PRACH Resource Sharing Between LTE and NR
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Solution Overview
Problem
Current spectrum sharing configurations between LTE and NR require additional physical resource blocks (PRBs) for random access channel (RACH) processing, leading to inefficient use of uplink shared spectrum.
Innovation Solution
A method where a common set of orthogonal PRACH sequences is assigned to LTE and NR wireless devices in a defined manner, minimizing the number of PRBs reserved for RACH processing by interleaving sequences between the two technologies, allowing for shared use of PRACH resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate RACH processes are implemented for LTE and NR, then each technology can maintain its own random access procedures, but the number of physical resource blocks needed for RACH processing increases
Solution Approach 1:
The patent merges the separate RACH processes of LTE and NR into a unified RACH process that can handle both technologies. A common set of orthogonal Zadoff-Chu sequences is defined that can be used by both LTE and NR devices, allowing the network to detect random access preambles from either technology using the same time-frequency resources, thereby reducing the total number of PRBs required.
Solution Approach 2:
The patent creates universal RACH resources that serve multiple functions - the same PRACH occasions and sequence sets can be used by both LTE and NR devices for random access. This multi-functionality eliminates the need for dedicated separate resources for each technology, resolving the contradiction between maintaining reliable RACH functionality and reducing resource consumption.
2Quantity of substance
If a common set of PRACH sequences is shared between LTE and NR, then the number of PRBs for RACH processing is minimized, but the complexity of sequence assignment and detection increases
Solution Approach 1:
The patent segments the common set of orthogonal sequences into different groups or subsets that can be assigned to different technologies or purposes. By dividing the sequence space systematically, the patent reduces the complexity of managing the common resource pool while still enabling both LTE and NR devices to access appropriate sequences from the shared set.
Solution Approach 2:
The patent utilizes different parameters such as root indices, cyclic shifts, and sequence lengths to differentiate between LTE and NR random access sequences within the common resource pool. By changing these parameters systematically, the patent enables simple identification and processing of sequences belonging to different technologies without requiring complex assignment mechanisms.
3Productivity
If sequences are interleaved between LTE and NR technologies, then spectrum efficiency is improved, but the difficulty of detecting and measuring which device type transmitted increases
Solution Approach 1:
The patent applies the concept of 'color changes' by using distinct sequence characteristics (analogous to colors) that allow the receiver to identify the transmitting device type. Different root indices, cyclic shift patterns, or sequence structures serve as identifiers that enable simple detection of whether an LTE or NR device transmitted, even when sequences are interleaved in the same time-frequency resources.
Data Source
AI summary
A method, system and apparatus for sharing of physical random access channel (PRACH) resources between New Radio (NR) and Long Term Evolution (LTE) radio access technologies (RATs) are disclosed. According to one aspect, a network node is provided. The network node includes processing circuitry configured to: receive a physical random access channel, PRACH, signal from a wireless device; correlate the PRACH signal with one of at least two orthogonal sequences from a common set of sequences shared among a first radio access technology, RAT, and a second RAT; and determine whether the wireless device is operating according to one of the first RAT and the second RAT based at least in part on the correlation.