alarms and interference occur due to errors in packet data control channels, leading to incorrect Walsh mask updates and reduced transmission efficiency.
Innovation Solution
A receiver apparatus and method that includes a signal level detector and packet data control channel decoder to validate control channel information, preventing false alarms by accurately detecting and decoding control channel signals, and a switch to manage output based on valid slot format indicators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If blind slot format detection is used to determine packet data control channel transmission duration, then the system can operate without explicit slot format indicators, but false alarms occur due to noise misinterpretation leading to incorrect Walsh mask updates
Solution Approach 1:
The patent implements a feedback mechanism where the receiver detects slot format indicators from the packet data control channel and compares them with pre-determined slot formats. The receiver provides feedback by determining whether each detected slot format indicator corresponds to a valid slot format, thereby correcting false alarms from blind detection and ensuring accurate Walsh mask updates only when validation succeeds.
Solution Approach 2:
The patent introduces slot format indicator validation as an intermediary step between blind slot format detection and Walsh mask updates. This intermediary validation mechanism filters out false alarms by verifying whether detected slot format indicators correspond to valid slot formats before allowing Walsh mask updates, thus resolving the contradiction between automatic detection and reliability.
2Productivity
If Walsh mask updates are performed based on received control messages, then packet data channel demodulation can be optimized, but false alarms cause incorrect updates and increased reverse channel interference
Solution Approach 1:
The patent uses feedback validation to determine whether to perform Walsh mask updates. The receiver validates detected slot format indicators against pre-determined valid slot formats and only performs Walsh mask updates when validation succeeds. This feedback mechanism prevents incorrect updates due to false alarms, thereby reducing unnecessary reverse channel interference from false NAK transmissions.
Solution Approach 2:
The patent replaces the direct mechanical link between control message reception and Walsh mask updates with a validation-based control system. Instead of automatically updating Walsh masks upon receiving any control message, the system substitutes a validation mechanism that checks slot format indicator legitimacy, thereby preventing harmful incorrect updates and reducing reverse channel interference.
3Reliability
If continuous monitoring of packet data control channel is performed, then transmission reliability can be improved, but power consumption increases due to constant decoding operations
Solution Approach 1:
The patent applies partial action by performing validation only on detected slot format indicators rather than continuously decoding all packet data control channel messages. The receiver validates slot format indicators against pre-determined valid formats and only performs full decoding and Walsh mask updates when validation succeeds, thereby reducing unnecessary power consumption while maintaining reliability through targeted validation.
Solution Approach 2:
The patent performs preliminary validation of slot format indicators before committing to full decoding operations and Walsh mask updates. By pre-validating detected indicators against a set of valid slot formats, the system avoids unnecessary power-consuming decoding operations when false alarms are detected, thereby reducing power consumption while maintaining reception reliability through preliminary filtering.
Data Source
AI summary
An apparatus and method for receiving a packet data control channel in a mobile communication system that transmits packet data and has the packet data control channel for transmitting control information related to transmission of packet data are provided. A receiver receives and despreads a signal on the packet data channel and a signal on the packet data control channel, separately outputs the signals, and estimates a noise of a received signal. A signal level detector receives a noise estimation value and samples of the packet data control channel signal from the receiver, and outputs a validity signal for detecting whether information is received over the packet data control channel. A packet data control channel decoder decodes the packet data control channel signal if the validity signal received from the signal level detector is valid.