Persistent Systems
Website:
persistent.com
Job details:
About Position:
We are looking for a Telecom Domain Expert to join the team responsible for defining and maintaining the network KPI and analytics layer of our mobile network performance platform. This is a domain-first role: the primary contribution is deep knowledge of mobile network procedures, failure modes, and performance metrics not software development. You will translate that expertise into KPI definitions, formula expressions, protocol error mappings, and dimension data configurations that drive the analytics dashboards and subscriber intelligence features used by mobile operators worldwide. The platform spans the full mobile network stack from 2G CS voice through 3G UMTS, 4G LTE EPC, 5G SA/NSA core, IMS/VoLTE, and roaming interfaces.
- Role: Telecom Domain Expert
- Location: All Persistent Locations
- Experience: 12+ years
- Job Type: Full-Time Employment
What You'll Do:
5G New Radio & 5G Core (Primary Focus)
- In-depth knowledge of 5G core architecture: AMF, SMF, UPF, UDM, AUSF, PCF, NRF, NSSF, CHF, SEPP and their roles in registration, PDU session, and policy procedures
- Deep understanding of NGAP (TS 38.413): UE context management, PDU session resource management, handover (Xn, N2), paging, and NAS transport procedures
- Knowledge of 5G NAS (TS 24.501): 5G-MM (registration, deregistration, service request, mobility update) and 5G-SM (PDU session establishment, modification, release) procedure flows and cause codes
- Understanding of 5G network slicing: NSSAI selection, slice-specific access control (NSAC), per-slice KPI dimensioning, and network slice instance lifecycle
- Familiarity with 5G SA vs NSA deployment architectures (EN-DC, NR-DC): which procedures and interfaces are relevant for each deployment mode
4G LTE & EPC
- Deep knowledge of EMM/ESM (TS 24.301): attach, detach, TAU, service request, bearer management procedures and NAS cause codes
- Working knowledge of S1AP (TS 36.413): E-RAB management, handover (S1, X2), paging, UE context release, and path switch
- Understanding of GTP-C v1/v2 (TS 29.060/29.274): session create/modify/delete, bearer management, and inter-PLMN (S8) roaming sessions
- Understanding of PFCP (TS 29.244): session establishment/modification/deletion between SMF and UPF; FAR, PDR, and URR rule implications for KPIs
- Knowledge of EPC architecture: MME, SGW, PGW, HSS, PCRF roles and their interaction across attach, handover, and charging procedures
2G & 3G Legacy Networks
- Working knowledge of GERAN procedures: location area update, TCH assignment, handover, CS call setup and teardown, BSSAP cause codes
- Working knowledge of UTRAN/UMTS: RANAP procedures, routing area update, inter-RAT handover (SRVCC, IRAT between 3G and 2G/4G), RRC states
- Familiarity with GPRS/UMTS PS domain: PDP context activation, RA update, SGSN/GGSN interactions
- Understanding of Erlang traffic engineering: Erlang B/C, traffic intensity calculation from call duration totals, and its interpretation as a network load KPI
IMS, VoLTE & CS Voice
- Understanding of IMS architecture: P-CSCF, S-CSCF, I-CSCF, HSS/IMS, and their role in VoLTE call establishment
- Knowledge of VoLTE KPIs: call attempt, block, drop, and setup success rate; dedicated bearer establishment for voice; Rx policy authorisation failure modes
- Familiarity with CSFB (Circuit Switched Fallback): SGsAP procedures and the impact on CS call KPI attribution between 4G and 2G/3G
Roaming & Inter-PLMN
- Understanding of roaming procedures across MAP (UpdateLocation, UpdateGprsLocation), Diameter S6a (Update-Location), and GTP-C S8 interface
- Knowledge of MVNO/MNO roaming analytics: distinguishing home vs. visited PLMN procedure attribution; inbound vs. outbound roaming KPI segmentation
- Familiarity with 5G roaming via SEPP (N32): inter-PLMN procedure flows and the KPI implications of vSMF/hSMF and vPCF/hPCF split scenarios
Network KPI Frameworks & Analytics
- Strong understanding of mobile network KPI frameworks: accessibility (registration, session establishment success rates), retainability (drop and block rates), mobility (handover success rates), and integrity (throughput, latency, quality)
- Ability to design composite scoring formulas: weighted combinations of sub-KPIs into operator-level network quality scores and subscriber satisfaction indices
- Familiarity with procedure-level analytics: translating raw protocol event counts into meaningful rate, ratio, and volume metrics interpretable by NOC teams and operators
- Experience reviewing protocol traces or CDRs to validate expected KPI values against analytical output
Configuration & Tooling (No Coding Required)
- Comfort working with JSON and XML configuration files: authoring and editing metric formula definitions, dimension table entries, and validation rule files
- Ability to read and interpret KPI expression trees (arithmetic operations, conditional metric filters by dimension value) and diagnose incorrect formula outcomes
- Basic familiarity with Git for version-controlling configuration changes (mandatory)
- Familiarity with tabular data tools (Excel, SQL, or similar) for reviewing dimension data and spot-checking aggregated KPI values
- Awareness of 6G / IMT-2030 candidate use cases and architecture directions: AI-native networks, integrated sensing and communication (ISAC), non-terrestrial networks (NTN), and the KPI implications for an analytics platform
- Experience with SON (Self-Organising Network) KPIs: MRO, MLB, MRE, and their relationship to handover and interference metrics
- Familiarity with O-RAN architecture and the near-RT/non-RT RIC KPI exposure interfaces
- Knowledge of network slicing SLA assurance KPIs: per-slice throughput, latency, and availability guarantees
- Experience with charging and policy KPIs: online/offline charging event rates, Gy/Gz (4G), Nchf (5G) converged charging procedure success rates
- Familiarity with QoE (Quality of Experience) metrics beyond protocol KPIs: video streaming MOS, gaming latency, and their correlation with network layer
Expertise You'll Bring:
- Define and maintain reporting KPI formulas for mobile network analytics: author JSON-based metric expression trees combining procedure counts, failure counts, durations, and conditional filters by protocol error cause code or procedure type.
- Maintain protocol error cause code mappings: keep congestion, rejection, and failure reason dimensions up to date across 2G (BSSAP), 3G (RANAP/MAP), 4G (S1AP/GTP-C/PFCP/EMM), 5G (NGAP/5G-MM/5G-SM/PFCP), IMS (SIP), and Diameter/MAP interfaces.
- Define and evolve composite network scoring formulas: network accessibility, mobility, retainability, integrity, and subscriber satisfaction scores across CS and PS domains, including weighted combinations of procedure failure rates, handover failure rates, and throughput KPIs.
- Configure and maintain aggregator assignments: mapping KPIs to the correct network layer aggregators (CS core, PS core, CS access, PS access, roaming, subscriber-cell) to ensure metrics are computed at the correct granularity.
- Maintain dimension table content: MCC/MNC operator identity, APN definitions, cell technology classifications (GERAN, UTRAN, EUTRAN, NR), RAT types, bearer types, cause code dictionaries, and protocol interface definitions.
- Configure MDM (Master Data Management) validation rules: XML-based field validation for network element addresses (IP, Point Code, GTT, FQDN), cell technology types, and topology dimension entries.
- Define analytics schedules: configure periodic aggregation jobs for top/bottom subscriber ranking, concurrent call tracking, and subscriber device analytics, including metric selection, grouping dimensions, sort criteria, and publication targets.
- Track 3GPP Release evolution: incorporate new procedure types, cause codes, and interface changes introduced in 5G SA Releases (R16, R17, R18) into KPI definitions and dimension data; monitor IMT-2030/6G standardization for forward-looking metric design.
- Validate KPI output correctness against known network scenarios: review calculated metric values against expected results from protocol traces and collaborate with engineers to correct decoder or aggregation behaviors.
- Work with software engineers building protocol decoders to specify the raw metric primitives procedure attempt counts, success/failure counts, call duration totals, and throughput counters that KPI formulas depend on.
- Define roaming analytics KPIs: location update tracking (Diameter S6a, MAP, GPRS MAP), inter-PLMN procedure success rates, and roaming-specific aggregator configurations.
- Maintain technical documentation covering KPI definitions, formula rationale, and mapping between 3GPP procedure names and platform metric identifiers.
Benefits:
- Competitive salary and benefits package
- Culture focused on talent development with quarterly growth opportunities and company-sponsored higher education and certifications
- Opportunity to work with cutting-edge technologies
- Employee engagement initiatives such as project parties, flexible work hours, and Long Service awards
- Annual health check-ups
- Insurance coverage: group term life, personal accident, and Mediclaim hospitalization for self, spouse, two children, and parents
Values-Driven, People-Centric & Inclusive Work Environment:
Persistent is dedicated to fostering diversity and inclusion in the workplace. We invite applications from all qualified individuals, including those with disabilities, and regardless of gender or gender preference. We welcome diverse candidates from all backgrounds.
- We support hybrid work and flexible hours to fit diverse lifestyles.
- Our office is accessibility-friendly, with ergonomic setups and assistive technologies to support employees with physical disabilities.
- If you are a person with disabilities and have specific requirements, please inform us during the application process or at any time during your employment
Let’s unleash your full potential at Persistent - persistent.com/careers
“Persistent is an Equal Opportunity Employer and prohibits discrimination and harassment of any kind.”
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