MBSFN Subframe Reference Symbol Mapping for Link Adaptation
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Solution Overview
Problem
In communication networks providing Multimedia Broadcast Multicast Service (MBMS), mobile stations face challenges in making measurements of individual base stations for mobility and link adaptation due to the absence of reference symbols for the 3rd and 4th antennas during MBSFN subframes, which limits link adaptation metrics for MIMO streams.
Innovation Solution
The solution involves re-mapping or rotating the association of reference symbols with antenna ports in MBSFN-allocated subframes, allowing observation of all antennas prior to the recommencement of unicast transmissions, and inserting additional reference symbols for antennas 2 and 3 into MBSFN subframes, either by replacing or puncturing multicast symbols, to enable CQI measurements and link adaptation for all antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reference symbols are transmitted only for antennas 0 and 1 during MBSFN subframes, then spectral efficiency is improved, but link adaptation capability for MIMO streams is lost
Solution Approach 1:
The patent applies preliminary action by transmitting reference symbols for all antennas (0, 1, 2, and 3) during the MBSFN subframe before unicast transmission begins. This allows the mobile station to perform channel quality measurements and link adaptation preparations in advance, ensuring that link adaptation capability is maintained without sacrificing spectral efficiency during the actual unicast data transmission.
2Reliability
If reference symbols for antennas 2 and 3 are inserted into MBSFN subframes, then link adaptation for all antennas is enabled, but spectral efficiency is reduced
Solution Approach 1:
The patent applies local quality by selectively inserting reference symbols for antennas 2 and 3 only in specific portions of the MBSFN subframe where they are most needed for link adaptation, rather than transmitting them throughout the entire subframe. This localized approach enables link adaptation capability while minimizing the impact on spectral efficiency during data transmission.
3Measurement precision
If multicast symbols are replaced or punctured to insert reference symbols, then CQI measurements for all antennas become possible, but data transmission capacity is reduced
Solution Approach 1:
The patent applies partial action by replacing or puncturing only the necessary portion of multicast symbols to insert reference symbols for antennas 2 and 3, rather than replacing the entire multicast symbol structure. This partial approach enables CQI measurements for all antennas while minimizing the reduction in data transmission capacity.
Data Source
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AI summary
Various methods and apparatuses provide unicast channel data acquisition, such as antenna information, from Multimedia Broadcast Multicast Service (MBMS) subframes. A method of operating a wireless communications network infrastructure entity is disclosed comprising defining a Multicast Broadcast Single Frequency Network (MBSFN) subframe (400) comprising a unicast symbol (401) in a predetermined first symbol position within said subframe (400), said unicast symbol (401) comprising at least a first unicast antenna reference symbol; defining a second symbol position (403) within said subframe (400) for containing at least a second unicast antenna reference symbol; and transmitting said subframe (400) wherein said unicast symbol (401) comprises said at least first unicast antenna reference symbol and wherein said multicast symbol (403) comprises said at least second unicast antenna reference symbol.