Reference Signal Transmission in LTE-A Resource Blocks
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Solution Overview
Problem
In wireless communication systems, particularly in LTE-A, the transmission of reference signals for additional antenna ports interferes with the detection performance of the Physical Broadcast Channel (PBCH) and Primary/Secondary Synchronization Signal (P/S-SS), leading to power imbalance and performance degradation, especially when trying to maintain backward compatibility with LTE UEs.
Innovation Solution
The method involves transmitting reference signals for additional antenna ports in disjoint sets of resource blocks, excluding those used for PBCH and P/S-SS, and using virtual antenna mapping to distribute transmission power evenly across all antenna ports, ensuring that PBCH and P/S-SS are not punctured, and maintaining the same transmission structure for LTE UEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference signals for additional antenna ports are transmitted in resource blocks used for PBCH and P/S-SS, then channel measurement capability for LTE-A UEs is improved, but detection performance of PBCH and P/S-SS deteriorates
Solution Approach 1:
The resource blocks are segmented into two disjoint sets: one set for transmitting reference signals of additional antenna ports and another set for transmitting PBCH and P/S-SS. This segmentation prevents interference between reference signals and broadcast/synchronization signals, ensuring both channel measurement capability and detection performance are maintained.
Solution Approach 2:
The resource allocation is extended into the frequency domain by creating disjoint sets of resource blocks. Instead of competing for the same time-frequency resources, reference signals and broadcast/synchronization signals are allocated to different frequency resources, eliminating interference while maintaining both functions.
2Power
If transmission power is concentrated on fewer antenna ports, then signal strength for those ports is improved, but power balance across antenna ports deteriorates
Solution Approach 1:
Different resource block allocations are provided to different antenna ports based on their specific requirements. Antenna ports with better channel conditions receive reference signals in resource blocks that do not conflict with PBCH/P/S-SS, while maintaining appropriate power distribution across all antenna ports through virtual antenna mapping.
Solution Approach 2:
Virtual antenna mapping dynamically adjusts the mapping between physical antenna ports and logical antenna ports based on channel conditions. This allows the system to change the effective transmission parameters to maintain power balance while optimizing signal strength for each antenna port.
3Measurement precision
If LTE-A systems use eight antenna ports with full resource block allocation, then channel measurement accuracy is improved, but backward compatibility with LTE UEs deteriorates
Solution Approach 1:
The resource blocks are segmented into disjoint sets, allowing LTE-A UEs to utilize reference signals from additional antenna ports in resource blocks not used by PBCH/P/S-SS, while LTE UEs continue to operate using the traditional four antenna ports without being affected by the additional reference signal transmissions.
Solution Approach 2:
The disjoint resource block allocation structure serves multiple functions: it enables LTE-A UEs to access reference signals for eight antenna ports while simultaneously ensuring that LTE UEs can continue to operate with four antenna ports without interference, achieving universal compatibility across different UE types.
Data Source
AI summary
A method and apparatus for transmitting reference signals in a wireless communication system is disclosed. The method and apparatus includes reference signal, RS, transmission in resource blocks supporting multiple antenna port transmission, at least one broadcast channel being provided in resource blocks belonging to a first set of resource blocks, a first number of reference signals being transmitted in at least one resource block supporting multiple antenna port transmission and a second number of reference signals being transmitted in at least one resource block belonging to a second set of resource blocks. Preferably, different resource elements, REs, are used for each reference signal in resource blocks. An example embodiment of reference signal support of, e.g., eight antenna ports is provided.