Control Block Masking with eTFI for GERAN Recipient Filtering
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Solution Overview
Problem
The existing Temporary Flow Identifier (TFI) addressing space in GERAN networks is insufficient, especially with the introduction of Downlink Multicarrier (DLMC) mode, and existing solutions fail to extend the TFI space effectively for FIRE-coded control blocks, leading to compatibility issues between legacy and eTFI-aware mobile stations.
Innovation Solution
A wireless device performs bit-wise modulo two addition between a modified control block and its assigned eTFI and a pre-determined bit pattern to introduce errors, preventing legacy mobiles from decoding the control block, while eTFI-aware devices can correct these errors using FIRE-decoding to verify the intended recipient status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the existing TFI addressing space is used in GERAN networks, then legacy mobile stations can decode control blocks, but the addressing space is insufficient for DLMC mode and cannot support extended TFI (eTFI) devices
Solution Approach 1:
The patent applies preliminary action by pre-defining specific bit positions in the control block where errors will be deliberately introduced. These positions are determined before transmission based on the eTFI value, allowing eTFI-aware devices to later identify and correct these errors while legacy devices cannot decode the blocks. This preparatory error introduction mechanism enables the system to support extended addressing space while maintaining decoding reliability for authorized devices.
Solution Approach 2:
The patent changes the parameter of error distribution in control blocks by deliberately introducing errors at specific bit positions determined by the eTFI value. This transforms the control block from a standard format that all devices can decode into a modified format where only eTFI-aware devices can successfully decode by applying the corresponding error correction. The parameter change in error introduction enables extended TFI support while maintaining backward compatibility through selective decodability.
2Reliability
If errors are deliberately introduced in control blocks to prevent legacy mobiles from decoding, then eTFI-aware devices can verify recipient status, but legacy mobiles may incorrectly decode control blocks
Solution Approach 1:
The patent converts the harmful effect of potential incorrect decoding by legacy devices into a beneficial verification mechanism. By deliberately introducing errors that only eTFI-aware devices can correct, the system transforms what would be harmful decoding attempts by legacy devices into a useful authentication mechanism. Legacy devices that cannot correct the errors will fail to decode, which actually provides reliable verification that the control block is intended only for eTFI-aware devices, preventing unauthorized access or misinterpretation.
3Ease of manufacture
If a pre-determined bit pattern is applied among parity bits to introduce errors, then error introduction is systematic, but the pattern must be distributed over a distance exceeding shortest uncorrectable burst error length
Solution Approach 1:
The patent applies segmentation by dividing the error introduction process into discrete bit positions within the control block. The pre-determined bit pattern is segmented across specific positions, with the constraint that bits must be distributed over a distance exceeding the shortest uncorrectable burst error length. This segmentation approach systematically introduces errors at controlled intervals, making the process manageable and implementable while ensuring that legacy burst error correction mechanisms cannot inadvertently correct these deliberate errors.
Data Source
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AI summary
Methods, a wireless device (110) and a radio network node (120) for managing a control block are disclosed. An extended Temporary Flow Identifier, eTFI, is assigned to the wireless device (110) by the radio network node (120). The radio network node (120) constructs the control information. The radio network node (120) performs a bit-wise modulo two addition with a control block and a combination of the eTFI and a pre-determined bit pattern to obtain a modified control block. The radio network node (120) adds channel coding redundancy. The radio network node (120) maps the modified control block onto physical resources. The radio network node (120) sends the modified control block to the wireless device (110). The wireless device (110) decodes the received modified control block removing the channel coding redundancy, performs a bit-wise modulo two addition between the modified control block and a combination of the eTFI and a pre-determined bit pattern to obtain a control block. The wireless device (110) decodes the control block using FIRE-decoding to obtain the control information. The wireless device (110) determines it is the intended recipient of the control information if the TFI information therein matches its assigned TFI. Corresponding computer programs and carriers therefor are also disclosed.