Ericsson RF Engineer Interview Questions and Answers

Interface between LTE refers to the connection between the LTE network and other networks or devices.

• LTE interfaces with other cellular networks such as 3G and 2G through inter-RAT handover

• LTE also interfaces with non-cellular networks such as Wi-Fi and Ethernet through evolved packet core (EPC)

• LTE devices interface with the LTE network through the air interface using radio frequency signals

• LTE also interfaces with cor...read more

X2 interface is a communication interface between two eNodeBs in LTE network.

• X2 interface is used for inter-cell handover and load balancing.

• It is a point-to-point interface that connects two eNodeBs.

• X2 interface is used for exchanging control and user plane data between eNodeBs.

• It is a critical interface for LTE network performance and reliability.

• X2 interface supports various protocols such as S1AP, GTP, and RANAP.

LTE has 20 MHz bandwidth divided into 100 resource blocks. Each resource block has 12 subcarriers and 7 symbols.

• LTE has 20 MHz bandwidth

• Divided into 100 resource blocks

• Each resource block has 12 subcarriers and 7 symbols

KPIs (Key Performance Indicators) of LTE include throughput, latency, coverage, and call setup success rate.

• Throughput measures the amount of data that can be transmitted over the network in a given time period.

• Latency measures the time it takes for data to travel from the source to the destination.

• Coverage measures the area where the network signal is available.

• Call setup success rate measures the percentage of succes...read more

CSFB stands for Circuit Switched Fallback, a technology that allows LTE devices to fallback to 2G or 3G networks for voice calls.

• CSFB is used when a LTE device is unable to make a voice call over the LTE network.

• It allows the device to switch to a 2G or 3G network for voice calls.

• CSFB is a temporary solution until VoLTE (Voice over LTE) becomes more widely available.

• CSFB can cause call setup delays and impact the user

OFDMA is used in LTE to improve spectral efficiency and support multiple users simultaneously.

• OFDMA allows for multiple users to share the same frequency band by dividing it into smaller subcarriers.

• It also enables dynamic allocation of subcarriers to users based on their bandwidth requirements.

• This results in better spectral efficiency and higher data rates.

• OFDMA is also resistant to interference and fading, making it...read more

FDD and TDD are two different duplexing techniques used in wireless communication.

• FDD stands for Frequency Division Duplexing and TDD stands for Time Division Duplexing.

• In FDD, separate frequency bands are used for uplink and downlink communication, while in TDD, the same frequency band is used for both uplink and downlink communication.

• FDD is used in technologies like 2G, 3G, and 4G LTE, while TDD is used in technolog...read more

Massive MIMO stands for Massive Multiple Input Multiple Output. It is a wireless communication technology that uses a large number of antennas at the base station to improve network performance.

• Massive MIMO uses a large number of antennas at the base station to improve network performance.

• It can significantly increase the capacity and coverage of wireless networks.

• It works by using spatial multiplexing to transmit mult...read more

Handover is the process of transferring an ongoing call or data session from one cell to another.

• There are two types of handover: Hard Handover and Soft Handover.

• Hard Handover involves breaking the connection with the current cell before establishing a connection with the new cell.

• Soft Handover involves establishing a connection with the new cell before breaking the connection with the current cell.

• The handover process...read more