Distributed Carrier Aggregation for Low-Cost MTC Devices
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Solution Overview
Problem
Low-cost MTC devices with a single receiver chain and limited baseband processing capability struggle to implement conventional carrier aggregation techniques on unlicensed bands due to the scarcity of interference-free carriers and complex RF chain design requirements.
Innovation Solution
A distributed carrier aggregation method that tunes an antenna to a first carrier, receives information about a second carrier, and retunes to communicate data, with maximum transmission power based on the second carrier's bandwidth, allowing for operation in unlicensed bands without the need for clear channel assessment or complex RF chain designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional carrier aggregation techniques are implemented on unlicensed bands, then bandwidth extension and data rate improvement are achieved, but device complexity and RF chain design requirements increase significantly
Solution Approach 1:
The patent segments the carrier aggregation function into two parts: control signaling remains on the licensed band while data transmission utilizes unlicensed band carriers. This segmentation allows low-cost MTC devices to achieve carrier aggregation benefits without requiring complex RF chains to simultaneously process multiple carriers, as the device only needs to tune to unlicensed carriers when scheduled for data transmission.
Solution Approach 2:
The patent introduces the licensed band as an intermediary that handles control plane functions (RRC signaling, system information, scheduling assignments). This intermediary approach allows the unlicensed band carriers to be used purely for data transmission, simplifying the RF requirements since devices don't need to simultaneously process control and data on multiple carriers.
2Area of stationary object
If multiple carriers are aggregated for bandwidth extension, then transmission bandwidth increases, but the number of interference-free carriers available on unlicensed bands decreases
Solution Approach 1:
The patent implements dynamic carrier selection where the eNB schedules MTC devices on specific unlicensed carriers based on current interference conditions and device capabilities. Instead of requiring devices to support multiple fixed carriers, the system dynamically assigns carriers through RRC signaling, allowing the same device to adapt to different carrier configurations as unlicensed band conditions change.
Solution Approach 2:
The patent changes the parameter of carrier aggregation from a static hardware configuration to a dynamic software-controlled resource allocation. By using RRC signaling to configure and activate specific secondary carriers based on measured interference levels and network conditions, the system can adapt to the limited availability of interference-free carriers while still achieving bandwidth extension when conditions permit.
3Ease of manufacture
If low-cost MTC devices with single receiver chain are used, then device cost is reduced, but the ability to simultaneously receive multiple carriers is limited
Solution Approach 1:
The patent employs periodic time-division multiplexing where the single receiver chain alternates between receiving control signaling on the licensed band and receiving data on unlicensed band carriers. The eNB schedules transmissions in periodic intervals, allowing the device to sequentially access multiple carriers without requiring simultaneous reception capability, thus maintaining low cost while achieving carrier aggregation benefits over time.
Data Source
AI summary
A method for distributed carrier aggregation on unlicensed bands is described. The method includes tuning an antenna of a user equipment to a first carrier. The method includes transmitting, from an access point on a first carrier, information regarding a second carrier. The method also includes receiving, on the first carrier via the antenna, the information regarding the second carrier. The first carrier and the second carrier are in an unlicensed band. The method includes retuning the antenna to the second carrier and communicating data on the second carrier via the antenna. A maximum transmission power for the second carrier is based at least in part on a bandwidth of the second carrier. Apparatus and computer readable media are also described.