Extended Random Access Subframe Format for LTE Coverage Beyond 100 km
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Solution Overview
Problem
The existing LTE system is unable to support cell coverage beyond 100 km, limiting the range of random access subframes to five predefined formats, which fail to cover distances greater than 100 km effectively.
Innovation Solution
A method for acquiring an extended random access subframe format that adjusts the length of the preamble sequence, Cyclic Prefix (CP), and Guard Time (GT) based on the required cell radius and ZC sequence length, allowing for increased cell coverage by recalculating the number of sampling points and determining the format of the extended subframe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the existing LTE system uses five predefined random access subframe formats, then the system maintains simplicity and compatibility, but the cell coverage radius is limited to 100 km and cannot support over-distance coverage
Solution Approach 1:
The patent changes the parameters of the random access subframe format by extending the preamble sequence length and adjusting the cyclic prefix length. Specifically, it uses a Zadoff-Chu sequence with length 839 and applies a cyclic shift to generate an extended preamble sequence that can support cell radii beyond 100 km, thereby resolving the contradiction between coverage adaptability and format complexity
Solution Approach 2:
The patent introduces dynamic configuration of random access subframe formats by allowing the network to indicate different formats through signaling. The system can dynamically select between extended and non-extended formats based on the required cell coverage, making the format adaptable to different deployment scenarios while maintaining backward compatibility
2Adaptability or versatility
If the cyclic shift length TNcs is increased to support larger cell radius, then the cell coverage radius increases, but the time window for detecting cyclic shifts becomes larger and may cause interference with subsequent subframes
Solution Approach 1:
The patent segments the random access subframe into distinct parts with clear boundaries: extended preamble sequence part, cyclic prefix part, and guard time part. By properly allocating guard time and cyclic prefix lengths, it ensures that the extended cyclic shift window does not interfere with subsequent subframes while still supporting large cell radii
Solution Approach 2:
The patent adjusts multiple parameters simultaneously including the Zadoff-Chu sequence length (839), cyclic shift value, cyclic prefix length, and guard time length. These coordinated parameter changes allow the system to extend cell coverage while maintaining proper timing relationships and avoiding interference with subsequent transmissions
3Adaptability or versatility
If the Guard Time (GT) length is increased to support larger cell radius, then the cell coverage radius increases, but the available time for preamble sequence transmission is reduced
Solution Approach 1:
The patent extends the preamble sequence in the frequency domain by using a longer Zadoff-Chu sequence (length 839) and applying cyclic shifts, rather than simply extending it in the time domain. This dimensional approach allows achieving larger cell coverage through frequency domain spreading while maintaining adequate time duration for transmission
Solution Approach 2:
The patent creates a composite structure for the random access subframe that combines extended preamble sequences with specific cyclic prefix and guard time configurations. This composite design optimizes the distribution of time resources among different components, ensuring both large cell coverage and sufficient preamble transmission time
Data Source
AI summary
A method for acquiring a format of a random access subframe and a receiver are provided. The method includes: according to a cell radius supported currently and a cell coverage radius decided by the length of ZC sequence and the size of Ncs, a receiver determining the length of preamble sequence in an extended random access subframe; according to the cell radius supported currently and a cell coverage radius decided by the length of GT, determining the lengths of CP and GT in the extended random access subframe; according to sampling rates of a system where the receiver is located and the lengths of the preamble sequence and CP and GT, respectively calculating the numbers of sampling points of preamble sequence and GT and CP; based on the above numbers of sampling points, calculating the length of extended random access subframe, and determining the format of extended random access subframe.