OFDM Multi-Carrier Network Entry Procedure
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Solution Overview
Problem
Current wireless communication systems face challenges in achieving high peak transmission rates due to limited transmission spectrum efficiency, requiring wider radio bandwidths and efficient network entry procedures, especially in next-generation OFDM multi-carrier systems.
Innovation Solution
A unified two-stage network entry procedure is introduced for OFDM multi-carrier systems, allowing mobile stations to select a primary carrier for initial network entry and, if supported by both the station and base station, enabling multi-carrier transmission by performing additional ranging on a secondary carrier, with the base station providing a network entry allowance indicator for load balancing and compatibility with both single-carrier and multi-carrier systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single RF carrier is used to carry a wideband radio signal, then the system architecture is simple, but the Peak to Average Power Ratio (PAPR) is high for uplink transmission
Solution Approach 1:
The patent segments the wideband transmission into multiple narrower band RF carriers (e.g., four 10 MHz carriers instead of one 40 MHz carrier). Each carrier uses a smaller FFT size (1024 vs. 4096), which reduces the PAPR for uplink transmission while collectively providing the required wideband capacity
2Loss of energy
If multiple RF carriers are used to carry narrower band radio signals, then the PAPR is reduced and flexibility is improved, but the network entry procedure becomes complex
Solution Approach 1:
The network entry procedure is segmented into two distinct stages: (1) common network entry procedure where the MS selects one carrier as primary and performs initial ranging, and (2) additional network entry procedure where secondary carriers are activated. This segmentation simplifies the overall complexity by breaking down the multi-carrier entry into manageable sequential steps
Solution Approach 2:
The MS performs preliminary actions by selecting a primary carrier and completing full network entry procedures on that carrier before attempting to activate secondary carriers. This preliminary establishment of a reliable primary connection provides a foundation for subsequent multi-carrier operations
3Adaptability or versatility
If a unified network entry procedure is implemented for multi-carrier systems, then flexibility and service capabilities are improved, but compatibility with legacy systems must be maintained
Solution Approach 1:
The network entry procedure is designed to be universal, working for both single-carrier and multi-carrier scenarios. The MS and BS exchange capability information to determine whether to proceed with additional network entry procedures, allowing the same framework to serve both legacy single-carrier devices and advanced multi-carrier devices
4Productivity
If wider radio bandwidths are used to achieve higher peak transmission rates, then the transmission rate is improved, but the transmission spectrum efficiency remains limited
Solution Approach 1:
The patent segments the required 40 MHz bandwidth into multiple 10 MHz carriers, allowing the system to achieve the necessary peak transmission rate (1 Gbps) through aggregated bandwidth while maintaining reasonable spectrum efficiency by using efficient modulation and coding schemes on each individual carrier
Data Source
AI summary
A unified two-stage network entry procedure is provided for OFDM multi- carrier wireless communications systems. During a first stage, a mobile station performs a common network entry procedure using a primary radio frequency carrier and then exchanges multi-carrier capability information with a b ase station. In one embodiment, the base station transmits a network entry allowance indicator to assist the mobile station in selecting the primary carrier. The network entry allowance indicator comprises information of preference of one or more available carriers. During a second stage, the mobile station enables mu lti-carrier transmission over multiple frequency channels if both the mobile station and the base station support multi-carrier capab ility. Before enabling multi-carrier transmission, the mobile station may optionally perform additional ranging by transmitting a ranging request for a secondary carrier. In one embodiment, the base station replies with a ranging response in response to the ranging request through the primary carrier.