Inter-RAT Carrier Aggregation Signaling for Uplink Data Rate Optimization
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Solution Overview
Problem
In wireless communication systems, particularly in HSPA uplink, data-to-control interference limits high data rates due to the need to maintain low rise-over-thermal levels, making it difficult to achieve high uplink data rates.
Innovation Solution
Implementing inter-RAT aggregation by using an HSPA carrier as the primary carrier and an LTE carrier as the secondary carrier, along with a signaling mechanism to inform the Radio Network Controller of the radio access technology associated with data packets, allowing for separate management of physical layer procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HSPA carriers are used for dual-carrier operation with primary carrier carrying control channels, then uplink data rates can be increased, but control channel performance deteriorates due to data-to-control interference
Solution Approach 1:
The system segments control channels and data channels onto separate carriers. Control channels are confined to the primary HSPA carrier while data channels can utilize both primary and supplementary carriers, thereby isolating control channel performance from data-to-control interference and enabling higher uplink data rates on the data carriers.
Solution Approach 2:
The patent introduces an intermediary signaling mechanism (control message with RAT indication) that mediates between the base station and network controller. This signaling allows the network controller to identify whether data packets were transmitted over HSPA or LTE carriers, enabling appropriate processing and power control adjustments for each RAT type.
2Productivity
If inter-RAT aggregation with LTE secondary carrier is implemented, then data-to-control interference is reduced, but system complexity increases due to multiple radio access technologies
Solution Approach 1:
The base station is designed with multi-functionality to support both HSPA and LTE radio access technologies. The same base station infrastructure can simultaneously serve as an HSPA NodeB and an LTE eNodeB, aggregating carriers from both RATs and forwarding data to the network controller through a unified interface.
3Productivity
If control channels are completely removed from supplementary carrier, then RoT levels can be increased for higher data rates, but control functionality is compromised
Solution Approach 1:
The patent extracts control channels from the supplementary carrier, confining them exclusively to the primary carrier. This extraction allows the supplementary carrier to operate at higher RoT levels dedicated to data transmission, while control channel reliability is preserved on the primary carrier where they remain isolated from data-to-control interference.
Data Source
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AI summary
A signaling mechanism informs a Radio Network Controller (700) of the radio access technology associated with data packets forwarded to the Radio Network Controller (700) from base stations (600) supporting multiple radio access technologies. With this information, the Radio Network Controller (700) can associate received data with the corresponding radio access technologies, and thus manage differing physical layer procedures, such as outer-loop power control, for the radio access technologies. In an example method, first and second data units transmitted by a mobile station over first and second radio access technologies, respectively, are forwarded (430) from one or more base stations to a network control node for further processing. A control message associated with at least some of the data units is also sent (440) to the network control node, the control message indicating the radio access technology over which the associated data units were transmitted.