COURSE NAME :- WIRELESS COMMUNICATION
COURSE CODE :- BTEC – 601 – 18
ASSIGNMENT NO :- 3
DATE OF ALLOTMENT :- 15-04-2025
DATE OF SUBMISSION :- 18-04-2025
COURSE INSTRUCTOR :- DR. GHANISHTHA
SUBMITTED BY :- HARSHDEEP MAAN
REGISTRATION NO. :- 2201649
Question 1:- Write a note on third generation wireless network and standards.
Answer:- Third Generation (3G) Wireless Networks
3G networks mark a major leap in mobile communication technology, introduced to
improve data speed, quality of service, and connectivity. Emerging in the early 2000s, 3G
made internet access on mobile devices more efficient, enabling services like video chats,
online browsing, and multimedia messaging.
Salient Features of 3G:-
1. Maximum data rates of around 2 Mbps for users with minimal movement.
2. Support for integrated voice, data, and multimedia services.
3. Better use of bandwidth and increased network capacity.
4. Seamless international roaming and global coverage.
3G Standards under IMT-2000 :--
The ITU's IMT-2000 framework outlines various 3G standards developed across
different regions:-
UMTS (Universal Mobile Telecommunications System) :--
1. Spearheaded by 3GPP.
2. Employs W-CDMA technology.
3. Commonly deployed in Europe and several parts of Asia.
CDMA2000:-
1. Developed by 3GPP2.
2. Built upon the existing CDMA infrastructure.
3. Predominantly used in North America and parts of Asia.
TD-SCDMA:-
1. Developed in China as a homegrown solution.
2. Combines time division and synchronous CDMA techniques.
Uses of 3G Technology:-
1. Web surfing on mobile phones.
2. Real-time video calls.
3. Location-based services and navigation.
4. Streaming mobile TV and playing online games.
Question 2:- Short questions
i) Advantages of RAKE receiver :-
1. Enhances reception by combining multiple delayed signal paths.
2. Improves signal integrity by mitigating multipath fading.
3. Increases reliability and robustness in CDMA systems through signal diversity.
ii) IS-136 standard :-
IS-136, also known as D-AMPS, is a second-generation digital mobile system based on
TDMA. It facilitated digital voice calls, messaging, and limited data services, mainly in
North America.
iii) Dwell time :-
Dwell time is the duration a mobile device stays tuned to a specific frequency or channel
before switching due to handover or interference.
iv) Role of the power control bit in CDMA :-
It dynamically regulates the transmission power of mobile devices, helping maintain
optimal signal strength while reducing interference in the network.
v) List the GSM channels :-
1. Traffic Channel (TCH)
2. Broadcast Control Channel (BCCH)
3. Common Control Channel (CCCH)
4. Dedicated Control Channel (DCCH)
5. Paging Channel (PCH)
6. Random Access Channel (RACH)
7. Synchronization Channel (SCH)
vi) Services provided by GSM :-
1. Voice communication
2. Text messaging (SMS)
3. Mobile internet access (GPRS/EDGE)
4. Roaming support
5. Call waiting, forwarding, and barring
6. Caller identification and voicemail
vii) Reverse CDMA channel
The reverse channel in CDMA refers to the uplink, where data and control signals are
sent from the user's mobile device to the base station.
Question 3:- Draw and Explain IS-95 forward link in detail.
Answer:-
IS-95 Forward Link (Base Station to Mobile):-
The forward link in IS-95 CDMA refers to the downlink transmission from the base
station to the mobile user. It operates on a single frequency band, with different data
streams separated using orthogonal Walsh codes.
Components of the Forward Link:-
Pilot Channel:-
1. Transmits no actual data.
2. Assists with synchronization and signal strength estimation.
3. Uses a fixed Walsh code (usually code 0).
Synchronization (Sync) Channel:-
1. Provides network identity and timing info.
2. Allows mobile devices to align with the system clock.
Paging Channel:-
1. Broadcasts control information, including call alerts and system messages.
2. Shared among multiple users.
Traffic Channels:-
1. Carry individual user data such as voice or internet traffic.
2. Each user receives a unique Walsh code.
Key Features:-
1. All users transmit on the same carrier frequency.
2. Orthogonal codes eliminate intra-cell interference.
3. QPSK (Quadrature Phase Shift Keying) used for modulation.
4. Supports soft handoff for better mobility handling.
Question 4:- Draw and Explain GSM signal processing in detail.
Answer :- GSM signal processing converts user speech into a modulated radio signal
suitable for wireless transmission. The entire process ensures data integrity, security, and
efficiency.
Steps in GSM Signal Processing:-
Speech Encoding:-
1. Transforms analog voice into digital form using RPE-LTP coding.
2. Typical output rate:- 13 kbps.
Channel Encoding:-
1. Adds redundant bits for error correction using convolutional and block coding.
2. Protects data from wireless transmission errors.
Encryption (Ciphering):-
1. Encrypts the data stream using encryption algorithms (e.g., A5 series).
2. Maintains communication confidentiality.
Interleaving:-
1. Spreads bits across multiple frames to reduce impact of burst errors.
Burst Mapping:-
1. Formats data into time-slot bursts including training sequences and guard periods.
Modulation:-
1. Uses GMSK modulation for transmitting constant-envelope signals.
Radio Transmission:-
1. The signal is upconverted to a radio frequency and sent via the antenna.
Reception Path (Reverse Process):-
- Demodulation → Burst detection → De-interleaving → Decryption → Decoding →
Speech reconstruction
