4G LTE/ VoLTE DCR KPI Optimization Nokia Parameter Tuning Now, if this RRC, ReEstablishment also fails and the UE is unable to get a connection, the source eNB will, release the context after expiry of the internal timer. If you are referring to abnormal releases then they are counted under retainability. The eNB1 will consider this a MME induced drop since the eNB1 still holds the UEs context and a release from MME is considered abnormal. Once again, this concept will be covered in a separate topic. IEEE Trans. Some of them can be seen from counters provided by vendors while for others you will need L3 trace analysis. 7 (2008), Nokia buys Eden Rock for self-organizing networks (German). This is the X2 Reloc Overall Timer and the cause of this release will be X2 Reloc Overall Expiry. ; that is if its possible to prevent such UEs from making re attempts in the RAN itself? Can you share the main cause RNL, SRB, SMC, MME? according to your experience, do you recommend to activate ANR on LTE network?since there are some articles on internet suggest activation ANR only on early phases. AOA Ali bhai, As far as my understanding goes it is 200 ms. Can you please suggest what counters to look for or what checks to be done to get to the bottom of it? B = Number of additional E-RABs successful to setup, C = Number of initial E-RABs successful to setup. Just published another article on CSFBhttps://ourtechplanet.com/csfb-circuit-switch-fall-back-explanation-optimization/. Every network is striving to improve this KPI and it has become more important in LTE since the introduction of VoLTE. Such issues were more prevalent around 3 to 4 years ago when ANR functionality was pretty basic. The UE shall select a suitable cell based on idle mode measurements and cell selection criteria. 978-1-4244-2354-5/09/$25.00 2009 IEEE, Hu, H., Zhang, J., Zheng, X., Yang, Y., Wu, P.: Self-configuration and self-optimization for LTE networks. (eds) Futuristic Trends in Network and Communication Technologies. Performance Analysis of KPI's of a 4G Network in a Selected Area of So, the best way to sort this out is to improve radio conditions which is usually done with physical optimization. Hope you are doing well Springer, Singapore. Part of Springer Nature. Hi there However, if you have very high Mo-Signalling percentage then the chances are that RRC Success Rate will be relatively lower compared to another similar network with lower Mo-Signalling percentage. I want to learn more about the KPI optimization process, Please guide and if possible share the Full KPI optimization Link. The most common drop pegged under Radio issues is the drop due to RLC retransmissions. This is a preview of subscription content, access via your institution. To calculate per venue/system, use ( of all RSCs)/# of RSCs. If again ue send rrc connection request then can you tell me how many time ue can send rrc connection request after failure? B = Number of additional E-RABs successful to setup. Can you please post your question under this video on YouTube (URL below) and Ali Khalid will be able to reply then . Xd, tck tfrikt hkll `fmls td ekhdek tck, fje mt rksults mj f cfjedvkr `fmlurk. Perfect. So, the average power per carrier will be reduced leading to a higher probability that the message may not be decoded at the eNB. Again, in this case, if the UE receives a RRC ReEstablishment Rejection from the eNB2, then the UE will initiate a new RRC Connection. So, increasing T302 will increase the interval between such RRC Connection Requests and therefore, reduce the signalling load on the eNB. However, this can increase the signalling load as idle users can try to come back to network more frequently which can increase CPU usage of the eNB. In: International Conference on Wireless Networks, Communications and Mobile Computing (2005), Dttling, M., Viering, I.: Challenges in mobile network operation: towards self-optimizing networks (2009). So, if this timer is small and the UE is trying to send the RRC Connection Setup Complete with retransmissions, then the eNB will consider it a failure as soon as the timer expires. At the eNB level, this can be seen as an abnormal release which is verified from the cause code inside the Context Release message. To calculate average cell availability for plots, compute and display cell availability on the charts/plots (if possible) or the reported Cell unavailability time. thanks. 1. DOCX, PDF, TXT or read online from Scribd, 0% found this document useful, Mark this document as useful, 0% found this document not useful, Mark this document as not useful, One of the most important KPI is the LTE Call Drop Rate. This is the second issue that can happen but it is usually much less observed in commercial networks compared to the failures due to no response. Does it correspond to same UE It will be worth knowing , PDCCH exists in each subframe and each subframe is of 1msec . If, a network has a maximum of 16 RLC retransmissions for downlink, the eNB will send a, message 16 times at the RLC layer and if the UE is unable to decode it or send an, acknowledgement, the eNB will consider this a RLF. So, there is a higher probability of triggering N311 if the value of N310 and T310 is big. What tools can we use? Usually unspecified reason is due to radio issue generally uplink timeouts or N310. 0-7803-7589-0/02/$17.00 2002 IEEE, Khara, S., Saha, S., Mukhopadhyay, A.K., Ghosh, C.K. LTE will be running in parallel with 2G and 3G network. or it named as another names like? For a normal Mo-data or Mt-access, the size of RRC Connection Setup Complete message is around 8 to 10 bytes but for Mo-signalling, it can vary and usually is above 50 bytes. This does not have to be a UE that accesses the network for the first time. if you please tell me the Parameter name in nokia for changing ulMaxRetxThreshold. However, if the UE fails the handover then it tries RRC ReEstablishment after T304 expires and if that also fails then the UE will try a new RRC Connection. User Count Based or Flow Control Based RRC Rejections, Different baseband boards and vendors have different limitations on active user count and CAPS (Call Attempts Per Second). The causes of LTE RRC failures are also covered in detail along with actions that can resolve those issues. This kind of issue can be seen from the traces or CHRs that verifies that it is a single user. So, if it gets a UE Context Release Command from the MME, the eNB will consider this abnormal and it will peg it under MME drop. So, let us get started without wasting any further time. Some vendors wait for a bit longer (an internal timer) for the UE to initiate RRC ReEstablishment and if there is no RRC ReEstablishment then the eNB will release abnormally and radio induced call drop will be pegged. Google Scholar, Li, X.J., Chong, P.H.J. So, increasing this timer might also help in certain scenarios. If it is internal then you can use features like IRC to improve decoding capabilities, CoMP or even SFN can be used to mitigate it. eNBs internal timer is not set to a very small value. (I mean if anything failed after RRC connection setup complete what would happen). : A bandwidth degradation technique to reduce call dropping probability in mobile network systems. Every network is striving to improve this KPI and it has become more important in LTE since the introduction of VoLTE. Hi Ali, Now this, RRC ReEstablishment can be to the serving cell and in that case, it is usually successful since, the serving cell already has the UEs context. The selected PLMN, or: As described before, the HO failure induced drop is pegged under radio due to X2 Reloc Overall Timer expiry. Please follow the link below and post your question/feedback in Youtube comments section so that Ali Khalid will be able to answer. Lets understand with help of different cases that are pegged under MME induced drops. Usually which part will be higher enb or Mme induced drops? The following procedures are usually used based on different scenarios, Conventional Method : Physical Optimization. Abstract and Figures. It is still camped on serving cell at the time of t310 expiry), Or is it the other way around since RLF occured meaning serving cell coverage is weak so most likely neighboring cell has better coverage at that specific location so probably is high of initiating Re-establishment to that neighbouring cell. 2021 CommScope, Inc. All rights reserved. Thanks for good explanations. Consider that UE is static (for simplification) so what actually happens for the same UE if Cell Radius of Target Cell is increased. So, the best way to sort this out is, to improve radio conditions which is usually done with physical optimization. Hi Ali, Good Noon, The size of RRC connection Set Up complete message is too high ( 8 to 100 bytes) when compared to RRC connection Request (7 bytes). Wireless Commun. Multiple Nokia parameters explained which are helpful to improve the DCR KPI like. Some vendors wait for a, bit longer (an internal timer) for the UE to initiate RRC ReEstablishment and if there is no, RRC ReEstablishment then the eNB will release abnormally and radio induced call drop will, The difference between the DL and UL RLC Retransmissions is that in case of DL, retransmissions, the eNB knows that the UE has lost the radio connection, so it can release, the resources and peg a radio induced call drop. Increasing the timer T301 can also reduce RRC ReEstablishment failures but it can also increase the delay from UEs perspective, so it should not be increased excessively. Also, optimization of neighbors and verifying that functional X2 links are present for all the neighbors can greatly reduce the RRC ReEstablishment rejections since most of these rejections are caused due to absence of X2 links. In case of any queries or feedback, please drop a comment below and I would love to respond and help. Telkomnika Indones. - 82.165.198.169. However, this RRC ReEstablishment can also be sent to another cell from eNB2 that does not belong to the source eNB (eNB1). (Pdf) Analysis of A Gsm Network Quality of Service Using Call Drop Rate Would you know how to approach the problem in Ericsson LTE technology? Can 2 different handsets (different vendor) have same FGI? 2019 Springer Nature Singapore Pte Ltd. Mishra, D., Mishra, A. This means that if the network has a higher ratio of RRC Mo-Signalling requests then it will have a lower RRC Success Rate. You should look into the counters for HO failure due to MME, that should show you a more realistic picture. Depends on the UEs coverage at that moment. Can you elaborate more like which functionality are you referring to? When a UE gets a RRC Reject from eNB, it has to wait for T302 seconds before sending another RRC Connection Request. I am trying to keep this vendor independent You should be able to find the timer details in the access related documentation. AAMEEN, *Mubeen Hussain Mohammad* From INDIA(Hyderabad). Hi Ali, In this case, the UE will, wait for a specific time as per T304 and once T304 expires, it will initiate a RRC, ReEstablishment with the cause value of Handover failure. So, in this case, either increase the cell radius of the target cell Secondly, eNB has an internal timer (different vendors have different names for it) which the eNB starts after sending the RRC Connection Setup message. However, this RRC ReEstablishment can also, be sent to another cell from eNB2 that does no, t belong to the source eNB (eNB1). LTE Key Performance Indicator Optimization - IEEE Xplore Hello Mahmoud, KPIs Supported in LTE AP - Ruckus Networks Now, the UE will initiate a new RRC Connection at, on that the eNB2 will forward S1 Initial UE Mess, and it will find out that this UEs context already exists on the eNB1 so it will send a UE, Context Release to the eNB1 and then it will send S1 Initial Context Setup Request to the, eNB2. The MME drops are usually caused by radio issues but they are pegged under MME drops because the eNB has no way of knowing that the drop was caused by a radio issue. FF4FFE9A FGI is observed to be Faulty UE but can it be of any other handset The causes of LTE drops are also covered in detail along with actions that can resolve those issues. Every network is striving to improve this KPI and it has become more important in LTE since the introduction of VoLTE. This message also contains the NAS information if the UE intends to send it. This is usually TMSI but when the UE is not active for a long time or the UE moves to another RAT and then comes back again after some time, the UE sends a random value in the RRC Request. (2019). Increasing the uplink RLC retransmission threshold can help reduce such failures. Out mj hfsk d` [L _LH, fje wmll djly `mje tcms dut wckj tck [K sk, Mjhrkfsmji _LH rktrfjsbmssmdj tcrkscdle td f cmickr vfluk bmict flsd cklp mj rkeuhmji, wmll wfmt `dr f spkhm`mh tmbk fs pkr U875 f, _kKstfolmscbkjt wmtc tck hfusk vfluk d` Cfjedvkr, _kKstfolmscbkjt flsd `fmls fje tck [K ms ujfolk td ik, rklkfsk tck hdjtkxt f`tkr kxpmry d` tck mjtkrjfl, Uck bdst hdbbdj mssuk `dr tcms nmje d` `fmlurk, suhc tcft wckj tck [K mjmtmftks cfjedvkr d, hkll rfemus. The value of UE Inactivity timer also plays an important part, Rate. This will initiate early release for the users and load due to user count will be reduced. https://doi.org/10.1007/978-981-13-3804-5_28, DOI: https://doi.org/10.1007/978-981-13-3804-5_28, eBook Packages: Computer ScienceComputer Science (R0). The eNB pegs RRC attempt counter when it receives the RRC Connection Request and the process is deemed successful on the receipt of the RRC Connection Setup Complete message. Yeah the most common cause is Eutran Generated Reason. What is the particular cause for the LTE call drop with respect to Modem/UE? LTE Call Drop Rate - Our Technology Planet Im trying to figure out how cellular carriers know a call has dropped and how they track it. The session covers the signalling flow for LTE accessibility in detail along with messages where the KPIs are pegged. In simple words, a call drop in LTE means that a user's ongoing session is dropped requiring the user to initiate a new connection to resume services. of all dlTrafficVolume reported for the RSC in a given interval of reporting time. The total power will be distributed in all RB na? T302 should be increased to limit the RRC signalling load. Also, If you liked this article, then please subscribe to our Youtube channel Our Technology Planet for more exciting stuff and videos. This issue is mostly due to coverage and quality problems. HI ALI ; In case of any questions or feedback, please feel free to drop a comment below or connect with him on LinkedIn. The causes of LTE drops are also covered in detail along with actions that can resolve those issues.----------------------------------------------------------------------------------------------------------You can also visit us on our blog site - https://ourtechplanet.com/ in order to read our articles in detail and know more about who we are and what we do.Like Us on Facebook - https://www.facebook.com/ourtechplanet-------------------------------------------------------------------------------------------------------------LTE KPI Optimization (Session 1): ERAB Setup Success Ratehttps://youtu.be/LHAfy45zImgLTE KPI Optimization (Session 2): RRC Success Ratehttps://youtu.be/TbgOBoD7cNQ5G Call Flows \u0026 Signaling: How a 5G UE performs Initial Accesshttps://youtu.be/uLB-WyBpFKE5G Call Flows (Session 2): 5G Intra-gNB \u0026 Inter-gNB Mobility Overviewhttps://youtu.be/VSdc74DS3FABGP Interview Questions and Answers - Learn to Ace a Job Interviewhttps://youtu.be/1fq168DvESw0:00 Start0:32 eNB Initiated Drop: Downlink RLC Issues5:27 eNB Initiated Drop: Handover Issues9:15 MME Initiated Drop: Uplink RLC Issues15:13 MME Initiated Drop: Poor Quality N31020:10 MME Initiated Drop: Handover Drops23:22 Single Bad Problematic UE Issue However, this RRC ReEstablishment can also be sent to another cell from eNB2 that does not belong to the source eNB (eNB1). That is called Single Radio Voice Call Continuity (SRVCC). When we increased T300 from 200ms to 800ms , we observed that RRC SR enhance ( expected ) , but also there was degradation on RA SR , are you ave any clue? Dear Ali , Very good initiative sharing is caring above all it will bless you more with goodness and rewards. In these cases, the eNB rejects the incoming RRC Connection Request by sending a RRC Reject message. But in case of UL RLC retransmissions, the, eNB usually does not know that the UE has reached RLF conditions and will only find this. Hi, If it is external then UL FSS and Interference randomization can help. Nice Explanation A suitable cell is a cell on which the UE may camp on to obtain normal service. 48, 94100 (2010), Moysen, J., Giupponi, L.: From 4G to 5G: self-organized network management meets machine learning. Digital Marketing Institute Well written Ali, thank you for sharing your expertise on this topic. The most common issue for this kind of failure is when the target cell is very far away such that when the UE initiates handover on the target cell, it is at a distance beyond the cell radius. RRC Rejections due to PUCCH congestion can be solved by simply increasing the PUCCH Resource Blocks. However, in uplink, the eNB is usually not aware whether the issue happened on DRB or SRB, so in case of higher drops, both can be changed. Please keep posting for further KPIs too. From the UEs perspective this will be considered a call drop but at the eNB1, the eNB still does not know that this UE has experienced RLF. S1 failures can be caused due to timeout of response message to S1 Initial UE Message. Thanks. Some vendors initiate a UE Context, bit longer (an internal timer) for the UE to initiate RRC ReEstablishment and if there is no, RRC ReEstablishment then the eNB will release a, The difference between the DL and UL RLC Retransmissions is that in case of DL, retransmissions, the eNB knows that the UE has lost the radio connection, so it can release, the resources and peg a radio induced call drop. what is the negative impacts on LTE KPIs in case ANR adding redundant neighboring cells to NRT? Is there any side effects after changing? Consider a UE that experienced RLF due to maximum number of uplink RLC retransmission. Need your suggestion in understanding how Enb can keep exact record of Voice Drops happening at UE analysis of a gsm network quality of service using call drop rate and call setup success rate as performance indicators March 2020 European Journal of Electrical Engineering 1(261):113-121 5G NR | VoLTE | LTE-A | Massive MIMO | NB-IoT | NDO Network Specialist at Ericsson, Australia. To calculate per venue/system, use of all RSCs. Self-optimization in LTE: An Approach to Reduce Call Drops in Mobile Network. Consider a UE that experienced RLF due to maximum number of uplink RLC retransmission. This timer is usually a large value, so such a drop is rare. Nomor Research GmbH, Munich, Germany, 20 May 2008, NGMN Alliance: Next generation mobile networks use cases related to self organising network, overall description, 31 May 2007, Nohrborg, M.: Self-organizing network (2017). I have a question regarding the relation between e-Rab abnormal ReL due to DRB and DRX in Huawei . So, if the N310 value is 2 then it means that if the UE fails to decode PDCCH for 210 ms, it will have exceeded the configured N310 threshold. 43, 704712 (1994), Iraqi, Y., Boutaba, R.: Handoff and call dropping probabilities in wireless cellular networks. LTE KPI Optimization Deep Dive: RRC Success Rate International Conference on Futuristic Trends in Network and Communication Technologies, FTNCT 2018: Futuristic Trends in Network and Communication Technologies LTE KPI Optimization (Session 3): LTE ERAB Drop RateThis video is the third session in LTE KPI Optimization series and explains the LTE ERAB Drop Rate KPI. Keep posting. This issue is mostly due to coverage and quality problems. For instance, enabling Interference Rejection Combining can provide good gains in such scenarios. So, if the UE Inactivity timer is a small value, there will be a greater number of normal releases which can artificially reduce the CDR. UE will keep on sending Service Request to resume Radio connection post detecting RLF and Enb will act on this request by passing SERVICE request to MME and established Bearers. The cell selection criteria are fulfilled. The longterm evolution (LTE) network performance measured by network or drive test key performance indicators (KPIs) can be perfected by parameter tuning. There is 2 of them in Ericsson: DataRadioBearer ulMaxRetxThreshold Xd, mj, tfrikt hkll dr edwjtmlt mt sd tcft mt edks jdt dvkrs, flsd cfppkj mj frkfs wckrk tckrk frk lfrik wftkr odemks fs smijfls kfsmly tkje td ikt, rk`lkhtke dvkr wftkr. To calculate total DL traffic volume per RSC, use the following formula: To calculate total UL traffic volume per RSC, use the following formula: Frequency synchronized is reported as A or calculated in percentage value as. http://cwi.unik.no/images/c/c3/SON_white_paper_NSN.pdf, Dahln, A., Johansson, A., Gunnarsson, F., Moe, J., Rimhagen, T., Kallin, H.: Evaluations of LTE automatic neighbor relations (2011). Excellent articles. Every network is striving to improve this KPI and it has become more important in LTE since the introduction of VoLTE. Very Impressive, Outstanding. Great post. Excellent notes.. Sir.. Really helping me to know about kpi troubleshooting.. Knowl. A = Number of RRC connection establishment successes, B= Number of RRC connection establishment attempts, A = Number of RRC connection re-establishment successes, B= Number of RRC connection re-establishment attempts, A = Number of initial E-RABs successful to setup, B = Number of initial E-RABs attempted to setup, A = Number of additional E-RABs successful to setup, B = Number of additional E-RABs attempted to setup. The details related to troubleshooting and optimizations for such issues is given below. When 4 PUCCH RBs are not enough, they can be expanded to a higher value using parameter or in some implementations, an adaptive approach can be maintained where the eNB changes the PUCCH RB count dynamically based on the load requirement. But in case of UL RLC retransmissions, the, eNB usually does not know that the UE has reached RLF conditions and will only find this. N311 is the In-Sync value and so it is the opposite of N310. This issue is mostly due to coverage and quality problems. So, this reduces the RRC Success Rate of RRC Mo-Signalling compared to other RRC Request types. Very good insight indeed !! Increasing. The value of UE Inactivity timer also plays an important part in the calculation of Call Drop Rate. Required fields are marked *. This is the first part in LTE KPI Optimization and more related articles will be published soon. The session covers the signaling flow for LTE retainability (ERAB Abnormal Release Cases) in detail along with messages where the KPIs are pegged. These messages are big in size and are sent inside the RRC Connection Setup Complete message as NAS. The session covers the signaling flow for LTE retainability (ERAB Abnormal Release Cases) in detail along with messages where the KPIs are pegged. Therefore only T302 can optimize.
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