PDSCH Piggybacked DCI for Faster 5G Processing
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Solution Overview
Problem
Existing wireless communication systems face challenges in reducing control overhead and improving processing timelines for downlink control information (DCI) in 5G networks, particularly in scenarios where the DCI is split into two portions, with the second portion being transmitted on the Physical Downlink Shared Channel (PDSCH), leading to potential decoding difficulties due to reduced coding rate and resource element allocation for user data.
Innovation Solution
The method involves splitting the DCI into two portions, where the first portion is transmitted on the PDCCH and the second portion, or 'piggybacked' DCI, is transmitted on the PDSCH, with the TBS determination adjusted to exclude resource elements allocated for the second DCI portion, ensuring efficient decoding by accounting for the piggybacked DCI size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the DCI is split into two portions with the second portion transmitted on the PDSCH, then the control overhead is reduced and processing timeline is improved, but the coding rate is reduced and resource element allocation for user data is reduced
Solution Approach 1:
The DCI is divided into a first portion transmitted on the PDCCH and a second portion transmitted on the PDSCH. This segmentation allows the control information to be distributed across different channels, enabling the UE to process the first portion immediately while the second portion is transmitted alongside user data, thereby improving the processing timeline without significantly impacting the coding rate for user data transmission.
2Device complexity
If the DCI is split into two portions with the second portion transmitted on the PDSCH, then the control overhead is reduced, but the resource element allocation for user data is reduced
Solution Approach 1:
The second portion of the DCI is merged with the user data transmission on the PDSCH. By piggybacking the control information onto the existing PDSCH resources, the system reduces overall control overhead without requiring separate dedicated resources for the second DCI portion, thereby maintaining adequate resource element allocation for user data.
3Measurement precision
If the TBS is determined including resource elements for the second DCI portion, then the transport block size is accurately calculated, but the decoding efficiency is reduced due to the piggybacked DCI size
Solution Approach 1:
The UE determines the size of the second DCI portion beforehand, either through signaling from the gNB or by using predefined parameters. This preliminary knowledge allows the UE to subtract the second DCI portion size from the total PDSCH resources when calculating the TBS for user data, ensuring accurate TBS calculation while maintaining decoding efficiency by avoiding inclusion of control information in the data decoding process.
Data Source
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AI summary
In an aspect, a PDCCH and a PDSCH are transmitted by a BS to a UE, whereby the PDDCH includes a first DCI part and the PDSCH includes a second DCI part. In an example, a TBS associated with the PDSCH may be determined (e.g., either by factoring or ignoring resource elements associated with the second DCI part). In another example, the PDSCH may be associated with a modulation scheme with a constellation having constellation points, whereby the second DCI part in the PDSCH is restricted to a subset of the constellation points. In another example, rate-matching may be performed for one or more resource elements of the second DCI part.