Which of the following X2 Interconnection solutions are supported by LTE and NR base stations?
Answer : A, C, D
Interconnection through RF modules (A) is also a supported solution for X2 interconnection between LTE and NR base stations. In this solution, the LTE and NR base stations are connected through RF modules, allowing them to share the same frequency band and resources. This solution is particularly useful for scenarios where there is a need for seamless interworking between LTE and NR networks, such as in the early stages of 5G deployment.
Question 2
In IEEE 1588V2 frequency synchronization, all intermediate transmission devices must support the IEEE 1588V2 protocol.
Answer : A
In IEEE 1588V2 frequency synchronization, all intermediate transmission devices must support the IEEE 1588V2 protocol. This means that all devices that are involved in transmitting the synchronization signal, such as routers and switches, must be able to process and pass on the IEEE 1588V2 messages. If any device in the path of the synchronization signal does not support the IEEE 1588V2 protocol, it will not be able to process and forward the messages, and the overall synchronization will be affected.
Question 3
What is the typical output power of a 64T64R AAU?
Answer : D
According to Huawei's 5G AAU Product Brochure, a 64T64R AAU typically has a maximum output power of 40W. This power is split between the 64 transmitters, so each transmitter has an output power of 0.625W. The output power of an AAU can be adjusted depending on the specific requirements. Sources: [1] Huawei. '5G AAU Product Brochure.' Huawei, 2019. https://www.huawei.com/en/products/5g/aau-product. [2] Wang, X., Ge, X., and Zhang, J. 'Analysis of base station power consumption in 5G ultra-dense networks.' IEEE Access, vol. 7, pp. 85812-85823, 2019. https://ieeexplore.ieee.org/document/8749683.
Question 4
When a GPS divider is used, the maximum distance between the GPS antenna and the BBU is shortened.
Answer : A
When a GPS divider is used, the maximum distance between the GPS antenna and the BBU is shortened. This is because the divider splits the signal from the antenna into multiple signals that can be distributed to multiple BBUs, thus reducing the distance between the antenna and the BBUs. Sources: [1] Rymaruk, O., and Kovalenko, I. 'GPS signal dividers for cellular base stations.' IEEE Antennas and Propagation Magazine, vol. 56, no. 3, pp. 121-126, 2014. https://ieeexplore.ieee.org/document/6833669. [2] Albasri, N., and Al-Naffouri, T.Y. 'GPS signal distribution for a 4G/5G distributed antenna system.' IEEE Access, vol. 7, pp. 100371-100382, 2019. https://ieeexplore.ieee.org/document/8793094.
Question 5
Generally, the gNodeB synchronizes time information from the OSS. Which of the following commands is used to configure the IP address of the time server?
Answer : C
In a gNodeB, the time information is synchronized from the OSS using the Network Time Protocol (NTP). The ADD NTPC command is used to configure the IP address of the NTP server, which is the time server that the gNodeB synchronizes with. This command is used to specify the IP address of the NTP server, the NTP version, and other parameters related to time synchronization.
Question 6
Which of the following statements about a self-contained slot is Incorrect?
Answer : B
Increased GP overhead due to frequent uplink-downlink switching. Self-contained slots are designed to reduce the round-trip time (RTT) by providing faster downlink hybrid automatic repeat request (HARQ) feedback and UL data scheduling, as well as prolonged sounding reference signal (SRS) transmission periods to track fast channel changes and improve MIMO performance. However, they do not involve increased GP overhead due to frequent uplink-downlink switching. High requirements on latency of terminal hardware processing may be involved, depending on the implementation.
The STR CROSFEEDTST command can be used to check for crossed feeder connections of an AAU.
Answer : A
According to Huawei's documentation, the STR CROSFEEDTST command can be used to check for crossed feeder connections of an AAU. It is used to check whether the feeder cables of different antennas are connected to the correct ports. The command can be executed on the AAU to detect crossed feeder connections and ensure that the feeder cables are connected to the correct ports.
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