Sri Chaitanya Techno Schools Preschool Coordinator Interview Questions and Answers

LTE attach procedure is the process of a device connecting to the LTE network and obtaining an IP address.

• The device sends an attach request to the LTE network.

• The network validates the request and assigns a temporary identifier to the device.

• The network sends an attach accept message to the device, which includes the assigned identifier and an IP address.

• The device acknowledges the attach accept message and completes ...read more

CFRA and CBRA are different algorithms used in RACH. Success rates can be fetched separately.

• CFRA stands for Contention Free RACH Algorithm, while CBRA stands for Contention Based RACH Algorithm.

• CFRA is used for devices with higher priority, while CBRA is used for devices with lower priority.

• Success rates for CFRA and CBRA can be fetched separately by analyzing the RACH logs.

• CFRA success rate is usually higher than CBR

We ensure accessibility improvement in LTE network through various measures.

• Conducting regular network audits to identify areas of improvement

• Deploying small cells and repeaters to improve coverage in remote areas

• Implementing carrier aggregation to increase network capacity

• Providing network optimization services to improve network performance

• Collaborating with device manufacturers to ensure compatibility with our netwo...read more

I analyze network data to identify areas with high PS drops and work on optimizing those areas.

• Analyze network data to identify areas with high PS drops

• Optimize network parameters such as RSRP, RSRQ, SINR, etc.

• Check for interference and adjust antenna tilt and azimuth

• Ensure proper handover parameters are set

• Perform drive tests to validate improvements

• Collaborate with other teams such as RF and Core to resolve issues

• Imp...read more

I ensure proper parameter tuning, interference management, and capacity planning for LTE network throughput improvement.

• Regularly monitor network KPIs to identify areas of improvement

• Optimize network parameters such as handover parameters, antenna tilt, etc.

• Implement interference management techniques such as interference coordination, power control, etc.

• Perform capacity planning to ensure sufficient resources are avai...read more

HARQ & TTI Bundling are techniques used in wireless communication to improve data transmission efficiency.

• HARQ stands for Hybrid Automatic Repeat Request and is used to improve the reliability of data transmission by retransmitting erroneous packets.

• TTI Bundling stands for Transmission Time Interval Bundling and is used to reduce latency by transmitting multiple packets in a single transmission time interval.

• The value ...read more

VoLTE e2e call flow is the process of establishing a voice call over LTE network.

• The call is initiated by the user and the device sends a SIP invite message to the IMS network.

• The IMS network authenticates the user and sends a SIP 180 ringing message to the device.

• Once the called party answers, the IMS network sends a SIP 200 OK message to the device.

• The device then sets up the media path and sends a SIP ACK message to...read more

SIP call flow in VoLTE involves signaling between UE, IMS, and PSTN networks.

• UE sends INVITE message to IMS network

• IMS network authenticates and authorizes the user

• IMS network sends INVITE message to PSTN network

• PSTN network sends ringing message to IMS network

• IMS network sends ringing message to UE

• When call is answered, media flow is established between UE and PSTN network

• Call teardown involves exchange of BYE message

The mobile network operator has major involvement in SRVCC.

• SRVCC stands for Single Radio Voice Call Continuity

• It is a feature that allows a seamless handover of voice calls from LTE to 3G or 2G networks

• The mobile network operator is responsible for implementing and supporting SRVCC

VoLTE uses various speech codecs for efficient voice transmission.

• AMR-WB (Adaptive Multi-Rate Wideband) codec is widely used in VoLTE.

• Other codecs used include EVS (Enhanced Voice Services), Opus, and G.711.

• The choice of codec depends on factors such as network capacity, device compatibility, and call quality requirements.

I have worked on LTE & VoLTE features such as QoS, SRVCC, CSFB, TTI bundling, etc. and their related parameters.

• QoS parameters such as ARP, QCI, GBR, MBR, etc.

• SRVCC parameters such as HO margin, HO failure threshold, etc.

• CSFB parameters such as timer values, RAT priority, etc.

• TTI bundling parameters such as bundle size, bundle factor, etc.

• VoLTE parameters such as AMR codec modes, RTP packetization, etc.

• UE categories an...read more

There are 3 MCS (Modulation and Coding Schemes) in LTE.

• MCS 1: QPSK modulation with coding rate of 1/2

• MCS 2: 16QAM modulation with coding rate of 1/2

• MCS 3: 64QAM modulation with coding rate of 2/3

• Higher MCS values indicate higher modulation and coding rates

• The selection of MCS depends on the channel quality and available bandwidth

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

• FDD stands for Frequency Division Duplexing while 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 commonly used in 3G and 4G networks while TDD is commonly used in ...read more

The maximum throughput in LTE network with 20MHz TDD bandwidth depends on various factors.

• Theoretical maximum throughput is 1.6 Gbps

• Practical maximum throughput is around 1 Gbps

• Actual throughput depends on factors like signal strength, interference, number of users, etc.

• Carrier aggregation and MIMO can increase throughput

• Real-world throughput can be measured using tools like speedtest.net