ETCP 5G RAN Architecture and Deployment 3 — Questions and Answers
Question 1: What is the primary purpose of Ericsson's Radio Dot System?
- Providing outdoor macro coverage at cell edge
- Delivering indoor 4G/5G coverage in large buildings using distributed small radio units (Correct answer)
- Managing fronthaul transport for outdoor radios
- Replacing the RNC in legacy 3G networks
Correct answer: Delivering indoor 4G/5G coverage in large buildings using distributed small radio units
The Ericsson Radio Dot System is an in-building small cell solution where compact radio dot units connect via standard Ethernet to a central baseband unit for indoor coverage.
Question 2: In 5G NR, what does 'SSB (Synchronization Signal Block)' enable a UE to do?
- Perform call setup signaling with the AMF
- Detect the cell, acquire time/frequency synchronization, and decode the master information block (MIB) (Correct answer)
- Establish a data bearer with the UPF
- Perform RF power calibration
Correct answer: Detect the cell, acquire time/frequency synchronization, and decode the master information block (MIB)
The SSB contains the PSS, SSS, and PBCH, allowing a UE to detect a 5G cell, synchronize its timing and frequency, and read basic system information.
Question 3: What is the role of the RRC (Radio Resource Control) protocol in Ericsson's 5G RAN?
- Encrypting the user plane data stream
- Managing UE state (idle/connected/inactive), bearer setup, handover, and system information broadcast (Correct answer)
- Scheduling physical layer resource blocks per TTI
- Compressing IP headers for efficient air interface usage
Correct answer: Managing UE state (idle/connected/inactive), bearer setup, handover, and system information broadcast
RRC runs in the gNB-CU and controls UE state transitions, connection setup, measurement configuration, handover procedures, and system information broadcasting.
Question 4: What does PDCP (Packet Data Convergence Protocol) do in Ericsson's 5G RAN stack?
- Maps logical channels to transport channels
- Performs header compression, ciphering, integrity protection, and in-sequence delivery for data packets (Correct answer)
- Manages HARQ retransmissions on the air interface
- Allocates spectrum resources to users
Correct answer: Performs header compression, ciphering, integrity protection, and in-sequence delivery for data packets
PDCP provides IP header compression (ROHC), encryption, integrity protection, and in-sequence delivery for both control and user plane data in the 5G RAN.
Question 5: In Ericsson's 5G NR, what is the 'UE Inactive state' introduced to improve network efficiency?
- A state where the UE is powered off but retains its IP address
- An intermediate state between Connected and Idle that preserves UE context in the RAN to enable fast re-activation without a full RRC connection setup (Correct answer)
- A state used only during emergency calls
- A low-power state used only for IoT devices in mMTC deployments
Correct answer: An intermediate state between Connected and Idle that preserves UE context in the RAN to enable fast re-activation without a full RRC connection setup
The RRC Inactive state (introduced in 5G NR) stores UE context in the last-serving gNB, enabling the UE to resume data activity with minimal signaling overhead compared to a full re-establishment.
Question 6: What is Ericsson's 'Spectrum Sharing' capability between 4G and 5G called when used on the same physical antenna?
- Multi-band MIMO
- Antenna-Integrated Radio (AIR) with DSS software (Correct answer)
- Carrier Aggregation (CA)
- Licensed Assisted Access (LAA)
Correct answer: Antenna-Integrated Radio (AIR) with DSS software
Ericsson's AIR radios with DSS software support running LTE and 5G NR simultaneously on the same antenna and spectrum, maximizing hardware reuse during 5G rollout.
ETCP 5G RAN Architecture and Deployment 3
What is the primary purpose of Ericsson's Radio Dot System?