Code Modification Circuit for Rake Receiver Correlator Integration
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Solution Overview
Problem
Rake receivers in CDMA systems require multiple correlators to handle different transmission paths and pilot signals, leading to increased complexity and silicon footprint due to the need for separate correlators for despread, descramble, and time multiplexed pilot operations.
Innovation Solution
A code modification circuit combines descrambling, de-spreading, and pilot derotation codes into a single correlator using exclusive OR operations, reducing the number of correlators needed by performing these operations simultaneously within a single correlator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate correlators are used for despread, descramble, and time multiplexed pilot operations, then the reliability of signal recovery is improved, but the device complexity and silicon footprint increase
Solution Approach 1:
The patent combines multiple separate correlators (despreading correlator, descrambling correlator, and TMP derotation correlator) into a single integrated correlator. This is achieved by multiplying the received signal by a composite code that contains both spreading and scrambling codes, allowing all three correlation operations to be performed simultaneously in one hardware unit, thereby reducing silicon footprint while maintaining signal recovery reliability
Solution Approach 2:
The integrated correlator is designed to perform multiple functions: despreading, descrambling, and time multiplexed pilot derotation. By making the correlator universal and capable of handling all three operations, the patent eliminates the need for separate dedicated correlators for each function, reducing overall device complexity while preserving the reliability benefits of specialized processing
2Adaptability or versatility
If multiple correlators are provided for each finger in transmit diversity systems, then the adaptability to handle different transmission paths is improved, but the area occupied by the rake receiver increases
Solution Approach 1:
The patent merges the functionality of multiple correlators within each finger into a single integrated correlator structure. By combining despreading, descrambling, and TMP derotation operations into one correlator per finger, the patent maintains the adaptability needed to handle multiple transmission paths while significantly reducing the silicon area required compared to having separate correlators for each operation
3Manufacturing precision
If separate correlators are used for each correlation operation, then the manufacturing precision of signal processing is improved, but the loss of energy increases
Solution Approach 1:
The patent combines multiple correlation operations into a single correlator, reducing the total number of hardware units required. This integration maintains signal processing precision through careful design of the composite correlation process while reducing power consumption by eliminating redundant hardware and reducing the overall computational burden
Data Source
AI summary
The invention provides a code modification circuit for receiving a descrambling/dispreading code at a first input pair thereof and a pilot derotation code at a second input pair thereof, and arranged to combine the codes to form a combined code for providing to a correlator such that the correlator can recover data or a pilot signal from an input sequence supplied thereto.