Pi/2-BPSK Initial Access Signaling for Cell-Edge Uplink Coverage
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Solution Overview
Problem
Existing 5G NR systems do not effectively utilize pi/2-BPSK modulation and coding scheme (MCS) for initial access, leading to suboptimal uplink coverage, especially for cell-edge UEs, due to unclear UE capability and network unawareness of pi/2-BPSK support during the initial access procedure.
Innovation Solution
Implementing network signaling to indicate pi/2-BPSK MCS and DMRS support during the initial access, allowing power boosting and differentiated DMRS sequences to enhance coverage, and using correlation and CRC checks to distinguish between pi/2-BPSK and QPSK transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard BPSK modulation is used for initial access, then the system maintains simplicity and compatibility, but uplink coverage is suboptimal especially for cell-edge UEs
Solution Approach 1:
The patent applies parameter changes by modifying the BPSK modulation scheme to pi/2-BPSK, which changes the phase progression from 0 to pi/2 per symbol. This parameter modification reduces envelope variation and improves power amplifier efficiency, thereby enhancing uplink coverage without significantly increasing device complexity
Solution Approach 2:
The patent introduces dynamic capability indication where UEs signal their pi/2-BPSK support capability during initial access. This dynamic adaptation allows the system to switch between standard BPSK and pi/2-BPSK based on UE capabilities and network configuration, optimizing coverage while managing complexity
2Loss of information
If pi/2-BPSK is implemented without network signaling, then the modulation scheme can be used, but UE capability and network awareness of pi/2-BPSK support remains unclear during initial access
Solution Approach 1:
The patent implements preliminary action by having UEs indicate their pi/2-BPSK capability in the RRC message during initial access before actual data transmission. The network also preliminarily configures and signals pi/2-BPSK support through system information or RRC reconfiguration, ensuring both parties are aware of the capability before utilizing it
Solution Approach 2:
The patent uses RRC messages as an intermediary to convey pi/2-BPSK capability information between UE and network. The RRC connection request and reconfiguration messages serve as the communication medium that establishes mutual awareness of pi/2-BPSK support without requiring additional dedicated signaling protocols
3Reliability
If power boosting is applied for random access, then coverage is improved, but it increases peak power requirements and energy consumption
Solution Approach 1:
The patent applies parameter changes by using pi/2-BPSK modulation which inherently reduces envelope variation compared to standard BPSK. This reduction in envelope variation allows for more efficient power amplifier operation and reduces the need for aggressive power boosting, thereby improving coverage while moderating power consumption increases
Solution Approach 2:
The patent implements feedback mechanisms where the network monitors uplink reception quality and dynamically adjusts power boosting parameters based on actual channel conditions. This feedback-driven approach ensures power boosting is applied only when necessary and at optimal levels, avoiding excessive energy consumption while maintaining coverage
4Reliability
If differentiated DMRS sequences are used for pi/2-BPSK, then collisions are minimized, but the system complexity increases
Solution Approach 1:
The patent applies segmentation by creating separate DMRS sequence spaces for pi/2-BPSK and standard BPSK transmissions. By segmenting the DMRS design into modulation-specific sequences, the system avoids collisions between different modulation types while keeping each segment's processing relatively simple and well-defined
Data Source
AI summary
Methods and apparatus, including computer program products, are provided for pi/2 BPSK initial access. In some example embodiments, there may be provided a method that includes receiving, at a user equipment, information indicating network support of an initial network access based on a pi/2 binary phase shift keying (pi/2-BPSK) modulation and coding scheme; and performing, in response to the received system information, the initial network access by at least sending a connection request based on the pi/2-BPSK modulation and coding scheme. Related systems, methods, and articles of manufacture are also described.