INTRODUCTION TO VANET
Vehicular Ad-hoc Networks (VANETs) are a key component of
Intelligent Transportation Systems (ITS). They allow vehicles to
communicate with each other (V2V), with roadside infrastructure (V2I),
and with other entities (V2X) in real-time.
Origin and Evolution
The concept of VANETs was proposed in 2001 by Chen, Kung, and Vlah to
enable vehicle and infrastructure information sharing. In 2013, the US
Department of Transportation and automotive manufacturers tested V2V
communication for safety applications. With 5G, VANET interactions
expanded beyond V2V and V2I to include communication with drivers,
pedestrians, cloud servers etc.
Applications
VANETs enable a variety of applications:
Safety applications - collision avoidance, emergency warnings
Traffic management - traffic optimization, route planning
Driver assistance - navigation, parking assistance
Infotainment - internet access, media streaming
Urban sensing - gathering and sharing data about road conditions
Features
Some key features of VANETs:
Highly dynamic topology due to vehicle mobility
Frequent disconnections as nodes move out of range
Geographical addressing based on position rather than ID
Limited mobility predictability based on roads, speed limits etc.
Challenging wireless propagation environments
Routing Protocols and Security
Various routing protocols and security considerations exist for VANETs. Key
protocols include DSDV, AODV, DSR. Security aspects include availability,
authentication, privacy, integrity.
Mobility Models and Implementation
Mobility models like Gauss-Markov model the movement patterns of
vehicles. VANETs can be implemented through simulations and testbeds
using various hardware/software platforms.
BEAM FORMING IMPACT ON THE NEXT GENERATION WI-FI
IEEE802.11AY IN MM WAVE FREQUENCY BAND
Key Points
IEEE 802.11ad provided high data rates but limited range at 60 GHz
frequency band
802.11ay introduced to achieve 100 Gbps data rates and 300-500m
range through:
Increased channel bandwidth (8.64 GHz vs 2.16 GHz in
802.11ad)
Multi-stream transmission
Advanced beamforming
802.11ay can provide wireless backhaul for small cells in 5G
heterogeneous networks
60 GHz mmWave suffers from high path loss, absorption, poor
obstacle penetration
High gain antenna arrays with beamforming used to compensate
path loss
Large number of antenna elements needed for narrow, directional
beams
Phase/amplitude of each element controlled for fast, precise beam
steering
2D and 3D beamforming algorithms generate directional beams
Beams can be steered to target specific locations/devices
Uniform linear arrays (ULA) and uniform rectangular arrays (URA)
analyzed
Increasing antenna elements narrows beamwidth, increases range
URA well-suited for 802.11ay networks to overcome signal blocking
Key Highlights
802.11ay's higher bandwidth, multi-stream, and advanced
beamforming enables 100 Gbps speeds and longer range
It can provide wireless backhaul for small cells in 5G, replacing
costly wired backhaul
Beamforming with antenna arrays is essential to overcome 60 GHz
propagation challenges
ULAs and URAs allow flexible beam shaping and steering to optimize
signals
Increasing antenna elements boosts directionality and minimizes
path losses
802.11ay and mmWave will be key technologies enabling high data
rates in future wireless networks
