1. Village Communication Network Leveraging on Fibre to the Village Researcher: Vishal Sevani Faculty: Bhaskaran Raman, Abhay Karandikar TCOE IITB Researcher: Jyoti Purohit Faculty: Ashok Jhunjhunwala TCOE IITM

2. Motivation: Rural Broadband Scenario House Community centre School Village: 2-3km diameter Tablet (Aakaash) Fibre optic access close to village: ~5km Need: cost effective last mile connectivity Applications: rural education, healthcare, IT services

3. Solution Choices Running cables High cost WiMAX, LTE High cost Requirement of tall tower High power consumption Wi-Fi based network License free band Low equipment cost Low power consumption: <10W, solar power possible

4. Long-Distance WiFi versus WiFi Mesh High cost of tall tower Hidden terminal issues Fault tolerance issues “On the Feasibility of the Link Abstraction in (Rural) Mesh Networks”, D. Gokhale, S. Sen, K. Chebrolu, and B. Raman, INFOCOM 2008 Insight: outdoor mesh network links can be stable, TDMA MAC feasible

5. Solution Choices Running cables High cost WiMAX, LTE High cost Requirement of tall tower High power consumption Long-distance WiFi High cost of tower Wi-Fi based multi-hop mesh network License free band Low equipment cost Low power consumption: <10W, solar power possible Low cost installation on light poles, roof-tops Self configurable Potential to enable “sustainable village franchise” model

6. Solution Approach: WiFi Mesh House Community centre School Village: 2-3km diameter Tablet (Aakaash) Fibre optic access close to village: ~5km (2) WiFi-PHY based link (1) Low-cost commodity WiFi hardware (3) Multi-hop mesh network running TDMA-based LiT MAC

7. Technical Challenges and Solution Commodity Wi-Fi has CSMA/CA Poor performance in multi-hop mesh Poor throughput, delay: cannot support real- time applications Solution: TDMA-based MAC called LiTMAC – Light-weight TDMA MAC

8. Accomplishments Implementation of TDMA based LiTMAC protocol for WiFi-PHY based mesh network – Modifications to open source ath9k driver – Testing and bug-fixing of LiTMAC implementation – Code runs stably for long durations of time – Implementation of the per-hop ack: performance improvement in presence of wireless packet losses Ported the software on the low cost Ubiquiti bullet M2HP platform Testing the solution in lab setting & test deployment

9. Performance Evaluation Setup Root Infra1Infra3Infra2 LitMAC WiFi CSMA WiFi Aakash Tablet Ethernet

10. Performance Results

11. Future Work Other features in LiTMAC implementation – Ease of configuration of various LiTMAC parameters – Dynamic routing, dynamic scheduling Identify solar-power solution for the WiFi nodes Detailed field deployment evaluation of LiTMAC in rural settings Identify any modifications required in LiTMAC to further improve the efficiency With LiTMAC code, run pilot commercial network, in co-operation with ISP to provide broadband Internet connectivity