Joint Detection for TDD-CDMA Neighboring Cells
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Solution Overview
Problem
In TDD-CDMA systems, multi-user joint-detection is limited to the present cell, as base stations cannot obtain user information, such as midambles and channelization codes, from neighboring cells, leading to incomplete suppression of multiple access interference (MAI) across co-frequency networks.
Innovation Solution
The method involves configuring slot types in neighboring cells, allowing base stations to determine the corresponding relations between midambles and channelization codes, enabling accurate detection and joint-detection of uplink signals from neighboring cells through predefined slot types and high-layer signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-user joint-detection is performed only within the present cell using pre-defined midamble allocation modes, then the implementation complexity is low and the system can operate with existing protocols, but the anti-interference ability is insufficient because MAI from neighboring cells cannot be eliminated
Solution Approach 1:
The network device pre-configures slot types for uplink slots in neighboring cells and notifies base stations of these configurations through high-layer signaling before the actual detection process. This preliminary action provides base stations with the necessary midamble-channelization code correspondence information in advance, enabling them to perform joint-detection on neighboring cell users without requiring complex real-time information exchange or negotiation protocols.
2Ease of operation
If independent midamble allocations are used in each cell to simplify configuration management, then the ease of operation is improved, but the ability to perform uniform multi-user joint-detection across neighboring cells is lost
Solution Approach 1:
The invention introduces a slot type concept that serves multiple functions: it defines the spreading factor, channel estimation window number, and the corresponding relation between midambles and channelization codes. By notifying base stations of neighboring cells' slot type configurations through high-layer signaling, the system enables base stations to universally apply the same joint-detection algorithm across different cells, achieving uniform multi-user joint-detection capability while maintaining independent configuration management in each cell.
3Measurement precision
If base stations obtain only present cell user information to reduce information acquisition overhead, then the loss of time and energy is minimized, but the measurement precision of MAI suppression is insufficient due to missing neighboring cell user information
Solution Approach 1:
The network device acts as an intermediary that collects slot type configuration information for neighboring cells and distributes this information to base stations through high-layer signaling. This intermediary mechanism allows base stations to obtain necessary neighboring cell user information (midamble-channelization code correspondences) without direct communication or complex information exchange protocols between base stations, thereby achieving precise MAI suppression while minimizing information acquisition overhead and time loss.
Data Source
AI summary
A method for performing multi-user joint-detection in a neighboring cell in a TDD-CDMA system presets slot types and includes: a network device configuring a slot type of each uplink slot in its administrated cells and a base station of each cell obtaining a slot type of each uplink slot in a neighboring cell from the network device; the network device configuring for each user a slot for transmitting uplink data and a midamble and channelization code to be used according to the slot type of each uplink slot and a service type of each user in each cell; each user in each cell using the configured midamble and channelization code to transmit uplink data in the configured slot; and the base station detecting activated code channels in the neighboring cell according to the received uplink data transmitted by users in the neighboring cell and obtaining midamble used by each user in the neighboring cell according to the channeliazation codes of the activated code channels and according to the slot type of each uplink slot in the neighboring cell so that the base station may perform the multi-user joint-detection in the neighboring cell.