Carrier Aggregation in Mobile Terminals for Asymmetric Bandwidth
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Solution Overview
Problem
Current mobile communication systems, such as UMTS and LTE, face challenges in supporting multiple coexisting systems due to limitations in handling asymmetric bandwidths between uplink and downlink channels, which restrict the effective use of broadened frequency bands.
Innovation Solution
The mobile terminal apparatus performs a cell search using a synchronization channel signal from one downlink component carrier, and the radio base station broadcasts carrier aggregation information, allowing for the assignment and communication on both downlink and uplink component carriers based on the mobile terminal's transmission/reception bandwidth, enabling initial access procedures for each system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed band of 5 MHz is used in UMTS system, then the system configuration is simple, but the transmission rate is limited to approximately maximum 2 Mbps
Solution Approach 1:
The patent applies dynamics by enabling the mobile terminal and base station to dynamically select and switch between multiple component carriers with different bandwidths (5 MHz for UMTS, 10 MHz for LTE, 20 MHz for LTE-A). This allows the system to adaptively adjust the transmission bandwidth according to channel conditions and service requirements, thereby achieving higher transmission rates while maintaining configuration flexibility through dynamic carrier selection rather than static fixed-band operation.
2Productivity
If variable bands ranging from 1.4 MHz to 20 MHz are used in LTE system, then the transmission rate increases to maximum 300 Mbps, but the system complexity increases to support multiple bandwidth configurations
Solution Approach 1:
The patent implements universality by designing a multi-functional initial access mechanism that can handle multiple bandwidth configurations (1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, 20 MHz) and multiple mobile communication systems (UMTS, LTE, LTE-A) through a unified procedure. The base station broadcasts carrier aggregation information that enables the terminal to perform cell search and random access regardless of the specific bandwidth or system type, thereby achieving high transmission rates across different bandwidths while reducing system complexity through standardized multi-functional access procedures.
3Adaptability or versatility
If multiple mobile communication systems coexist, then the system versatility increases, but the difficulty of detecting and measuring bandwidth information increases
Solution Approach 1:
The patent applies preliminary action by having the base station pre-broadcast carrier aggregation information including bandwidth configuration details before the terminal performs cell search and random access. This advance provision of bandwidth information allows the terminal to properly configure its detection and measurement parameters in advance, thereby enabling accurate bandwidth detection and measurement across multiple coexisting systems (UMTS, LTE, LTE-A) with different bandwidths without increasing the difficulty of the detection process.
4Productivity
If asymmetric bandwidths between uplink and downlink channels are handled traditionally, then the system configuration remains simple, but the effective use of broadened frequency bands is restricted
Solution Approach 1:
The patent explicitly embraces asymmetry by enabling independent bandwidth configuration for uplink and downlink channels through carrier aggregation. The base station can assign different bandwidths to uplink component carriers and downlink component carriers based on traffic demands, allowing the system to effectively utilize broadened frequency bands with asymmetric bandwidth allocation (e.g., 20 MHz downlink with 10 MHz uplink) while managing the increased bandwidth handling complexity through standardized carrier aggregation procedures and broadcast information mechanisms.
Data Source
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AI summary
To provide amobile terminal apparatus and radio base station apparatus supporting each of a plurality of mobile communication systems when the plurality of mobile communication systems coexists, the mobile terminal apparatus performs a cell search using an SCH signal included in one downlink CC among a plurality of downlink CCs, the radio base station apparatus broadcasts a DBCH signal including information of an uplink CC paired with an initial downlink CC including the SCH signal obtained by the cell search, and transmits a response signal of an RACH signal from the mobile terminal apparatus to the mobile terminal apparatus in the initial downlink CC, the mobile terminal apparatus transmits a shared channel signal including information of a transmission/reception bandwidth of the mobile terminal apparatus to the radio base station apparatus in the uplink CC, the radio base station apparatus transmits a control signal including assignment information of a downlink CC and an uplink CC based on the information of the transmission/reception bandwidth of the mobile terminal apparatus to the mobile terminal apparatus, and the radio base station apparatus and the mobile terminal apparatus communicate with each other in the downlink CC and the uplink CC based on the assignment information after random access.