RF Terminal Capability Reporting for Virtual Carrier Allocation
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Solution Overview
Problem
In mobile telecommunication systems, low capability machine type communication (MTC) devices face challenges due to the need for complex receivers to process full bandwidth OFDM carriers, which increases costs and complexity, while direct conversion receivers are prone to interference when the virtual carrier central frequency is not free of data, affecting their efficiency.
Innovation Solution
A terminal with a bandwidth status reporting capability communicates with the base station to allocate unused subcarriers efficiently, allowing virtual carriers to be assigned with central frequencies distinct from the host carrier, reducing interference and enabling simpler receiver architectures for MTC devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MTC devices use conventional full bandwidth OFDM carrier receivers, then communication reliability is maintained, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent segments the full OFDM carrier bandwidth into smaller virtual carrier bandwidths. MTC devices are assigned virtual carriers that occupy only a portion of the total carrier bandwidth, allowing them to use simplified receivers that process only the relevant frequency segments rather than the entire bandwidth, thus reducing receiver complexity while maintaining communication reliability for their data rates
Solution Approach 2:
The patent implements local quality by providing different receiver bandwidth capabilities to different device types. Conventional terminals receive full bandwidth carriers requiring complex receivers, while MTC devices receive virtual carriers with reduced bandwidth requiring simpler receivers. The system adapts the carrier bandwidth locally to match device capabilities, optimizing both complexity and performance
2Device complexity
If direct conversion receivers are used with virtual carriers at non-central frequencies, then receiver simplicity is achieved, but interference from self-mixing increases
Solution Approach 1:
The patent applies preliminary action by having the base station determine and communicate the virtual carrier's central frequency to the terminal before data transmission begins. The terminal then uses this frequency information to properly configure its direct conversion receiver, allowing it to operate at reduced complexity while the base station ensures frequency allocation avoids self-mixing interference conditions
Solution Approach 2:
The base station acts as an intermediary that manages frequency allocation and coordination. It determines appropriate virtual carrier frequencies, communicates these to terminals, and schedules transmissions to avoid creating self-mixing interference conditions, thereby enabling direct conversion receivers to operate reliably
3Productivity
If virtual carriers are allocated without considering terminal bandwidth capability, then allocation speed increases, but interference and operational failures increase
Solution Approach 1:
The patent implements feedback by having terminals report their RF and baseband bandwidth capabilities to the base station during the connection setup process. The base station uses this capability information to make informed virtual carrier allocation decisions, ensuring that each terminal receives a carrier configuration matched to its capabilities, thereby preventing operational failures while maintaining efficient allocation
Data Source
AI summary
Apparatus and method for communicating control data indicative of the capability of RF receiver equipment in wireless telecommunications devices. The control data is then used to allocate transmission resources to the telecommunications devices (including MTC-type terminals). Where a virtual carrier is established to carry data for a given MTC-type device, the position of the center frequency for that virtual carrier is assigned on the basis of both the capability of the RF receiver equipment of that terminal and the degree of traffic congestion on the frequency band at which the virtual carrier has been established.