Ericsson Placement Papers 2026 — Complete Preparation Guide

Last Updated: March 2026

Meta Description: Prepare for Ericsson 2026 campus placements with our comprehensive guide featuring the hiring process, 20+ solved technical questions on 5G, telecom, networking, C/C++, data structures, and system design.

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Company Overview

Ericsson is a Swedish multinational networking and telecommunications company, and one of the world's three largest 5G equipment vendors (alongside Nokia and Huawei). With 150+ years of innovation, Ericsson builds the backbone of modern mobile communications.

Attribute	Details
Founded	1876 by Lars Magnus Ericsson
Headquarters	Stockholm, Sweden
India Offices	Bangalore, Chennai, Gurgaon (Gurugram), Pune, Noida
Employees	100,000+ globally, 22,000+ in India
Revenue	SEK 264 billion ($25 billion, 2024)
CEO	Börje Ekholm
Business Areas	Networks, Cloud Software & Services, Enterprise Wireless, Technologies
Market Position	#1 or #2 globally in mobile infrastructure (neck-to-neck with Nokia)
5G Contracts	160+ commercial 5G agreements globally

Why Work at Ericsson?

• India is Ericsson's largest R&D center — 22,000+ employees, critical global projects
• 5G leadership — working on cutting-edge technology deployed by carriers worldwide
• Competitive packages — fresher salary ₹6-14 LPA depending on role and campus
• Strong work-life balance — Swedish work culture emphasizes employee well-being
• Global opportunities — rotation programs, international assignments
• Patent culture — 60,000+ patents; engineers contribute to real innovation

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Eligibility Criteria

Parameter	Requirement
Degree	B.E./B.Tech/M.E./M.Tech (CS, IT, ECE, EEE)
CGPA	6.0+ (varies by campus; some require 7.0+)
Backlogs	No active backlogs
Preferred Branches	ECE, CS, IT, EEE — telecom domain knowledge valued

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Hiring Process

Round 1: Online Assessment (60-90 minutes)

• Aptitude: Quantitative, Logical Reasoning, Verbal (20-25 questions)
• Technical MCQs: Networking, C/C++, OS, DBMS, Digital Electronics (20-30 questions)
• Coding: 1-2 coding problems (Easy to Medium)
• Platform: AMCAT, Mercer Mettl, or HackerEarth

Round 2: Technical Interview 1 (45-60 minutes)

• Data Structures & Algorithms
• C/C++ programming (pointers, memory management, STL)
• Computer Networks (TCP/IP, OSI model, protocols)
• Operating Systems (processes, threads, scheduling, memory)
• Project discussion

Round 3: Technical Interview 2 (45-60 minutes)

• Telecom fundamentals (for ECE candidates)
• 5G/4G architecture and concepts
• System design basics
• Advanced programming topics
• Real-world problem-solving scenarios

Round 4: HR Interview (30 minutes)

• Behavioral questions
• Why Ericsson? Why telecom?
• Relocation and shift flexibility
• Salary expectations

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Ericsson Technical Interview Questions with Solutions

Networking & Telecom Fundamentals

Question 1

Explain the TCP/IP model and compare it with the OSI model.

TCP/IP Layer	OSI Equivalent	Function	Protocols
Application	Application + Presentation + Session	End-user services	HTTP, FTP, DNS, SMTP, SNMP
Transport	Transport	End-to-end communication	TCP, UDP, SCTP
Internet	Network	Routing and addressing	IP, ICMP, ARP, OSPF, BGP
Network Access	Data Link + Physical	Physical transmission	Ethernet, Wi-Fi, PPP

Key Differences:

• OSI is a reference model (7 layers), TCP/IP is a practical implementation (4 layers)
• TCP/IP was designed around protocols; OSI was designed before protocols
• TCP/IP's Application layer combines OSI's top 3 layers
• TCP/IP's Network Access combines OSI's bottom 2 layers

Ericsson Context: Ericsson products span all layers — physical (radio units), transport (backhaul), network (IP routing), and application (IMS, VoLTE).

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Question 2

What is the difference between 4G LTE and 5G NR? Explain the architectural changes.

Feature	4G LTE	5G NR
Peak Data Rate	1 Gbps (theoretical)	20 Gbps
Latency	10-30 ms	1-4 ms
Frequency	700 MHz – 2.6 GHz	Sub-6 GHz + mmWave (24-100 GHz)
MIMO	2×2 or 4×4 MIMO	Massive MIMO (64×64, 128×128)
Core Architecture	EPC (Evolved Packet Core) — monolithic	5GC — Service-Based Architecture, cloud-native
Network Slicing	Not supported natively	Native support — multiple virtual networks
Duplex	FDD and TDD	FDD, TDD, Dynamic Spectrum Sharing
Base Station	eNodeB	gNodeB
Beamforming	Basic	Advanced 3D beamforming

5G Deployment Options:

• NSA (Non-Standalone): 5G NR uses existing 4G core (EPC). Faster deployment, limited 5G features.
• SA (Standalone): 5G NR with 5G Core (5GC). Full 5G features including network slicing, URLLC.

Ericsson Context: Ericsson provides complete 5G solutions — Ericsson Radio System (hardware), Ericsson Cloud RAN (software), and Ericsson 5G Core. Their Ericsson Spectrum Sharing technology enables Dynamic Spectrum Sharing between 4G and 5G on the same hardware.

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Question 3

What is OFDM (Orthogonal Frequency Division Multiplexing) and why is it used in LTE/5G?

OFDM divides a wide frequency band into many narrow orthogonal subcarriers. Each subcarrier carries data at a lower rate, and together they achieve high throughput.

Why OFDM?

1. Multipath resistance: Narrow subcarriers are less affected by multipath fading
2. Spectral efficiency: Orthogonal carriers overlap without interference
3. Simple equalization: Per-subcarrier equalization (simpler than time-domain)
4. Flexible bandwidth: Add/remove subcarriers for different bandwidths
5. MIMO compatibility: Works well with spatial multiplexing

5G Enhancement — OFDM with CP (Cyclic Prefix):

• 5G NR uses Scalable OFDM with variable subcarrier spacing (15, 30, 60, 120, 240 kHz)
• Wider spacing for mmWave (handles Doppler shift better)
• Narrower spacing for sub-6 GHz (better spectral efficiency)

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Question 4

Explain the concept of Network Slicing in 5G.

Network Slicing creates multiple virtual networks on a single physical infrastructure, each optimized for specific use cases.

Example Slices:

Slice	Use Case	Requirements
eMBB Slice	Video streaming, broadband	High throughput (1 Gbps+), moderate latency
URLLC Slice	Autonomous vehicles, remote surgery	Ultra-low latency (<1 ms), 99.999% reliability
mMTC Slice	IoT sensors, smart meters	Massive connections (1M devices/km²), low power
Enterprise Slice	Private 5G for factory	Guaranteed QoS, security isolation

Implementation:

1. RAN Slicing: Share radio resources, prioritize per slice
2. Transport Slicing: VLAN/MPLS-based traffic separation
3. Core Slicing: Dedicated or shared network functions per slice
4. Management: Slice lifecycle management (creation, modification, deletion)

Ericsson Solution: Ericsson's Dynamic Orchestration platform manages network slices end-to-end.

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Data Structures & Algorithms

Question 5

Given a string, find the length of the longest substring without repeating characters.

#include <string>
#include <unordered_map>
using namespace std;

int lengthOfLongestSubstring(string s) {
    unordered_map<char, int> charIndex;
    int maxLen = 0, left = 0;
    
    for (int right = 0; right < s.size(); right++) {
        if (charIndex.count(s[right]) && charIndex[s[right]] >= left) {
            left = charIndex[s[right]] + 1;
        }
        charIndex[s[right]] = right;
        maxLen = max(maxLen, right - left + 1);
    }
    
    return maxLen;
}

// Time: O(n), Space: O(min(n, charset_size))
// Sliding Window technique

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Question 6

Implement a function to check if a binary tree is a valid BST.

struct TreeNode {
    int val;
    TreeNode *left, *right;
};

bool isValidBST(TreeNode* root, long minVal = LONG_MIN, long maxVal = LONG_MAX) {
    if (!root) return true;
    
    if (root->val <= minVal || root->val >= maxVal)
        return false;
    
    return isValidBST(root->left, minVal, root->val) &&
           isValidBST(root->right, root->val, maxVal);
}

// Time: O(n), Space: O(h) where h = height

Alternative — Inorder traversal should give sorted sequence:

bool isValidBST_inorder(TreeNode* root) {
    stack<TreeNode*> stk;
    TreeNode* prev = nullptr;
    
    while (root || !stk.empty()) {
        while (root) {
            stk.push(root);
            root = root->left;
        }
        root = stk.top(); stk.pop();
        
        if (prev && root->val <= prev->val)
            return false;
        
        prev = root;
        root = root->right;
    }
    return true;
}

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Question 7

Implement Dijkstra's shortest path algorithm.

#include <vector>
#include <queue>
using namespace std;

vector<int> dijkstra(int n, vector<vector<pair<int,int>>>& adj, int src) {
    vector<int> dist(n, INT_MAX);
    // Min-heap: {distance, node}
    priority_queue<pair<int,int>, vector<pair<int,int>>, greater<>> pq;
    
    dist[src] = 0;
    pq.push({0, src});
    
    while (!pq.empty()) {
        auto [d, u] = pq.top();
        pq.pop();
        
        if (d > dist[u]) continue;  // Skip outdated entries
        
        for (auto [v, w] : adj[u]) {
            if (dist[u] + w < dist[v]) {
                dist[v] = dist[u] + w;
                pq.push({dist[v], v});
            }
        }
    }
    
    return dist;
}
// Time: O((V + E) log V), Space: O(V)

Ericsson relevance: Routing protocols like OSPF use Dijkstra's algorithm (SPF — Shortest Path First) to compute optimal routes in IP networks.

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C/C++ Programming

Question 8

Explain the difference between malloc and new in C++.

Feature	malloc	new
Type	C library function	C++ operator
Return Type	void* (needs casting)	Correct type (no casting)
Constructor	Not called	Called automatically
Failure	Returns NULL	Throws std::bad_alloc
Size	Manual: malloc(sizeof(Type))	Automatic: new Type
Deallocation	free()	delete / delete[]
Overloadable	No	Yes (operator new)
Initialization	No initialization	Can initialize (new int(5))

// malloc — C style
int* p1 = (int*)malloc(sizeof(int) * 10);
free(p1);

// new — C++ style
int* p2 = new int[10]();  // Zero-initialized
delete[] p2;

// For objects — always use new (calls constructor)
class MyClass { public: MyClass() { /* init */ } };
MyClass* obj = new MyClass();  // Constructor called
delete obj;                     // Destructor called

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Question 9

What are smart pointers in C++? Explain unique_ptr, shared_ptr, and weak_ptr.

Smart pointers manage memory automatically, preventing memory leaks.

#include <memory>

// unique_ptr — exclusive ownership, no copying
{
    auto p = std::make_unique<int>(42);
    // auto p2 = p;  // ERROR! Cannot copy
    auto p2 = std::move(p);  // OK — transfer ownership
}  // Memory freed when p2 goes out of scope

// shared_ptr — shared ownership, reference counting
{
    auto p1 = std::make_shared<int>(42);  // ref_count = 1
    {
        auto p2 = p1;  // ref_count = 2
    }  // p2 destroyed, ref_count = 1
}  // p1 destroyed, ref_count = 0, memory freed

// weak_ptr — non-owning reference (breaks circular references)
{
    auto shared = std::make_shared<int>(42);
    std::weak_ptr<int> weak = shared;
    
    if (auto locked = weak.lock()) {
        // Use locked (shared_ptr) — safe to access
    }
}

When to use:

• unique_ptr: Default choice. Single owner. Factory functions, RAII.
• shared_ptr: Multiple owners needed. Shared data structures.
• weak_ptr: Break circular references. Cache, observer pattern.

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Operating Systems

Question 10

Explain process scheduling algorithms. Which is used in modern OS?

Algorithm	Type	Description	Pros	Cons
FCFS	Non-preemptive	First Come, First Served	Simple	Convoy effect
SJF	Non-preemptive	Shortest Job First	Min avg wait	Starvation of long jobs
SRTF	Preemptive	Shortest Remaining Time	Optimal avg wait	Starvation, overhead
Round Robin	Preemptive	Time quantum rotation	Fair, no starvation	Context switch overhead
Priority	Both	Based on priority value	Flexible	Starvation (solved by aging)
MLFQ	Preemptive	Multiple RR queues with priorities	Adaptive, balanced	Complex
CFS	Preemptive	Completely Fair Scheduler (red-black tree)	Fair CPU time	Complex

Modern Linux uses CFS (Completely Fair Scheduler):

• Uses a red-black tree sorted by "virtual runtime"
• Process with least vruntime runs next
• Weighted by nice value (priority)
• O(log n) for picking next process

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Question 11

What is a semaphore? How is it different from a mutex?

Feature	Mutex	Semaphore
Purpose	Mutual exclusion (1 thread at a time)	Counting resource access (N threads)
Values	Binary (locked/unlocked)	Integer (0 to N)
Ownership	Yes — only owner can unlock	No — any thread can signal
Type	Binary	Binary or Counting
Use Case	Critical section protection	Resource pool management, producer-consumer

#include <mutex>
#include <semaphore>  // C++20

// Mutex — protect shared resource
std::mutex mtx;
void critical_section() {
    std::lock_guard<std::mutex> lock(mtx);
    // Only one thread executes here
}

// Counting Semaphore — limit concurrent access
std::counting_semaphore<3> sem(3);  // Allow 3 concurrent
void limited_resource() {
    sem.acquire();  // Decrement (wait if 0)
    // At most 3 threads here
    sem.release();  // Increment
}

// Producer-Consumer with Semaphore
std::counting_semaphore<10> empty_slots(10);
std::counting_semaphore<10> full_slots(0);

void producer() {
    empty_slots.acquire();  // Wait for empty slot
    // Produce item
    full_slots.release();   // Signal item available
}

void consumer() {
    full_slots.acquire();   // Wait for item
    // Consume item
    empty_slots.release();  // Signal slot freed
}

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System Design

Question 12

Design a network monitoring system for telecom infrastructure.

Requirements:

• Monitor 100,000+ network elements (routers, base stations, switches)
• Collect metrics every 5-15 seconds (CPU, memory, traffic, signal quality)
• Real-time alerting on failures
• Historical data for trend analysis
• Dashboard for NOC (Network Operations Center)

Architecture:

Network Elements → SNMP/gRPC Collectors → Message Queue (Kafka) →
                                              ↓
                              Stream Processor (Flink/Spark Streaming)
                              ↓                    ↓
                     Time-Series DB           Alert Engine
                     (InfluxDB/Prometheus)    (Rules + ML)
                              ↓                    ↓
                     Grafana Dashboard       Notification
                                            (Email/SMS/PagerDuty)

Key Design Decisions:

Component	Choice	Rationale
Collection	SNMP (legacy) + gRPC (new)	SNMP for existing devices, gRPC for modern 5G elements
Message Queue	Kafka	High throughput, fault-tolerant, ordered by partition
Processing	Apache Flink	Real-time stream processing, complex event processing
Storage	InfluxDB + cold storage (S3)	Optimized for time-series, auto-downsampling for old data
Alerting	Rule engine + anomaly detection ML	Rules for known patterns, ML for unknown anomalies

Scale: 100K devices × 50 metrics × 12 samples/minute = 60M data points/minute → Kafka partitioning + Flink parallelism handles this.

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Preparation Strategy

30-Day Ericsson Prep Plan

Week 1: CS Fundamentals

• Networking: OSI, TCP/IP, protocols (HTTP, DNS, DHCP, ARP)
• OS: Processes, Threads, Scheduling, Memory Management
• DSA: Arrays, Strings, LinkedList, Stack, Queue

Week 2: Advanced Topics

• Networking: Routing (OSPF, BGP), Subnetting, VLANs, NAT, Firewalls
• DSA: Trees, Graphs (BFS, DFS, Dijkstra), Hashing, DP
• C/C++: Pointers, Memory, STL, Smart Pointers, Virtual Functions

Week 3: Telecom & Domain

• 5G/4G fundamentals, OFDM, MIMO, Network Slicing
• Telecom basics: GSM → 3G → 4G → 5G evolution
• Ericsson products research: Ericsson Radio System, Cloud RAN, 5G Core

Week 4: Practice & Mock

• Solve previous Ericsson papers
• 2-3 mock interviews
• Behavioral preparation (STAR format)
• Research recent Ericsson news (5G deployments, Open RAN)

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Related Preparation Guides

• Nokia Placement Papers 2026 — Direct competitor, similar questions
• TCS Placement Papers 2026 — IT services campus hiring
• Infosys Placement Papers 2026 — Campus hiring preparation
• Postman Placement Papers 2026 — API/networking focus
• 30-Day Placement Preparation Plan — Structured preparation

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Frequently Asked Questions

Q: What is the fresher salary at Ericsson India? A: Software Engineer/Network Engineer roles for freshers range from ₹6-14 LPA depending on role, campus tier, and location. R&D positions in Bangalore typically offer higher packages.

Q: Does Ericsson prefer ECE over CS students? A: Ericsson values both. ECE students have an edge for network engineering, radio, and hardware roles. CS students are preferred for cloud, software development, and automation roles. Networking knowledge is valued across both.

Q: What programming languages should I focus on? A: C and C++ are most important (core network systems). Python for automation and tooling. Java for cloud-native services. Go is increasingly used for new microservices.

Q: How important is telecom domain knowledge? A: Very important for Ericsson interviews. Understanding 5G basics (architecture, OFDM, MIMO, network slicing) significantly improves your chances, especially for R&D roles.

Q: Does Ericsson offer international opportunities? A: Yes. Ericsson has a global rotation program and frequently offers international assignments. India engineers regularly collaborate with teams in Sweden, US, and other countries.

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Last Updated: March 2026