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					  Locally Networked Satellite-Based Computer Labs for Tanzanian
                            Classrooms




                                      Final Proposal
                                     February 20, 2009



                                       Sponsored By:




                                    In Cooperation With:




University of Dar es Salaam                                    Michigan State University



                        ECE 480 – Design Team #2 – Spring 2009
                              Management      Brian Holt
                                Webmaster     Daniel Newport
                           Document Prep.     Steven Sadler
                          Presentation/ Lab   Kevin Bishop
Executive Summary
        With the increasing dependency on technology there is a great demand to develop
affordable personal computers for remote and undeveloped areas. One potential region is rural
East Africa, specifically Tanzania. Before deploying a computer system into such harsh
conditions several obstacles must be overcome, including providing a reliable source of
electricity to the system, telecommunications, and the savannah climate. The Lenovo
Corporation has tasked this team to develop a computer workstation that can accommodate up to
eight users. The solution must be robust enough to withstand the harsh environment and also be
affordable for rural schools.




                                              1
                             TABLE OF CONTENTS
Technical Section

       Introduction……………………....Page 3

       Background……………………....Page 5

       Design Criteria…………………...Page 6

       Conceptual Design……………….Page 7

       Ranking of Conceptual Design…..Page 10

Project Management Section

       Project Management Plan………..Page 14

Costs Section

       Approximate Costs…………..…...Page 15

Fast Diagram/ References

       Fast Diagram………………..……Page 16

       References………………………..Page 16




                                           2
Introduction

        Many schools in rural Africa are without computers and network access, and have almost
no books for their students to use. Having internet access could greatly improve the current
situation of these schools. However, many schools are in locations with no electrical service or
network connectivity. While we may not be able to purchase books for these schools we are able
to provide a means to improve their education via computers and the use of the internet.

        Lenovo has chosen to support the development of an eight-seat multi-user computer
workstation complete with network access. Since installing a computer system in rural Africa
will present many issues we will attempt to simulate, and educate ourselves as much as possible
on, as many of these issues as possible prior to our arrival in Tanzania.

         We will begin this semester’s project by reviewing the previous semesters efforts to
install a similar system in Tanzania. While there are a few differences between the two projects,
such as the previous teams use of solar power, we believe we can use the previous project in
order to evaluate what measures they took in order to successfully install their system in
Tanzania, issues that they dealt with and had to overcome, and what we can do to improve upon
the previous design.

       The following is the main criteria that we must consider in order to implement a
successful project design by May 9th, our scheduled deployment date.

      The system that we install must be robust and be able to perform under any weather
       condition. This system must be reliable in heat that is typical in Africa, with an average
       year round temperature of 85 degrees Fahrenheit and average highs of 110 degrees
       Fahrenheit.
      The system must also be able to operate under the most unpredictable of power
       conditions. The secondary school that we will be installing this system in has access to a
       power grid, however, that grid is subject to unpredictable power outages ranging in time
       from a couple of minutes to full days. This power grid is also subject to varying voltages,
       which could be harmful to the computer system and its components.
      This system must be as maintenance free as possible. We are installing this system in an
       area where neither the teachers nor the students have any previous experience with
       operating a computer. If problems were to occur within the system debugging and fixing
       these problems may not be possible for large amounts of time.
      We will be routers equipped with modified antennas to create the gain and signal strength
       necessary to accomplish the task of internet connectivity between location of the primary
       school that last semesters team installed a workstation at and this semesters location at
       the secondary school, which are separated by approximately two miles.
      We are also designing this system so that it may easily be expanded beyond the two
       schools that will have network access upon completion of this semester’s project. With



                                                3
the current multi seat system we are designing we will have two computers each
equipped with the ability to accommodate up to four users per computer. We are also able
to easily expand upon the current network connections due to the fact that the proposed
antenna design is capable of sending a usable signal up to five miles.




                                       4
Background
        In the fall semester of 2008 the Lenovo Corporation made a unique opportunity available
to a design team in ECE 480. The task would be to introduce a low cost, low maintenance, solar
powered Linux based computer workstation into a primary school in rural Africa capable of
seating up to eight users. The team would face many obstacles while preparing to deploy the
system including the savannah climate, telecommunication and the lack of a reliable form of
electricity within the village in which the school was located. The team was able to use solar
panels to charge a small battery bank, which included a custom engineered management system
to monitor voltages and currents from the solar panels and the battery. The system was also able
to monitor the temperature within the case that stores the batteries and monitoring system, to
ensure that the system is shut down if an unsafe temperature is reached within the case.

        This semester Lenovo Corporation has given our team the task of developing a similar
computer workstation, also capable of accommodating up to eight users. This workstation will
again be entered into the harsh climate of Tanzania but, contrary to last year’s workstation, will
accommodate users in a secondary school, approximately two miles from the primary school
location from last semester. However, this semester we will be able to utilize the fact that the
secondary school is located on the power grid.

        While we are fortunate that the secondary school is located on the power grid we are still
forced to do with the reoccurring problem of unreliable power since this grid is subject to
unpredictable “blackouts” and varying voltages. To conquer the power problems we will incur
while attempting to place the workstation in Tanzania we will use an uninterruptible power
supply (UPS) system to charge a small battery bank, which will be used to run the workstation
when the power from the grid is unavailable. This will allow us to ensure that brief power
disruption does not cause injuries, data loss, or system failure. In the event that power is no
longer available from the grid the UPS will allow the user to continue normal operation on the
workstation for up to four hours. Ideally the UPS will include a monitoring system to warn the
user that the battery bank is running low, in order to ensure that important data is saved and the
proper shut down procedure is done in the event that power from the grid is not restored.

         This semester we will also be installing modified antennas to two routers, one that will be
placed at the primary school and one at the secondary school. These antennas will allow us to use
the satellite router that was previously installed in the primary school location and access the
internet at the new location, which is approximately two miles away. We will also be moving the
satellite router to the secondary school, in order to release some of the power draw from the solar
power system.
         This project will be completed throughout the course of this semester and will be
installed by the members of our team, as well as several members from the previous semesters
team, into the Tanzanian secondary school beginning on May 9th, 2009.




                                                 5
Design Criteria
     Low cost (priority: 4) – This is the most important design criteria. Since this system is
      being designed for Third World countries to purchase, the cost needs to be as low as
      possible. In particular, the computing solution will be designed to minimize the cost per
      seat. Also, normal (store bought) wireless routers with modified firmware will be
      attached to high-gain directional antennas so that a single internet connection can be
      shared amongst multiple areas (schools).

     Low maintenance (priority: 3-4) – Also one of the more important criteria. These
      systems are being designed for areas that will have little to no available support. Thus,
      they must be designed for robustness and require little maintenance. All materials used
      for the antenna will be designed to handle a the expected harsh conditions. Furthermore,
      the computing solution will be user friendly and secure. The uninterruptible power
      supply (UPS) will help shield the computer from fluctuations in power, and the UPS
      itself will be designed to handle an unpredictable energy supply.

     Low power consumption (priority: 1-2) – Low power usage is less of an issue than in the
      Fall 2008 project, however, a system that achieves this will increase the uptime of the
      UPS should the power fail. The multi-seat computer system will help make this system
      use less power by consolidating the required electronics into a single PC.

     Safety (priority: 3-4) – Safety is a high priority in more than just the physical sense. One
      of the primary means of accomplishing this is the use of a white list on the computing
      system to help control the content that school-aged children are allowed to view. The
      white list will also make the system more maintainable by blocking sites that could
      harbor malicious code. Also, the development of appropriate content for the system will
      allow for an enriching yet safe experience.

     Expandability (priority: 2-3) – While the situation we are designing for is fairly unique,
      the final system should be expandable so that it is usable as universally as possible. The
      multi-seat system currently installed has four seats, but could be expanded to eight on the
      same hardware. Furthermore, if a motherboard with more PCI slots was chosen the
      system could possibly allow more than eight simultaneous users. The antenna will be
      designed for a five mile hop so that it is usable in a multitude of situations.




                                               6
Conceptual Designs
     Multi-seat computing system:
       There are a variety of options for the multi-seat computing system; one of the leading
        items of debate is the choice of operating system. Candidates thus far are Ubuntu
        Linux (used by the Fall 2008 team), Open Solaris, and Red Hat Linux. Initial testing
        of Open Solaris showed that it was not as user friendly as needed for a system of this
        nature. In an effort to maintain consistency the Spring 2009 group has again chosen
        Ubuntu Linux as the candidate operating system. This choice ensures that the
        environment will be intuitive and easily usable by young children. Also, this allows
        for the continued use of the Multi-seat Display Manager (MDM) which may not be
        usable in a non-Debian based operating system. Although less of a concern than those
        previously mentioned, the use of Ubuntu makes the system easier to set up for an
        administrator or anyone else responsible for maintenance.
       A secondary design decision is regarding the hardware used in our proposed design
        solution. Doing some rough estimation using data compiled by the previous
        semester's team the cost to implement a thin-client based computing system would be
        too high to justify switching to it over the current design. Although such a system
        would be highly scalable, the cost per seat is significantly higher due to the thin client
        hardware itself and the cost of a powerful central server to process the data. Again,
        the Spring 2009 team has chosen to move forward using the same hardware as the
        previous semester. The Lenovo ThinkStation S10 is a powerful workstation PC that
        more than suits the needs of our target user, and gives us a lot of processing power to
        run the multi-seat system. We have opted to use two S10 workstations minimally
        running four seats each for Manyara Secondary School. This should help with
        stability concerns, but at the same time allows for expansion up to a total of sixteen
        seats. On site administration will hopefully be easier since each PC will be less
        complex to set up.




     Antenna:


                                               7
       The primary decision regarding the point to point link antenna is whether to buy a
        commercially available one or to construct our own. A directional antenna designed
        for the 2.4GHz band that could achieve our target distance of two miles would cost
        upwards of $50. The advertised gain of such an antenna was generally around 20
        dBi, but sometimes up to 25 dBi (the higher the gain the more costly the antenna).
        There is no guarantee that a commercially bought antenna could actually reliably
        transmit a signal that distance, and buying such an antenna would make it
        unmodifiable (e.g. to make it more rugged to inclement weather).
       Preliminary research regarding constructing our own antenna led us to a “Do It
        Yourself” antenna constructed from an aluminum can. The can acts as a waveguide
        feed, and would be directed into a parabolic dish to achieve even more gain. A
        prototype dish could be constructed from thick gauge copper wire and aluminum
        window screen for low cost, however the final design would need to be considerably
        more sturdy for it to be deployed. Concerns over the sturdiness of this antenna led us
        to seek advice from various antenna experts. The antenna prototype we are in the
        process of constructing is a combination Yagi-Quad array constructed from the
        handle of a hockey stick and other readily available parts. This design makes the
        antenna more compact than a pure Yagi or Quad, and is anecdotally quoted at a range
        considerably higher than our target (10 miles). Another attractive feature of the Yagi-
        Quad combination is that it is easier to achieve impedance matching with the router
        which will allow for increased gain. Also, Yagi-Quad arrays generally provide better
        gain than patch or parabolic dish antennas. Once our prototype has been properly
        tested we will construct a version that can withstand adverse weather conditions.


   Uninterruptible Power Supply (UPS):
     Again, one of the major decisions regarding this aspect of our project is whether to
       purchase a UPS that is commercially available or to construct our own. Analysis of
       the components required to construct our own UPS roughly price it at about $900
       ($400 for a deep cycle gel-cell battery, $300 for a DC to AC inverter, and $200 for a
       gel-cell DC charger). This would create a UPS with an uptime slightly longer than
       our target. However, this design does not take into account an interface to the
       computer to let the users know how much time is left until the battery is dead. Also,
       this design does not take into account the wide variation in voltage from the wall
       outlets on the power grid (180VAC-240VAC), which could cause damage or at least
       reduce the life of the gel-cell DC charger). Since high reliability and low cost are
       important factors, this design is most likely out of the scope of this semester's project.
     Our other option is to purchase a commercially available UPS from a reputable
       vendor. Such a system will be designed to handle extreme variation in input power,
       and will also be able to interface directly with our computer system to notify the users
       when they should shut the system down. Using a proven system will ensure that the
       system can be shut down properly without losing data, and more importantly will
       protect the hardware from an improper shut down. One current candidate UPS (built
       by APC Power Systems) can provide around twenty minutes of uptime using our
       proposed computer system, and costs around $500. We feel that although this stock
       solution does not achieve the desired uptime, in terms of both cost and overall system



                                              8
       lifespan this is a better option. There is a strong possibility that we could create a
       battery bank to be hooked into this UPS, thus expanding the available charge capacity
       significantly.


   Router: The router will be a simple wireless device obtainable at any retail electronics
    store. By flashing the firmware of this device with Open WRT we can greatly increase
    the amount of administrative options that are available for the router to create a secure
    and reliable networking base for our computing systems. Setting up the router in this
    manner will allow us to install a filter and whitelist to control the content available to the
    school children. We can also control the route of the network traffic so that it is only sent
    to the appropriate destination, which as the network expands will greatly increase
    efficiency. The router hardware being used is the Linksys WRT54G v8 home wireless
    router which costs about $40. Low cost and proven compatibility with Open WRT are
    the leading factors in this decision. Content filtering and traffic control will be achieved
    using the Squid Caching proxy freely available for Open WRT. Our routers will be
    retrofitted with custom made antennas to allow for an expandable network in even the
    most remote of locations. By creating such an inter-networking scheme a single Internet
    connection can be shared amongst multiple schools to help reduce costs even further.




                                              9
Ranking of Conceptual Design
Computer System:
        Criteria            Thin Client Based Multi-seat System              Two Server Multi-Seat
                                 System       with 8 Monitors                with 4 Monitors Each

                                Lenovo
                                                           Lenovo
                            ThinkStation S1
                                                       ThinkStation S1
                             Server: $1200
                                                        Server with 4
                                                       Graphics Cards:   Lenovo ThinkStation S1
                             Lenovo L197
                                                            $1300        Server with 4 Graphics
                                LCD
                                                                             Cards: $1300
                             Monitor: $239
                                                        Lenovo L197
                                 each
                                                           LCD                Lenovo L197 LCD
       Low Cost
                                                        Monitor: $239         Monitor: $239 each
      (Priority: 4)         Keyboard/Mouse:
                                                            each
                                $30 each
                                                                             Keyboard/Mouse: $30
                                                   Keyboard/Mouse:                  each
                                Diskless
                                                       $30 each
                            Workstation Thin
                                                                              Cost per Seat: ~$594
                            Client: $285 each
                                                        Cost per Seat:
                                                           ~$431
                             Cost per Seat:
                                ~$704
                                                   Possible to expand
                              System is quite
                                                       this system to
                            expandable, but at
                                                      contain up to 8     Use half as many seats on
                            a higher cost. May
                                                    seats. Could use a        each server, allows
Expandability/Flexibility     need to upgrade
                                                      more powerful       system to be expanded in
    (Priority: 2-3)          the central server
                                                   server to get more the future. Slightly more
                               (costly) if too
                                                   seats than this, still           costly.
                              many clients are
                                                      lowest overall
                                 connected.
                                                            cost.
                                                    Centralized point           Two points of
                                                     of configuration,     configuration; however,
                               Performing            however, also a         they are mirrored so
   Low Maintenance
                            maintenance may           single point of        complexity stays the
      (Stability)
                            be difficult on the     failure. If system      same. Even if one PC
    (Priority: 3-4)
                               thin client.          goes down there      goes down there will still
                                                         will be no        be 4 (or possibly more)
                                                         computers.           seats available for


Antenna:
      Criteria              Commercially               Parabolic Dish with       Yagi-Quad Array


                                                  10
                               Purchased            "Cantenna" Feed
                          Cost per Antenna:
                          ~$60, could be more       Cost per Antenna:         Cost per Antenna:
                           dependent on gain                 $15                      $20
                           (need to do further        (made from an            (made from some
                         testing). Also need to    aluminum coffee can         base material (i.e.
     Low Cost
                        include cost for cables    available from most       hockey stick handle),
    (Priority: 4)
                          to run to the router,     stores, thick gauge       copper wire for the
                                should be            copper wire, and         Quad elements, and
                           approximately the        aluminum window           threaded rod for the
                        same for each antenna         screen scraps)            Yagi elements)
                                 (~$15)
                                                                             The gain for such an
                                                                                 antenna if well
                              Unsure if a          Unsure if gain will be          designed is
                          commercially built        high enough for our      anecdotally quoted at
   Expandability         antenna will provide        needs. Could have        a range well beyond
   (Priority: 2-3)      us with enough gain to          issues with           our requirement (10
                         properly transmit our      constructing a well       miles). This should
                                signal.              designed antenna.        provide for a highly
                                                                             expandable point-to-
                                                                             point mesh network.
                                                       Initial prototype
                                                   materials would most
                                                         certainly not       Initial prototype
                          Materials used to
                                                        withstand the        should be fairly
                        build the antenna may
                                                   elements in Tanzania.   ruggedly designed.
                         not be sufficient for
                                                   A more rugged design May have to do some
 Low Maintenance             the climate in
                                                   would be possible, but minor treatment of the
 (Rugged Design)        Tanzania. May not be
                                                     the cost would rise   materials to protect
  (Priority: 3-4)       able to easily modify
                                                    significantly. Also,      them from the
                         without messing up
                                                   we would likely have     climate. Compact
                                antenna
                                                        to completely     footprint should also
                            characteristics.
                                                      redesign the final     help this design.
                                                    product in terms of
                                                   impedance matching.




Uninterruptible Power Supply:
                                  Commercially Purchased
          Criteria                                                          Self-Built UPS
                                          UPS
                                   APC UPS Cost: ~$500                 Battery Cost: ~$500
         Low Cost
        (Priority: 4)             Additional Battery Cost:           DC-to-AC Inverter Cost:
                                           $150                              $300


                                              11
                                                                     DC Charger Cost (AC
                                                                         Input): $300

                                                                    Cost could vary dependent
                                                                   upon the power needs for a
                                                                    particular application (e.g.
                                                                   might need a more powerful
                                                                   inverter for a higher overall
                                                                         wattage system)
                                    The stock UPS supports
                                 approximately 20 minutes of
                                                                The self-built UPS would give
                                   uptime using our current
                                                                       a high amount of
                                   electronic configuration.
                                                                    expandability. The only
        Expandability            However, this UPS supports
                                                                   requirement would be to
        (Priority: 2-3)          the installation of additional
                                                                 ensure that the DC charger is
                                 batteries to increase uptime.
                                                                 powerful enough to properly
                                  This feature should help us
                                                                    charge the battery bank.
                                    meet our desired uptime
                                           requirement.
                                  Using a proven design will
                                                                  The self-built UPS gives no
                               ensure that the UPS functions
                                                                 guarantee that it will properly
                                  properly. One of the more
                                                                   handle the varying input
                                     important features is an
                                                                  power from the grid (could
                                interface directly to the PC to
                                                                cause damage to the system or
                                        inform users of the
      Low Maintenance                                             at least lower its lifespan).
                               approximate amount of power
       (Priority: 3-4)                                            Also, there is no built in PC
                                   left. This will give ample
                                                                 interface, so one would have
                                   warning for when to shut
                                                                to be designed. Failure of this
                               down the system to avoid data
                                                                   component could lead to
                                    loss and help protect the
                                                                damage to the hardware (both
                                   hardware from improper
                                                                  UPS and computer system).
                                            shutdown.
                               The commercially bought UPS
                                 is already in an enclosure so
                                 that the electric components       A self-built UPS would
            Safety
                               are not in plain view. This will require a proper enclosure to
        (Priority: 3-4)
                                   increase the safety of the   ensure that it is safely isolated.
                                      system in case anyone
                                      attempts to modify it.


Proposed Design Solution:
      Given the above conceptual designs, and our understanding of the system requirements,
Team 2 has selected an overall design to move forward with. The basis will be a similar
computer system used by the previous semester's team. There will be two ThinkStation S10


                                             12
workstations powering four seats each in the Manyara Secondary School. Each of these
workstations will run Ubuntu Linux, and will be configured into a multi-seat system using the
Multi-seat Display Manager (MDM). By using two workstations with only four seats each the
system will be expandable if desired, and possibly more stable. Four additional seats will be
added to the system currently installed in the Baraka Primary School.
        The satellite Internet link currently installed in the Baraka Primary School will be moved
to the Secondary School so that it can be on the power grid. In turn, a wireless link will be
created between the two schools using cheap, off-the-shelf wireless routers with modified
antennas so that a single Internet connection can be shared. The routers selected are the Linksys
WRT54G v8 routers and will be "flashed" with an Open Source firmware so that their
administrative capabilities are expanded. The firmware used will be OpenWRT, and will allow
us to put the Squid Caching proxy directly on the router to help control available content. A
whitelist will be implemented on the router, and will be accessible from any of the terminals
using a simple SSH connection (Administrators only). Also, we will be able to more tightly
control network traffic thereby making the network more efficient (forward packets only to their
actual destination). The antenna design will consist of a combination Yagi-Quad directional
antenna to achieve both the gain and impedance required to efficiently transmit our signal.
Range estimates thus far indicate that a wireless link could extend well beyond our two mile
target; however more testing is required to get an accurate maximum distance.
        All of the above will be connected to a properly sized Uninterruptible Power Supply
(UPS) to handle both fluctuating input voltage (from the power grid), and complete power loss.
The UPS chosen from American Power Conversion (APC) is estimated to provide about twenty
minutes of uptime off the shelf, but can be expanded using additional batteries. Our goal is to
allow our computer system to remain active for one hour in the event of complete power failure.
The diagram below illustrates our proposed overall solution.




                                                13
Project Management Plan

Personnel                                     Tasks
Daniel Newport            Installing operating system
(webmaster)                   o Set up multi-seat
                          Program installation
Kevin Bishop              Programming router
(Presentation/Lab)            o Install Filtering Software
                          Program installation
Steven Sadler             Designing / building antenna
(Documentation)           Selecting UPS
Brian Holt                Designing / building antenna
(Management)              Selecting UPS
Shared Projects           Selecting Routers, video cards

Components                      Resources              Source
Quagi Antenna            Hockey stick              ECE shop
                         Welding rod
                         Nuts and bolts
                         Coaxial cable
                         Connector
UPS                  VR 1500i                       APS
2 Computers          Think Station S10              Lenovo
Filtering Routers    Wireless G router              Linksys
Secondary            Wireless G router              Linksys
Routers
 8 screens           L157                           Lenovo
4 Video Cards        GeForce 8400 GS                NVIDIA
Operating system     Ubuntu Linux                   Free open source
Filtering Router     Open WRT                       Free open source
software
Secondary router     Open WRT                       Free open source




                                        14
Costs (Approximate)
Computer:
Lenovo Thinkstation S10 - $1190
Video Card - $64
Keyboard/Mouse - $30
Lenovo Monitor - $239
Router - $50
Antenna - $70 dollar per if bought
Antenna - $20 if built
UPS - $550

Software:
Ubuntu- $0
Multi-seat Display Manager- $0
Xephyr- $0
X windows- $0

All Software is open source




                                     15
Fast Diagram




References

Images

All images on the cover sheet of this document were obtained from Wikipedia.

All other images were created using Microsoft Visio.




                                              16

				
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