Hydra:

A Wireless Multihop Testbed

A collaborative effort between Drexel University and the WNCG with support from NI, TI, Intel, and the NSF presented by Ketan Mandke Fall 2005 The 2005 Texas Wireless Symposium

What is Hydra?

  Wireless Multihop Testbed  Tool to investigate multiple-antenna multihop network  Designed with flexible RF, PHY, and MAC Collaborative Effort    Multi-pronged development MAC & PHY – WNCG at UT RF – Drexel University

Motivation

 Why should we build prototypes?

   Gap between research and practical engineering  Research supported by simulation and analysis with many assumptions  Practical systems must often break assumptions in research Simulation is not enough!

 Real world can be prohibitively complicated to model completely Prototyping can bridge the gap between theory and practice

Motivation (cont.)

 Why is it important to build a flexible and easy-to-modify prototype?

  Problem: support a broad range of research Solution: make Hydra as flexible as possible   Flexibility enabled through reconfigurable design  PHY implemented using NI LabVIEW  MAC and Network implementation using Click modular router Hydra has multiple degrees of freedom  Multiple antennas   OFDM Cross-layer design

Motivation (cont.)

 What kind of research do we want to explore using Hydra?

  Implement current research in real world prototype    Rate adaptive protocols (e.g. RBAR, OAR) Closed-loop MIMO systems Multiple antenna MAC protocols (MIMA-MAC) Design new cross-layer algorithms  MAC and PHY algorithms for multiple-antenna multihop networks

Hydra Node: Block Diagram

RF Implementation

  Equipment   Texas Instruments (RCS 110) RF transceiver cards Conformal or standalone antenna array Features  Multiband operation (ISM and UNII)

PHY Design

    2x2 MIMO OFDM  Based on IEEE 802.11a

Up to 20 MHz Bandwidth Variable Data Rates (up to 108Mbps) Multiple MIMO modes  Spatial Multiplexing and Transmit Diversity

PHY Implementation

    D/A – NI PXI-5421 Arbitrary Waveform Generator A/D – NI PXI-5122 High-Speed Digitizer Embedded PC, A/D, D/A live on NI PXI Chassis Software implemented in NI LabVIEW

PHY Design – LabVIEW Virtual Instrument Block

MAC Design

 DCF mode of IEEE 802.11 MAC   Flexible interface to PHY through ethernet connection Interfaces with IP stack (i.e. interoperability with IP, TCP, application layer)

MAC Implementation

  Software implemented in a general purpose host running Linux Implemented using

Click

- modular software router developed by MIT’s Parallel & Distributed Operating Systems Group

Hydra Status

   Successful end-to-end application layer testing Attempting to increase throughput by reducing processing time Current Cross-Layer Research  Rate Adaptive MAC  Closed-loop MIMO communication

Hydra in Action

Sponsors

The National Science Foundation National Instruments Texas Instruments Intel Office of Naval Research

Principal Investigators

Personnel

Students

Kapil Dandekar – Drexel University Nicholas Kirsch, Matt Garfield Robert Heath – WNCG (UT) Scott Nettles – WNCG (UT) Robert Daniels, Robert Grant, Johann Chiang Soon-Hyeok Choi, Ketan Mandke, Gibeom Kim