Q1. What is the difference between CFRA and CBRA?
CFRA – Contention FREE Random Access – Preamble reserved Used for Handover between cells and Downlink data transfer requiring UE synchronization
CBRA – Contention BASED Random Access – Preamble randomly selected used for Initial network access, Access following a radio link failure, Handover between cells, Downlink data transfer requiring UE synchronization, Uplink data transfer requiring UE synchronization
Q2. What is Link Adaptation in LTE?
Adjusting transmission parameters according to the channel condition is called link adaptation.
Transmission parameters that can be adjusted are coding rate, modulation scheme, transport block size and tx rank.
Q3. Which transmission scheme is used if two transport blocks are used per TTI and transmission mode 3 is used?
Transmission Mode 3 = Open loop spatial multiplexing
Open loop spatial multiplexing can be TX Diversity or Large Delay CDD.
As question states two transport blocks in one TTI = Two code words in one TTI => Transmission scheme to be used is Large Delay CDD
Q4. Whar are benifits of “Uplink Frequency Selective Scheduling”?
It may improve the peak rate, cell Capacity, covetage and tries to schedule the best part of the frequency band for each UE
Q5. What does the feature “Dynamic GBR Admission Control” mean?
It secures that that there are resources for GBR users and protects non-GBR users from starvation
Q6. What is the difference between connected mode mobility and idle mode mobility?
Idle mode mobility relies on UE measurements and UE decisions whether to make a cell reselection or not. The MME keeps track of the UEs on a TA level.
Connected mode mobility relies on UE measurements and eNB decisions whether to make Handover or not. The UE position is known on cell level by the eNB.
Q7. What is the main task of the UE in handover?
The UE is ordered to make certain measurements and to report events when the event criteria are fulfilled. The eNB evaluates
the measurements and makes HO decisions. In case of an HO, the eNB orders the UE to go to the target cell.
Q8. How many HO events are there in LTE?
A2: Serving cell quality drops below and absolute threshold
A3: A neighboring cell becomes better than serving cell by a certain amount (qHyst).
A5: Serving cell becomes worse than absolute threshold1 AND neighbor cell becomes better than another absolute threshold2.
B2: Serving cell worse than threshold1 AND IRAT neighbor better than threshold2
Q9. Event A2 may trigger in which of following cases?
Blind release with redirect to WCDMA
IRAT HO to WCDMA
IRAT HO to GSM
Blind release with redirect to GSM
Q10. What are the benefits of Redirect with System Information?
CFRA – Contention FREE Random Access – Preamble reserved Used for Handover between cells and Downlink data transfer requiring UE synchronization
CBRA – Contention BASED Random Access – Preamble randomly selected used for Initial network access, Access following a radio link failure, Handover between cells, Downlink data transfer requiring UE synchronization, Uplink data transfer requiring UE synchronization
Q2. What is Link Adaptation in LTE?
Adjusting transmission parameters according to the channel condition is called link adaptation.
Transmission parameters that can be adjusted are coding rate, modulation scheme, transport block size and tx rank.
Q3. Which transmission scheme is used if two transport blocks are used per TTI and transmission mode 3 is used?
Transmission Mode 3 = Open loop spatial multiplexing
Open loop spatial multiplexing can be TX Diversity or Large Delay CDD.
As question states two transport blocks in one TTI = Two code words in one TTI => Transmission scheme to be used is Large Delay CDD
Q4. Whar are benifits of “Uplink Frequency Selective Scheduling”?
It may improve the peak rate, cell Capacity, covetage and tries to schedule the best part of the frequency band for each UE
Q5. What does the feature “Dynamic GBR Admission Control” mean?
It secures that that there are resources for GBR users and protects non-GBR users from starvation
Q6. What is the difference between connected mode mobility and idle mode mobility?
Idle mode mobility relies on UE measurements and UE decisions whether to make a cell reselection or not. The MME keeps track of the UEs on a TA level.
Connected mode mobility relies on UE measurements and eNB decisions whether to make Handover or not. The UE position is known on cell level by the eNB.
Q7. What is the main task of the UE in handover?
The UE is ordered to make certain measurements and to report events when the event criteria are fulfilled. The eNB evaluates
the measurements and makes HO decisions. In case of an HO, the eNB orders the UE to go to the target cell.
Q8. How many HO events are there in LTE?
A2: Serving cell quality drops below and absolute threshold
A3: A neighboring cell becomes better than serving cell by a certain amount (qHyst).
A5: Serving cell becomes worse than absolute threshold1 AND neighbor cell becomes better than another absolute threshold2.
B2: Serving cell worse than threshold1 AND IRAT neighbor better than threshold2
Q9. Event A2 may trigger in which of following cases?
Blind release with redirect to WCDMA
IRAT HO to WCDMA
IRAT HO to GSM
Blind release with redirect to GSM
Q10. What are the benefits of Redirect with System Information?
- The interruption time at release with redirect is shortened as the UE does not have to read system information before accessing the cell.
- It improves the end user experience of the CS Fallback feature and also Inactive UEs can be released quicker.
- System information from target cell is included in the release message
Q11. List ANR functionality in LTE.
- Neighboring cells are added to neighbor lists
- X2 interface is established
- Neghboring cells can be removed from list if they are not used during a predefined time
- OSS-RC is notified about add/remove of neighbor
Q12. Which are the requirements from the UE side in ANR?
- The UE must be capable of reading and reporting CGI. (If a UE capable of reporting CGI is not available, all external cells that
are possible neighbor cells must be defined manually.)
- For inter-frequency ANR and ANR for UTRAN or GERAN it must of course also support the wanted other frequency.
- It must support measurement gaps to measure PCI on other LTE frequencies, scrambling code (SC) of UTRANand Base Station Identity Code (BSIC) of GERAN.
- It must support DRX to be able to measure CGI from neighboring cells.
Q13: Whats is the range of RSRQ in LTE?
UE usually measures RSRP or RSRQ based on the direction (RRC message) from the network and report the value. When it report this value, it does use the real RSRQ value. It sends a non-negative value ranging from 0 to 34 and each of these values are mapped to a specific range of real RSRQ value as shown in the following table from 36.133.
Q13: How many resource elements are used to carry reference signals?
8 RE's are used to carry reference signals and 16 RE's used when 2 antenna ports are in used. To allow the UE to distinguish between the anttena ports reference signals are staggred in time with transmission suspended alternatively on each antenna port when the other is transmitting.