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Embedded C Developer - OpenSync/OpenWrt WiFi Router with Cellular Backup
About the Role
We're looking for an Embedded C Developer to work on next-generation residential gateway platforms that combine DOCSIS/fiber WAN connectivity with LTE/5G cellular backup. You'll be developing and maintaining firmware on OpenWrt-based hardware running the OpenSync framework, with direct impact on millions of deployed customer premises equipment (CPE).
Responsibilities
• Design, develop, and debug embedded C software for Linux-based residential gateway platforms (ARM/MIPS SoC)
• Develop and maintain OpenSync managers - event-driven daemons that interact with OVSDB for cloud-managed configuration and state reporting
• Implement and optimize LTE/5G cellular failover and fallback logic including modem management, route arbitration, and WAN healthchecks
• Develop LED state machine logic to provide accurate device status indication across complex multi-WAN scenarios
• Interface with cellular modems via AT commands, QMI/MBIM, USB, and PCIe (MHI) protocols
• Work with WiFi drivers (Qualcomm/Broadcom/Atheros) for 2.4GHz, 5GHz, and 6GHz radio configuration
• Debug kernel-level issues including PCIe enumeration, USB device management, network driver crashes, and kernel panics
• Implement and maintain secure communication channels using TLS with mutual authentication and tunneling protocols
• Analyze and resolve field issues using device logs, crash dumps, and remote diagnostics
• Develop init scripts, UCI configuration handlers, and persistent storage management for OpenWrt
• Write unit tests and participate in code reviews via GitLab merge requests
• Collaborate with hardware teams, QA, cloud platform engineers, and service provider partners
Required Skills
• 5+ years of embedded C development on Linux-based platforms
• Strong proficiency in C programming - pointers, memory management, IPC, event-driven architectures
• Experience with OpenWrt build system, package management, UCI configuration, and JFFS2/SquashFS overlay filesystems
• Familiarity with OpenSync or similar cloud-managed CPE frameworks (OVSDB, protobuf, MQTT telemetry)
• Experience with cellular modem integration - AT commands, QMI, network interface management (rmnet/wwan)
• Strong understanding of Linux networking - routing tables, metrics, netfilter, bridge interfaces, IPv4 and IPv6 dual-stack, neighbor discovery, DHCPv4/DHCPv6, SLAAC, and prefix delegation
• Understanding of TLS handshake with mutual authentication using X.509 certificates, certificate chain validation, and secure provisioning
• Knowledge of security and tunneling protocols - GRE tunneling, IPsec, VPN overlays, and secure encapsulation for cloud-managed traffic
• Experience with event loop frameworks (libev, libuv, or similar)
• Proficiency with debugging tools - GDB, strace, tcpdump, kernel logs, serial console
• Familiarity with Git, GitLab CI/CD, cross-compilation toolchains
• Understanding of WiFi standards (802.11ax/be) and wireless driver configuration
Preferred Skills
• Experience with Qualcomm IPQ series SoCs (IPQ5018, IPQ9574) and NSS/PPE data path
• Experience with Broadcom BCM series chipsets (BCM4908, BCM6750, BCM63178) and Memory Direct Engine (MDE) / hardware acceleration
• Knowledge of Atheros/QCA/BCM wireless chipsets and CFG80211/mac80211 driver architecture
• Knowledge of DOCSIS cable modem interaction and WAN interface management
• Experience with PCIe and USB subsystems in embedded Linux (device enumeration, power management, error recovery)
• Familiarity with eSIM/eUICC provisioning (LPA, GSMA SGP.22)
• Experience with carrier aggregation, NR5G NSA/SA, and multi-band cellular configurations
• Understanding of TR-069/TR-369 (USP) device management protocols
• Basic understanding of TR-181 data model for CPE device management and service configuration
• Experience with Kconfig-based build configuration
• Knowledge of flash storage considerations - wear leveling, persistent partitions, factory reset flows
• Familiarity with thermal management and power management (battery-powered CPE)
Tools & Technologies
• Languages: C, Shell scripting (sh/bash), Python (test automation)
• OS/Platform: OpenWrt (Linux 5.x/6.x kernel), ARM Cortex-A53/A73
• Frameworks: OpenSync, OVSDB, libev, protobuf-c, jansson (JSON)
• Chipsets: Qualcomm IPQ, Broadcom BCM, Atheros/QCA
• Networking: iproute2, iptables/nftables, ovsdb-server, hostapd/wpa_supplicant, GRE, IPsec
• Security: OpenSSL/mbedTLS, X.509 certificates, mTLS, certificate management
• Cellular: Qualcomm QCM/SDX modems, MHI, qcserial, AT+QENG/AT+COPS
• Protocols: IPv4, IPv6, DHCPv4/v6, DNS, MQTT, GRE, TLS 1.2/1.3
• Build: Make, Kconfig, OpenWrt feeds, cross-compilation (musl/glibc)
• Debug: GDB, valgrind, serial console, logpull analysis
• VCS/CI: Git, GitLab, merge request workflows
Nice to Have
• Experience working directly with ISP/MSO/OEM partners
• Exposure to hardware bring-up and board support package (BSP) development
• Experience with Agile/Scrum in a firmware development context
• Familiarity with SCTE/DOCSIS standards
• Understanding of TR-181 data model parameters for WAN management, WiFi configuration, and device monitoring
• Experience with GRE tunnel implementation for backhaul traffic in managed WiFi deployments
What You'll Work On
• Cellular failover/fallback state machines with sub-second transition handling
• LED indication logic for multi-WAN connectivity states
• Modem health monitoring and subsystem restart/recovery
• Internet reachability healthcheck frameworks
• Cloud-managed device configuration and telemetry reporting via MQTT
• Secure cloud connectivity using mTLS with X.509 certificate-based mutual authentication
• GRE tunnel management for cloud-redirected traffic
• Factory reset, firmware upgrade, and persistent storage management
• IPv4/IPv6 dual-stack network configuration, routing, and failover across DOCSIS and LTE interfaces
• WiFi radio configuration and performance optimization across Qualcomm / Broadcom platforms
• Kernel crash analysis and driver-level bug resolution
About Cognizant's IoT Practice:
Intelligent, IoT-enabled products will soon result in the proliferation of data and disrupt virtually all industries. To be successful, both large and small companies must leverage IoT capabilities by designing modern products that fundamentally connect people with processes. Within Cognizant IOT, we engineer industry-aligned, IoT-enabled products that merge industry needs with human drivers. Our intelligent products will revolutionize experiences and result in exciting, transformative outcomes. Without human-centered thinking, connected products are just standalone things-but with it, our modern connected products facilitate a unified way of life enjoyed by all.
*Please note, this role is not able to offer visa transfer or sponsorship now or in the future*

• Applications will be accepted until Aug31 , 2026
• LI#- #LI-SC6

Compensation & Benefits
$104,000- $118,000 per year + Cost of Living Allowance
Bonus + Comprehensive Benefits
Additional Information

• Onsite role
• ⚠️ Visa sponsorship is not available now or in the future. Candidates requiring sponsorship will not be considered.

Benefits: Cognizant offers the following benefits for this position, subject to applicable eligibility requirements:
• Medical/Dental/Vision/Life Insurance
• Paid holidays plus Paid Time Off
• 401(k) plan and contributions
• Long-term/Short-term Disability
• Paid Parental Leave
• Employee Stock Purchase Plan
About Cognizant:
Cognizant (Nasdaq: CTSH) is an AI Builder and technology services provider, bridging the gap between AI investment and enterprise value by building full-stack AI solutions for our clients. Our deep industry, process and engineering expertise enables us to build an organization's unique context into technology systems that amplify human potential, drive tangible outcomes and keep global enterprises ahead in a fast-changing world. See how at cognizant.ai or @cognizant.
Additional employment information
Compensation information is accurate as of the date of this posting. Cognizant reserves the right to modify this information at any time, subject to applicable law.
Applicants may be required to attend interviews in person or by video conference. In addition, candidates may be required to present their current state or government issued ID during each interview.
Cognizant is an equal opportunity employer. Your application and candidacy will not be considered based on race, color, sex, religion, creed, sexual orientation, gender identity, national origin, disability, genetic information, pregnancy, veteran status or any other characteristic protected by federal, state or local laws.
If you have a disability that requires reasonable accommodation to search for a job opening or submit an application, please email [email protected] for roles based in the Americas or [email protected] for roles based in India.