MPDCCH for Bandwidth-Limited MTC UE Random Access
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Solution Overview
Problem
Bandwidth-limited MTC UE faces challenges in receiving all PDCCH control information and decoding random access responses, affecting the success of random access in the LTE system, with no effective solutions currently available.
Innovation Solution
The eNodeB configures and sends PRACH resources to MTC UE through a PDSCH indicated by an enhanced or physical downlink control channel, allowing for dedicated or shared PRACH resources, and sends downlink control information and random access responses to facilitate successful random access, using ePDCCH or PDCCH based on system bandwidth and UE capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If MTC UE uses reduced bandwidth (1.4-5 MHz) to reduce cost, then device cost is reduced, but the UE cannot receive all PDCCH control information sent by large-bandwidth system
Solution Approach 1:
The patent segments the downlink control information transmission by introducing a new control channel (MPDCCH) specifically for MTC UEs, separate from the conventional PDCCH. This allows MTC UEs with limited bandwidth to receive control information through a dedicated channel that operates within their reduced bandwidth capabilities, while conventional UEs continue to use PDCCH without interference.
Solution Approach 2:
The patent introduces MPDCCH as an intermediary control channel that mediates between the system's need to transmit control information and the MTC UE's bandwidth limitations. The MPDCCH acts as a specialized intermediary that carries random access responses and other control information in a bandwidth-efficient manner suitable for low-cost MTC devices.
2Ease of manufacture
If MTC UE uses reduced bandwidth, then device cost is reduced, but random access response decoding becomes difficult
Solution Approach 1:
The patent applies local quality by configuring the MPDCCH with specific properties optimized for MTC UE reception. The control channel is placed in specific frequency locations (e.g., centered in the MTC UE's bandwidth) and uses specific resource allocations that match the local bandwidth capabilities of MTC UEs, making decoding feasible within their limited bandwidth while conventional UEs are unaffected.
Solution Approach 2:
The patent changes key parameters of the control channel transmission, including using different resource block allocations, different scrambling codes, and different time-frequency structures for MPDCCH compared to conventional PDCCH. These parameter changes enable MTC UEs to decode random access responses within their reduced bandwidth while maintaining compatibility with the overall LTE system.
3Ease of manufacture
If MTC UE uses reduced bandwidth, then device cost is reduced, but random access success rate is affected
Solution Approach 1:
The patent achieves universality by designing the MPDCCH to serve dual purposes: it provides dedicated control information transmission for MTC UEs with reduced bandwidth while maintaining compatibility with the overall LTE random access procedure. The same physical random access channel (PRACH) resources are used by both MTC and conventional UEs, but the control responses are differentiated through the introduction of MPDCCH, ensuring both UE types can successfully complete random access.
Data Source
AI summary
The information processing method includes: an evolved NodeB sending information of PRACH resources configured for a UE to the UE via a PDSCH indicated by a downlink control channel, and after receiving a random access preamble sequence sent from the UE, the evolved NodeB sending downlink control information and a Random Access Response (RAR), wherein the downlink control channel is an enhanced Physical Downlink Control Channel (ePDCCH); or, information carried by PBCH indicates that the downlink control channel is the ePDCCH or a physical downlink control channel; or, when the LTE system bandwidth is less than or equal to the reception bandwidth of the UE, the downlink control channel is a physical downlink control channel, and when the LTE system bandwidth is larger than the reception bandwidth of the UE, the downlink control channel is the ePDCCH.