TDD Uplink Channel Transmission via Antenna Switching
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Solution Overview
Problem
In TDD systems, user equipment (UE) with multiple antennas can only transmit data over a single antenna, limiting the system's ability to achieve multi-antenna performance and preventing Node B from acquiring a full uplink channel matrix during UE uplink transmission.
Innovation Solution
The UE alternates uplink channel transmission over multiple antennas in the time domain, and Node B determines the used antenna based on downlink control channel information to ensure consistent channel estimation and acquire a full channel matrix, enabling multi-antenna performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If UE transmits uplink channel over a single antenna, then hardware complexity is reduced, but multi-antenna performance and transmission diversity are lost
Solution Approach 1:
The patent applies periodic action by having the UE transmit uplink channels alternately over different antennas in different TTIs. The transmission antenna is switched periodically based on a predetermined rule (e.g., even TTI uses antenna 1, odd TTI uses antenna 2), enabling transmission diversity without requiring concurrent multi-antenna transmission capability. This resolves the contradiction by achieving multi-antenna performance through time-domain switching rather than spatial-domain simultaneous transmission.
2Reliability
If UE alternates transmission over multiple antennas in time domain, then transmission diversity is achieved, but Node B cannot acquire full channel matrix for each TTI
Solution Approach 1:
The patent applies preliminary action by having Node B store the channel matrix information acquired from previous TTIs. When the UE transmits on a specific antenna in the current TTI, Node B combines this current channel information with the previously stored information to reconstruct the full channel matrix. This preliminary storage and combination approach ensures that Node B always has access to complete channel state information for MIMO operations, resolving the information loss issue.
Solution Approach 2:
The patent applies feedback by implementing a mechanism where Node B determines which antenna the UE is using based on downlink control channel information, and uses this feedback to selectively combine channel estimates from different TTIs. The system feedback loop ensures that Node B can accurately reconstruct the full channel matrix by knowing which antenna transmitted in each TTI, thereby maintaining complete channel information despite time-domain switching.
3Device complexity
If UE is scheduled with single uplink timeslot per TTI, then resource allocation is simplified, but antenna switching capability is restricted
Solution Approach 1:
The patent applies dynamics by implementing flexible antenna switching rules that adapt to different scheduling scenarios. The UE determines the transmission antenna based on dynamic factors including TTI index, downlink control channel information, and predetermined rules. This dynamic antenna selection mechanism allows the system to maintain simple resource allocation (single uplink timeslot per TTI) while still achieving versatile antenna switching capability through time-domain multiplexing and adaptive antenna selection.
Data Source
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AI summary
The invention discloses a method and user equipment (UE) for uplink channel transmitting in the time division duplex (TDD) system, wherein the method includes: after entering the multiple input multiple output (MIMO) mode, the UE obtains the resources assigned by the network side; if the resource is a single uplink time slot in a transmission time interval (TTI), the multiple antennas in the UE carry out the uplink channel transmission in turn among the TTIs alternately; if the resources are multiple uplink time slots in a TTI, the multiple antennas in the UE carry out the uplink channel transmission in turn among the uplink time slots alternately. The invention also discloses a method and base station for channel estimating in the TDD system. By the invention, the bit error capability of the data can be improved in the case that the UE in the TDD system has multiple antennas, the whole uplink channel estimation can be obtained, and the multiple antennas capability of the TDD system can be ensured.