Mobile Network Field Testing at HMP-2000 zy Bruce L. Gilbaugh*, Brian Glass?, Richard AlenaS NASA-Ames Research Center Moffett Field, CA 94035 zyxwv bgilbaugh@mail.arc.nasa.gov 650-604-428 1 Abstract-Future human planetary exploration field teams will need daily communications with their base and with mission control. A remote field wireless digital network will be a requirement for safe and productive human exploration. Proper selection of radio-frequency hardware and antennas will be vital to its success in remote, hostile environments. This paper reviews the communications techniques explored in the Mobile Exploration 2000 field season at the Haughton-Mars Project, which was located at a remote impact crater field science site in the Canadian Arctic. Results from 2.4GHz spread-spectrum signal- strength and data throughput tests, conducted during remote field deployments, show a marked variability with given hardware and antenna choices, with directional antenna performance less than expected from theory. Changing the antenna schemes for repeater-to-base and repeater-to-rover increased the rover’s effective communication range to base camp to over 3km. TABLE OF CONTENTS 1. INTRODUCTION 2. EQUIPMENT BACKGROUND 3. SPREAD SPECTRUMTECHNOLOGY 4. ANTENNA BASICS 5. THE REPEATER-TO-BASE zyxwvutsrq CAMP ANTENNA 6. THE REPEATER-TO-ROVER ANTENNA 7. THE ROVER ANTENNAS 8. CONCLUSION zyxwvutsrq 1. INTRODUCIION While NASA has achieved the goal of reaching the Moon, more distant planet exploration will require not only new technologies but new ways of thinking and communicating. Three basic elements are required for rehearsal of manned explorations to other planets. Members of a future manned planetary exploration group need to practice daily activity planning and reporting sessions for routine transmission * Communications Engineer ? Senior Staff Scientist $ Computer Engineer Standard IEEE Copyright zyxwvutsrqpo “0-7803-6599-2/01/$10.00 zyxwvutsrqp 0 2001 IEEE, U.S. Government work not protected by U.S. copyright. along with emergency communications scenarios to Mission Control. Scientists must provide an environment that closely resembles the surface of the planet to be visited as well as knowledge of the effects of local gravity, etc. Lastly, a place where the only things you have are what you bring with you. Having done just that this field season at the Haughton-Mars Project in the Wilderness of Nunavut, Canada, this paper will review the communications infrastructure and techniques explored. Six years ago work based at NASA’s Ames Research Center proved that a wireless network was functionally practical in space by placing three laptop computer systems, a wireless access point, and two client PCMCIA transceiver cards aboard the Mir space station and successfully exchanging data between the three onboard computer systems using the wireless interfaces. Based upon the high degree of success of the Mir experiment, the implementation of a wireless network for keeping astronauts on manned planetary explorations in touch with their home base and ultimately with Mission Control using the proven wireless technology base was born. The Mobile Exploration Project (MEX) at Ames Research Center is designed to evaluate wireless technologies and explore their potential integration through simulations for the requirements of data, voice over IP, videoconference collaboration, and scientific data software applications. Ames’ mobile architecture testbed is designed to integrate different components into a unified system and is currently under construction. For the past two years the MEX Project has been evaluating the use of FHSS (Frequency Hopping Spread-Spectrum) and DSSS (Direct Sequence Spread-Spectrum) network products to extend the wired capability of the Base Camp network computing LAN into the field. [ 1,2] 2. EQUIPMENT BACKGROUND Typically this technology has been typically limited to a maximum range of 1000 feet in an outdoor setting with an unobstructed Line of Site (LOS). The basic specification for the radio transmitters providing this range was 1/10 Watt RF output into a dipole antenna. The maximum range attained for field seasons 1998 and 1999 was limited to just one quarter of a mile or 1,320 feet. This included the use of a repeater for extended range as well which should have provided a range of at least 1,600 feet or just over one third of a mile. Analysis of the equipment used to create the wireless network lead to one primary area that was determined to be incorrectly specified for such an application. High gain omni-directional antennas were 3-1085