Packet radio networks allowed multiple wireless terminals on a battlefield to communicate with one another using packet switching technology over broadcast radio networks. This was developed by DARPA and used in battlefields, laying the foundation for modern wireless local area networks. Key challenges included flow and error control over wireless links, maintaining network topology as routers moved, and managing shared channel access among users with limited processing power. Packet radio networks addressed these by using mobile radio repeaters to relay packets between destinations, deriving routes, and employing carrier sense multiple access with acknowledgments.

1. Packet Radio
Networks

2. Introduction
 Several wireless terminals could communicate with one another on a
battlefield.
 Packet radio was a technology that extended the concept of packet
switching (which evolved from point-to-point communication networks) to
the domain of broadcast radio networks.
 DARPA used this in the battlefield, which is the fundamental for WLAN.
 Routers themselves are mobile.

3. Challenges in PRNET
 Flow control over a wireless multi-hop communication route
 Error control over wireless links
 Deriving and maintaining network topology information
 Deriving accurate routing information
 Mechanisms to handle router mobility
 Shared channel access by multiple users
 Processing capability of terminals
 Size and power requirements

4. PRNET

5. PRNET
 Mobile radio repeaters,
 relay packets from one repeater to another, until the packets eventually reach
the destination host
 wireless terminals, and
 to derive routes from one host to another
 dedicated mobile stations

6. PRNET

7. PRNET
 It uses CSMA
 Passive and active acknowledgements