PRACH Coverage Enhancements: Receiver Algorithms for Beam Sweeping
Vanhamäki, Ilari (2023)
2023
Sähkötekniikan DI-ohjelma - Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2023-09-14
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202308077476
https://urn.fi/URN:NBN:fi:tuni-202308077476
Tiivistelmä
The deployment of 5G networks brought significant improvements to mobile cellular communications. The main usage scenarios can be categorized into three parts: enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (MTC). However, the realization of new applications and industry developments means that the current 5G will be insufficient in fulfilling the new requirements. 5G Advanced is expected to introduce new technologies as well as continue unfinished items from the previous specification release of 5G. While improving the existing usage scenarios, 5G Advanced is expected to also bring support to three new ones: uplink-centric broadband communication (UCBC), real-time broadband communication (RTBC), and harmonized communication and sensing (HCS).
Network coverage remains to be an important factor regardless of the technology generation. With the introduction of 5G, millimeter-wave frequencies above 30 GHz started gaining more interest and utilization as they provide wider bandwidths for increased data throughput and lower latency. However, the propagation conditions also become more challenging at higher frequencies. Moreover, the limited efficiency and quality of the hardware starts to become more apparent. Therefore, efficient solutions are required to enhance the coverage going forward.
Further coverage enhancement in 5G New Radio (NR) is currently being studied in 3GPP. A conducted study revealed multiple coverage bottlenecks, one of which was the physical random-access channel (PRACH). One of the studied solutions to increase PRACH coverage involves the user equipment (UE) repeating the preamble transmissions by beam sweeping, one repeated transmission per beam.
The objective of this thesis is to study receiver algorithms and beam sweeping performance in PRACH transmissions. This requires implementing algorithms that combine multiple PRACH transmissions to increase the detection performance. Additionally, an algorithm that determines the optimal beam for further transmissions is implemented. The study is carried out by performing link-level simulations with given parameter assumptions.
The results show that the algorithms that utilized all the repetitions in the combining were more effective than those which only chose one repetition based on their selection criteria. It is also observed that even if the UE doesn’t have knowledge of the channel, the detection performance is better with beam sweeping compared to a static wide beam.
Network coverage remains to be an important factor regardless of the technology generation. With the introduction of 5G, millimeter-wave frequencies above 30 GHz started gaining more interest and utilization as they provide wider bandwidths for increased data throughput and lower latency. However, the propagation conditions also become more challenging at higher frequencies. Moreover, the limited efficiency and quality of the hardware starts to become more apparent. Therefore, efficient solutions are required to enhance the coverage going forward.
Further coverage enhancement in 5G New Radio (NR) is currently being studied in 3GPP. A conducted study revealed multiple coverage bottlenecks, one of which was the physical random-access channel (PRACH). One of the studied solutions to increase PRACH coverage involves the user equipment (UE) repeating the preamble transmissions by beam sweeping, one repeated transmission per beam.
The objective of this thesis is to study receiver algorithms and beam sweeping performance in PRACH transmissions. This requires implementing algorithms that combine multiple PRACH transmissions to increase the detection performance. Additionally, an algorithm that determines the optimal beam for further transmissions is implemented. The study is carried out by performing link-level simulations with given parameter assumptions.
The results show that the algorithms that utilized all the repetitions in the combining were more effective than those which only chose one repetition based on their selection criteria. It is also observed that even if the UE doesn’t have knowledge of the channel, the detection performance is better with beam sweeping compared to a static wide beam.