TD-SCDMA Channel Impulse Response Determination
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Solution Overview
Problem
In TD-SCDMA systems, accurately determining channel impulse responses of users in neighboring cells is challenging, leading to increased multiple access interference and reduced system capacity and coverage due to the inability to perform multi-user joint-detection across co-frequency cells.
Innovation Solution
A method is introduced where synchronous ID codes are set and correlated with channel estimation parameters, allowing Node B to detect and compute channel impulse responses of users in neighboring cells by transmitting these codes in uplink pilot slots with the same timing advance as uplink service data, enabling accurate determination of channel impulse responses for multi-user joint-detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multi-user joint-detection is performed only within the same cell, then multiple access interference between users in the cell can be suppressed, but multiple access interference from neighboring cells cannot be eliminated
Solution Approach 1:
The channel estimation method is extended to serve dual purposes: estimating channels for users within the same cell and estimating channels for users in neighboring cells. The base station uses the same midamble correlation technique to obtain channel impulse responses from both intra-cell and inter-cell users, enabling the multi-user joint-detection to process signals from a broader set of users across multiple cells, thereby eliminating inter-cell interference while maintaining the core functionality of channel estimation.
2Adaptability or versatility
If channel impulse response of neighboring cell users is obtained, then multi-user joint-detection can be performed across co-frequency cells, but system complexity increases due to additional interference management requirements
Solution Approach 1:
The method segments users into different groups based on their cell affiliation (intra-cell users and inter-cell users) and applies the channel estimation process separately to each group using the same midamble correlation technique. This segmentation allows the base station to manage channel estimates from multiple cells in an organized manner, reducing the complexity of interference management by treating different user groups systematically rather than handling all users uniformly.
Solution Approach 2:
The base station performs channel estimation for both intra-cell and inter-cell users in advance, before the actual data detection process. By obtaining channel impulse responses from neighboring cell users beforehand using midamble correlation, the system prepares all necessary channel information upfront, which simplifies the subsequent multi-user joint-detection process and reduces real-time computational complexity during data reception.
3Productivity
If accurate channel impulse response determination is achieved for all users, then system capacity and coverage are improved, but measurement precision requirements increase
Solution Approach 1:
Each user transmits their own midamble sequence which contains information about their channel characteristics. The base station uses this self-transmitted midamble from each user to estimate that user's channel impulse response through correlation. This self-service approach allows each user to contribute their own channel information, enabling accurate channel estimation for both intra-cell and inter-cell users without requiring external calibration or additional overhead signals, thereby improving system capacity while maintaining measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enhances the anti-interference ability of the TD-SCDMA system by accurately obtaining channel impulse responses of neighboring users, thereby improving system capacity and coverage by reducing multiple access interference across co-frequency cells.
Implementation Method 1
Node B may obtain information such as scrambling code, code channel and basic midamble used by neighboring cells from configuration information of the system
Data Source
AI summary
The present invention discloses a method for determining user channel impulse response in the TD-SCDMA system, including: setting one or more than one synchronous ID code and establishing corresponding relations between channel estimation parameters of each user and the synchronous ID code and a sub-frame number of a sub-frame transmitting the synchronous ID code; transmitting, by each user, a corresponding synchronous ID code in a sub-frame identified by a sub-frame number corresponding to channel estimation parameters according to the relations established in step A, wherein timing advance of transmitting the synchronous ID code is the same with that of transmitting uplink service data of the user; at Node B, continuing to detect whether there is the synchronous ID code in received signals, if there is one or more than one synchronous ID code, determining the channel estimation parameters of the user transmitting the synchronous ID code according to the detected synchronous ID code, sub-frame number of the current sub-frame and the corresponding relations established in step A; and at Node B, computing the channel impulse response of the user according to the determined channel estimation parameters and arriving time of the detected synchronous ID code.