5G Key Performance Indicators (KPIs) & Optimization

Explore how 5G accessibility KPIs split into non-standalone and standalone categories, including non-standalone KPIs: the secondary G node, B addition success rate, RRC reconfiguration success rate, and Rach success rate.

Explain how a B1 measurement triggers the 4G master node B to add a 5G gNB as a secondary node, followed by RRC reconfiguration and direct data path switching.

Learn how the user equipment measures ss-rsrp and ss-rsrq on neighboring gnb beams using ssb blocks, computes per-beam rsrp, and selects the strongest beam to aid mobility and handover.

Learn how ss-rsrq is calculated from rsrp and rc, guided by the received signal strength indicator, measured over resource blocks with interference and noise to gauge signal quality.

Analyze B1 measurement reports from a user equipment to the master eNodeB, and show how thresholds, offsets, and hysteresis decide time-to-trigger and the addition of a secondary node B.

Optimize B1 events and measurement reports by tuning cell-specific, frequency-specific, and time-to-trigger offsets to balance delay and report validity, while considering blind addition for co-located 4G and 5G nodes.

Measurement gaps let user equipment measure neighboring base stations while the master e node b halts downlink data, reducing the downlink data rate during handover or g node b addition.

Explains how the user equipment measures SSD blocks across beams from a neighboring base station, with SMTC determining measurement gap length and repetition period that repeats groups every 5–160 ms.

Explore 3GPP measurement gap patterns, showing how pattern IDs map to measurement gap length and repetition period in milliseconds, with examples for IDs 0, 1, 6, and 5.

Explore how the measurement gap repetition period affects signaling load and downlink data rate, balancing short or long gaps, and align the measurement window with ssb blocks for B1 detection.

Analyze the 5G NSA accessibility KPI for SgNB addition by examining the standard gNB addition phase, where request and acknowledge counters determine the SgNB addition success rate.

Optimize the secondary gNB addition success rate by tuning dual connectivity preparation timer and CSI report periodicity while managing X2 resources and radio admission control for Qci-based quality of service.

Explain how the RC reconfiguration success rate is calculated in 5G NSA by dividing the RC reconfiguration complete counter by the RC connection counter.

Optimize the RC reconfiguration success rate by tuning the dual connectivity overall timer (outer timer) and the RC supervision timer to balance reduced delay with avoiding RC failures.

Explore the 5G random access procedure (Rach) that establishes uplink synchronization between user equipment and the base station, enabling initial access, handover, rc loss recovery, beam failure recovery, and resynchronization.

Explore the contention based random access procedure in non-standalone 5G, including obtaining RA parameters, sending a preamble on the PRACH, and the random access response window timer.

Describe contention-based random access (cbra)-msg2, where gnb assigns downlink resources for the random access response grant, and the ue uses preamble transmission with power ramping and response windows.

Analyze contention based random access in 5g. Detail CBRA MSG3 and MSG4 flows, preamble ID, temporary C, R and T assignment, uplink/downlink resource grants, and the contention timer.

Contention based random access uses 64 preambles; if two UEs pick the same one, base station scrambles CRC with the first UE's CR and TI, letting that UE win.

Discover how 5G NSA accessibility KPIs assess read success rate through the RACH procedure, with message one and message three counters used to compute uplink synchronization.

Examine why the 5g nsa rach read success rate is treated as a retainability kpi by some vendors, contrasting with its use as an independent kpi in handover.

Contention free random access assigns a preamble via the gNB through an RRC connection reconfiguration, enabling lower latency and more reliable access during handover and secondary gNB addition.

Enable contention free random access where possible and optimize timers, target power, ramping, and B1 threshold/time to trigger to minimize rach delay and interference.

Explore a simplified 5G standalone call flow to understand accessibility KPIs, from system information block one to random access, RRC setup, authentication, and RRC reconfiguration for data transfer.

Define 5G standalone accessibility kpis across random access, rrc setup, and rrc reconfiguration phases. Explain rach sr, rrc connection sr, and rrc reconfiguration sr with optimization parallels to non-standalone.

Explain contention based random access in 5g sa and non-standalone, focusing on temporary crnti assignment by the gnodeb and collision resolution on same preamble.

Understand 5G retainability KPI, the 1 minus call drop rate for voice and data carried over IP, calculated from abnormal and normal releases, with differences between non-standalone and standalone modes.

4g node initiates release of the 5g path, triggers gnodeb release and rrc reconfiguration, switches data to the 4g base station with pdcp sequence transfer and a data usage report.

5G gNodeB initiates the release, 4G base station confirms, 5G base stops data to the user equipment, and the UE completes with the RRC connection reconfiguration complete.

When the UE detects a radio link failure with the 5G gNB, it reports a secondary cell group failure to the 4G master node B, triggering SgNB driven link recovery.

Examine why the user equipment triggers downlink out-of-sync indications, governed by N310, T310, and N311 thresholds, leading to radio link failure.

The lecture describes how a UE triggers radio link failure after reaching the maximum uplink RLC retransmissions (max RTX threshold) with no ack from the secondary G node B.

Explain ue-initiated radio link failures due to secondary cell group reconfiguration or SRB3 integrity failure, detailing signaling on SRB0–SRB2 in the master cell and SRB3 in the secondary link.

Optimize call drops from radio link failures by tuning Raj and E310 timers, increasing N310/N311 and D310, and boosting uplink RLC retransmissions.

Identify how A2 event conditions trigger 5G base station initiated call drops as rsrp/rsrq fall below a threshold with hysteresis, prompting a time-to-trigger and reports to node B before release.

Explain how A2 and B1 thresholds control secondary node B addition and release, prevent ping pong behavior, and recommend setting A2 below B1 to ensure stable operation.

The 5g gnb detects a radio link failure after maximum downlink rlc retransmissions, triggering a call drop announced to the 4g eNodeB.

Explain how consecutive missed downlink CSI reports trigger 5G SgNB radio link failure and call drops, including how CSI loss thresholds and the RLF guard timer determine recovery or drop.

Learn how consecutive missed arq feedbacks from user equipment trigger sgnb initiated call drops, detailing harq operation, arq loss thresholds, radio link failure guard timer, and arq recovery thresholds.

Optimizes call drops due to radio link failures detected by the 5g station by adjusting A2 thresholds, time to trigger, RLC retransmission thresholds, and HARQ and CSI guard timers.

Review 4G master eNB initiated call drops when the 4G path detects a radio link failure. Both the master cell group and the secondary cell group are released, prompting the UE to reestablish with the 4G master eNB and re-add the secondary g node B.

Release 16 adds master cell group fast link recovery using the secondary cell group. Recovery occurs in 30–70 ms via signaling between UE, 5G node B, and 4G master node B.

Explore 5g mobility optimization by examining handover parameter tuning in both non-standalone and standalone deployments, including a three and a five measurement events and vendor-specific implementations.

Explain the a3 event in 5g: trigger when neighboring cell power exceeds serving cell by offsets plus hysteresis, prompting measurement reports and possible handover; cancellation uses offsets minus hysteresis.

An A5 event triggers when the serving cell power falls below threshold minus hysteresis while the neighboring cell exceeds threshold two minus offsets plus hysteresis, prompting potential handover.

Understand the primary secondary cell change handover in NSA 3x, where the UE moves from source to target 5G nodes with measurement reports, 4G involvement, RRC reconfiguration, and path updates.

Explore inter gnb handover in 5g sa, where the source gnb uses UE measurements to trigger admission-controlled handover to the target gnb and switch data path via amf and upf.

Dynamic anchor point selection handover enables seamless transfer from source to target gNB, with the UE receiving downlink from both and uplink sent to one base station to avoid duplicates.

Define Co site neighbors for 4G and 5G from both sides, establish first-tier relationships, and enable inter g node B handover to ensure seamless mobility.

Calculate 5G throughput for uplink and downlink by dividing traffic volume by time, and note how user count in a cell shapes per-user and base station throughput through resource blocks.

Explore how 5g uses modulation schemes to maximize data on a resource element. Compare qpsk, 16qam, 64qam, and 256qam, showing bits per symbol and per resource element.

Adaptive modulation and coding in 5G adjusts to channel conditions. Good channels use higher modulation with weaker coding; bad channels use lower modulation with stronger coding.

Analyze 5G modulation and coding scheme mixes, comparing 64QAM and 256QAM tables, code rate calculations, and spectral efficiency across indices and modulation orders.

Assess whether the 256-QAM feature is enabled in the network and how enabling it maximizes throughput and higher data rates within a given bandwidth.

Discover how carrier aggregation boosts throughput by combining multiple component carriers in 4G and 5G networks, with five LTE and sixteen 5G carriers, subject to vendor and device limits.

Use 5g throughput formula to compute throughput between user equipment and base station, summing component carriers with mimo, bits per symbol, code rate, and overhead, converting to megabits per second.

Compute the downlink theoretical throughput from base station to user equipment using a single component carrier, four MIMO layers, and a 948/1024 code rate, yielding 1150 megabits per second.

Enable split bearer in 5G non-standalone with enhanced dual connectivity to sum data from 4G and 5G paths at 5G secondary node B Pdcp layer, primarily from the 5G path.

Identify and prevent backhaul bottlenecks by understanding the backhaul’s role between core network and radio access network, and by monitoring packet loss and misconfigurations that could limit fronthaul throughput.

Explore 5g nr tdd slot configuration, where mu=3 and a 2.5 ms period yield 20 slots, with seven downlink and four uplink slots, and flexible options via RRC from gnodeB.

Coordinate neighboring gNodeBs to share the same TDD frame structure when using the same frequency, preventing downlink and uplink interference and minimizing out-of-band emissions for adjacent bands.

Describe how SSB block frequency in a beam sweep affects base station data rate, via the five millisecond SSB burst set within a twenty millisecond period and its block counts.

Adjust the SSP burst period and block count to change data rate and cell search time. Lengthen the period or decrease blocks to boost data rate but slow cell search.