Adaptive Index Mapping for Low Order Modulation
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Solution Overview
Problem
The existing LTE radio technology has limitations in flexibility for selecting modulation schemes, particularly for Machine Type Communication (MTC) devices, which require low power consumption and compatibility with existing LTE devices, due to the 5-bit MCS index limitation and complexity in maintaining multiple modulation schemes.
Innovation Solution
A method is introduced where a node in a cellular network selects a first modulation scheme setting for a device and re-assigns indices to a second modulation scheme setting of lower complexity, such as BPSK or GMSK, adapting the mapping of link parameters to support multiple low complexity modulation schemes efficiently, allowing for flexible configuration of radio links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a new modulation scheme (e.g., BPSK) is introduced to support MTC devices with low power consumption, then power efficiency is improved, but device complexity increases due to the need to maintain compatibility with existing LTE devices
Solution Approach 1:
The patent segments the MCS index space into two distinct sets: a first set of indices for conventional LTE modulation schemes (QPSK and higher) and a second set of indices for low-complexity modulation schemes (BPSK, GMSK). This segmentation allows the system to support multiple modulation types without requiring a complete redesign of the MCS indexing mechanism, thereby reducing the complexity increase while enabling low power consumption modes for MTC devices.
Solution Approach 2:
The patent introduces dynamic configuration mechanisms where the network can adaptively select which modulation scheme set to use based on device capabilities and channel conditions. The UE can be configured with different MCS index mappings dynamically, allowing the system to transition between conventional and low-complexity modulation schemes as needed, thus managing complexity through flexibility rather than requiring all devices to support all schemes simultaneously.
2Adaptability or versatility
If the MCS index table is extended to support additional modulation schemes, then adaptability is improved, but device complexity increases due to maintaining multiple table versions
Solution Approach 1:
The patent makes the MCS index structure universal by defining a single unified table that can map to both conventional LTE modulation schemes and low-complexity modulation schemes. The table includes entries for both QPSK/QAM and BPSK/GMSK, with the network selecting appropriate entries based on the UE's capabilities. This universal table eliminates the need for multiple separate table versions, maintaining adaptability while reducing device complexity.
Solution Approach 2:
The patent changes the parameter mapping within the existing MCS index framework by reusing existing index values (0-31) to represent different modulation schemes depending on the configured mapping type. Instead of extending the table size, the system changes how existing indices are interpreted through parameter reassignment, allowing support for multiple modulation schemes without increasing table complexity.
3Adaptability or versatility
If a complete replacement of the MCS table is implemented to support low complexity modulation schemes, then adaptability is improved, but device complexity increases due to maintaining both old and new tables
Solution Approach 1:
The patent merges the support for conventional LTE modulation schemes and low-complexity modulation schemes into a single unified MCS table structure. The table combines entries for QPSK, 16QAM, 64QAM, and also includes entries for BPSK and GMSK, all within one consistent indexing framework. This merging approach allows the system to support both conventional and low-complexity schemes without maintaining separate tables, thereby improving adaptability while avoiding the complexity of dual table maintenance.
Data Source
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AI summary
A node (100) of a cellular network selects a first modulation scheme setting for a first radio link to a first device (10'). The first modulation scheme setting is selected from a set of modulation scheme settings, each identified by at least one corresponding index. On the basis of a mapping of each of the indices to a corresponding set of transmission parameters, the node (100) identifies a first set of link parameters mapped to the index corresponding to the selected first modulation scheme setting. The node (100) then configures the first radio link according to the identified first set of link parameters. Further, the node (100) selects a second modulation scheme setting for a second radio link to a second device (10). The second modulation scheme setting is based on a modulation scheme of lower complexity than the set of modulation scheme settings. For the second radio link, the node (100) re-assigns one of the indices to the selected second modulation scheme setting and adapts the mapping with respect to the set of link parameters mapped to re-assigned index. On the basis of the adapted mapping, the node (100) identifies a second set of link parameters mapped to the re-assigned index. The node (100) then configures the second radio link according to the identified second set of link parameters. The second modulation scheme setting is associated with Machine Type Communication, MTC, devices, identified by a preamble on a Physical Random Access CHannel, PRACH.