It turns out what should be a simple process is a bit tricky in Ubuntu. You would expect to be able to create an IP access point fairly easily so that you can share your Internet connection to other devices using Bluetooth. (It turns out it may be possible with Blueman – http://blog.larsstrand.org/2009/04/sharing-internet-connection-over.html, but I’ve never had any luck with setting it up this way.) Here’s some of the steps and resources I used to get it to work. I am using one laptop with a generic usb dongle and another toshiba netbook with built-in Bluetooth for this.

Before anything is started, you need to make sure the devices are paired and trusted with one another. I found the easiest way to get this to work is with blueman (it is in the Ubuntu repos). Also it seems to work better if you initiate the pairing from the client (the computer not sharing the connection).

First, you need a bridge interface. This is easy enough in Ubuntu, by editing the /etc/network/interfaces file. If the interface you wish to share is eth0 (if you want to share a Wi-Fi connection instead, you could switch this with something like wlan0 or whatever your Wi-Fi interface is), you could add something like this:

auto br1
iface br1 inet dhcp
  bridge_ports eth0
  bridge_fd 9
  bridge_hello 2
  bridge_maxage 12
  bridge_stp off

Next you need to make sure both computers can see each other via Bluetooth. This requires enabling scanning and turning the NAP into a master and the client(s) into slaves. This can be done as follows:

sudo hciconfig hci0 piscan

sudo hciconfig hci0 lm MASTER,ACCEPT

sudo hciconfig hci0 lm SLAVE,ACCEPT

You can now check to see if each of the computers can see each other on bluetooth by running:

hcitool scan

Next you want to start the NAP server on the computer you wish to share the connection from. (This is the computer with the bridge device). This script, which is available on the git repository will allow you to start up the NAP server. (it may also be possible to use pand, but I haven’t had any luck yet with it)
This script is called test-nap. It takes a single argument, which is the name of the bridge device. So in our case we would first need to chmod +x the file (to make it executable), then run it like this:

./test-nap br1

#!/usr/bin/python

import sys
import time
import dbus
from optparse import OptionParser, make_option

bus = dbus.SystemBus()

manager = dbus.Interface(bus.get_object("org.bluez", "/"),
            "org.bluez.Manager")

option_list = [
    make_option("-i", "--device", action="store",
        type="string", dest="dev_id"),
    ]
parser = OptionParser(option_list=option_list)

(options, args) = parser.parse_args()

if options.dev_id:
  adapter_path = manager.FindAdapter(options.dev_id)
else:
  adapter_path = manager.DefaultAdapter()

server = dbus.Interface(bus.get_object("org.bluez", adapter_path),
            "org.bluez.NetworkServer")

service = "nap"

if (len(args) < 1):
  bridge = "tether"
else:
  bridge = args[0]

server.Register(service, bridge)

print "Server for %s registered for %s" % (service, bridge)

print "Press CTRL-C to disconnect"

try:
  time.sleep(1000)
  print "Terminating connection"
except:
  pass

server.Unregister(service)

After this, you can search from the client to see if the NAP service can be discovered with the command:

sdptool search NAP

The last thing to do is edit the /etc/network/interfaces file on the client side (the device which will connect to the Internet via Bluetooth. When pand connects, it uses a bnep0 interface. You need to add the following to your file:

iface bnep0 inet dhcp

Now we are ready to connect. This is how you connect:

pand -c <mac address of your server BT device>
sudo ifup bnep0

Links:

• http://global.hkepc.com/forum/redirect.php?tid=1710030&goto=lastpost
• https://www.linux.com/learn/tutorials/346552-personal-area-networking-with-bluetooth
• http://ubuntuforums.org/showthread.php?t=1632825
• http://forum.doozan.com/read.php?2,2698
• http://xn--9bi.net/2009/06/17/tethering-iphone-3-0-to-ubuntu-9-04/

Officially the topic is “Radio Resource Management for Quality of Service in Heterogeneous Wireless Networks”. This is quite the mouthful, I know. Really what it boils down to is: Making various wireless technologies (Bluetooth, WiFi, WiMAX, 3G, 4G, … , etc) seamlessly work together. Many devices are capable of connecting to many of these radio access technologies (RATs), but often it is not seamless. What do I mean by this? Well suppose I am inside a university building, deep in the basement (where they tend to put CS students ) where there is no mobile reception (3G, 4G etc.). I start downloading a large file, or call someone via wifi. Now I want to walk to my car because it’s time to go home for the day. Many networks now are not able to handle this, and it is interrupted after you change networks. Furthermore, you often have to manually tell the device you want to leave one network and join another. Seamless means this should all happen without you noticing. This is the focus of my research.

The biggest problem that I am concerned with is called handoff or handover. This is when the switch between RATs occurs. Traditionally, this also occurs when a mobile device switches from one tower to another, and it usually involved predicting the motion of the device along with some other factors for Quality of Service (QoS). For a vertical handover, we may or may not need to predict motion. If the heterogeneous wireless network (HWN) is densely covered, many RATs are available throughout the coverage region (as opposed to a sparsely covered where a given location may have access to one technology at once). In a dense HWN, the problem becomes a multi-criteria question.

1. Which network is most economical for me to connect to?
2. Which configuration of (network, client) pairs is most profitable for the operator?
3. Which network is able to provide me with the required QoS?

More technical details to follow…

The Atria plan used large WiFi cells, with very expensive antennas (see the apartment building near University Plaza, which I believe was one of them).

Many other cities (much larger ones) have been very successful in providing blanket WiFi, using a completing different coverage model and cost model. The best example is San Francisco where a company named Meraki provides free wifi for over 100,000 people using their Mesh Router devices. These devices cost between $399 and $1500 each, which is still expensive, but likely much cheaper than anything used by Atria. These devices likely have much lower range and handle dense areas compared with the atria cells which seem to be designed for large areas, and require many people to subscribe to pay for their costs. The argument in the article that WiFi coverage in metropolitan areas is difficult seems like a terrible attitude to have for an area that has a reputation as a high tech leader. San Francisco likely has much greater challenges in this regard compared to our tiny city.

Example coverage map in San Francisco

Instead of using these expensive devices, much cheaper devices such as linksys wrt routers could be used. These routers support linux, and because of this much customization is possible such as mesh networking. While these devices are less reliable than the previous more expensive solutions, it may be a good way to at least get the network started cheaply. Additionally, areas which are not used by as many people could be covered with cheaper routers, while areas with more dense traffic may be covered by expensive ones.

The argument in the article that WiFi networks are unnecessary because of cellular networks is ludicrous! If that is the case, why are every smartphone and other device including WiFi radios in them? It’s because data on cellular networks is way to expensive. Any place where a device can get free or low cost WiFi should be used instead of the cellular network. One large problem with this at the moment, however is that it is not seamless to go from a cellular network to a wifi network. For example, it is often not possible to carry on a phone call while switching networks, or continue downloading or steaming without interruption. This will change with much of the research in heterogeneous networks.

One potential model that hasn’t been explored much is community wireless networks. In this case, devices could be provided to anyone willing to provide access to their own home network for the community. The incentive could be either donations from users, or a very small fee (2 – 5 dollars per month) which is distributed to providers. Additionally, anyone who provides a part of the network is able to get on free to other parts of the network. Of course, there’s nothing to stop the larger companies like Rogers and Bell from creating the same type of value added service. Since so many people already have wireless in their home using Rogers and Bell, they could create some type of login where you take your bandwidth quota with you and have access to anyone else’s network who is also participating. This way, you are not using their bandwidth cap (only their “speed” – which may introduce a whole other range of problems )

In May of 2010, I attended an IEEE conference called the International Communications Conference (ICC 2010) in Capetown, South Africa. This conference is considered the one of the top conferences by the IEEE communications society and is attended by many experts in the communications field. I found one of the keynote speeches by Dr. Steven D. Gray, Head & Vice President Corporate Research, Huawei Technologies to be especially relevant to the current debate in Canada over usage based billing (UBB). The keynote is available free online from the IEEE ComSoc (please note, the keynote I am referencing here starts at about 51 minutes in the presentation).

While the key point about profitability deals with wireless carriers, it may also be relevant to wired network providers. Especially in Canada for the following reasons:

1. The vast, sparse country which must be connected
2. The constant upgrades to equipment required
3. The limited capabilities of backbone and infrastructure networks & increasing speeds of user connections
4. Steady growth in traffic from users

1. The vast, sparse country which must be connected

Compared to other countries in the world, Canada is very sparse. According to a Wikipedia article surveying population density around the world, Canada places 228 in the world. According to this figure (from Gizmodo), Canada ranks 8th in the world for average broadband speeds. Compared with the USA, which ranks 15th (and has a population density almost 10 times higher than Canada), we have less than twice the average speed for roughly the double the cost. Considering our low density and similar geographic size, one would expect we would pay much more.

Map of the Internet [http://www.opte.org/maps/]

2. The constant upgrades to equipment required

The communications industry is constantly evolving as engineers and scientists figure out how to make faster connections or find new ways to communicate (for example, 10 mbps ethernet to 100 mbps to gigabit and beyond), (example 2: Ethernet to fibre optic, or even next generation wireless networks). Every time something new comes out or improvements are made, the companies must put money into making it work with what they already have, deploy new equipment and so forth. Often because the networks are becoming more complex it requires hiring more people to manage them (which may eventually be solved by autonomous networking, but that’s a different story).

Another example of expense to keep up to date in Canada is Bell Canada. Many people with Bell Internet also have wireless access points provided by Bell. Unfortunately, these access points default to (or in some cases only support) WEP encryption. This encryption is not secure at all and can be broken by your average teenager with instruction off youtube. However it could be argued in hindsight this type of expense is the company’s fault.

Furthermore, to increase capacity in the network, it is not as simple as just adding another link between an under-supplied area. Consider a small town where a few people make use of the majority of the connection cause poor performance for the others in the town. This town may be a candidate for increased capacity, but by adding another connection the company does not stand to gain any increase in subscribers and thus may stand to lose money. Now expand this example to larger cities where higher and higher proportions of the population are using more and more of their connection to the point where almost everyone is straining the infrastructure. There are solutions to this type of problem though. Some companies in the US and other places make use of traffic shaping (which while unpopular is a cheaper alternative to the user). Perhaps two types of plans could be put in place, one with traffic shaping and unlimited usage, or one with no traffic shaping and limited usage.

3. The limited capabilities of backbone and infrastructure networks & increasing speeds of user connections

One of the problems with the increased cost to the providers is the increased speed of user connections. Allowing users to have faster connections means they can request more information at once. Imagine many people flushing their toilets at the same time where the pipe at the road isnt big enough to handle all of the water at once. This is what has been allowed to happen. The problem is further compounded because it is not as simple as water simply flowing through pipes. At each junction, decisions must be made on the direction of the flow. If too much traffic arrives at once junction, the time it takes to make a decision is slower than the rate new traffic is appearing and big problems happen.

4. Steady growth in traffic from users

As can be seen in some of the figures in the ICC keynote, traffic from users is growing exponentially. Unfortunately, the service providers’ revenue is usually growing linearly, so there is eventually a point where it is not profitable for the companies to provide Internet service (assuming the cost to provide exponential traffic grows exponentially). This is the most compelling point for usage based-billing. Unless we can somehow find a way to reduce the growth of data, the only way to retain profitable ISPs is to increase the revenue.

Internet growth [Cisco]

5. Conflicting interests between user service and shareholders profits & the disconnect between what you get and what is advertised

This is another important problem with ISPs. Perhaps this is the reason that the infrastructure managed to get into its current state (where it cannot handle everyone making full use of their advertised connections). In order to gain a competitive advantage over competing ISPs, each company often advertises their maximum potential connection speeds. There is never any mention of the network past the point where your house connects to the ISP. Sure if no one else in your neighbourhood is using the connection you might get close to the advertised speed, but as many people know, you often don’t get close. From the shareholder point of view, you want the company to spend as little as possible on infrastructure. Perhaps it may be necessary the enforce a rule that companies must be able to provide the full advertised speed, regardless of how many other people are on the network. Of course, this would make the Internet much more expensive.

6. Potential Solutions instead of UBB

There are many promising technical solutions to some of the problems that are causing the gap between cost and revenue in Internet technologies, however many of them may not make enough of an impact, or are still too premature to cause a difference yet. So in the meantime something must be done.

In the case of providing video services or other multimedia streaming services such as Netflix, LastFM etc. technologies such as multi-casting may be used to deliver common data to a group of users with one packet (in the unicast model, one packet is sent over and over again for every user, even if they are watching the same content).

To reduce the cost of human maintenance and oversight over the networks, applying autonomic computing techniques to networks so that they can self-manage, self-protect etc. may be beneficial.

Exploiting peer-to-peer, caching and other technologies that reduce communications over the large distances on the Internet may help reduce the cost of delivering traffic on the Internet.

Providing tiered Internet service, where users pay for different service levels may be another model altogether that allows companies to remain competitive without usage based billing. Make traffic that causes high strain on the networks (such as streaming video, real-time traffic etc.) more expensive than traffic that is delay tolerant and has lower requirements (web, email etc.)

Perhaps the government itself should take a more active role in providing Internet infrastructure in Canada if the Internet is seen as another piece of infrastructure like roads, bridges and electricity.

Concluding remarks

Of course, there are many assumptions to the case for UBB. The assumption that the cost for service providers is growing exponentially is the biggest and most important. Wired network access doesn’t have the same problems wireless has (the broadcast, limited bandwidth medium, interference etc.) so the comparisons may not actually be valid. The case becomes complicated by the fact that many ISPs are also in the business of providing wireless service, media services (tv, radio, newspaper etc.) that causes conflicts of interest.

The trouble I have with charging the heaviest users is that everyone seems to be trending towards using more and more traffic. In my own experience with large ISPs I feel like I’m always getting less for more money (usage caps have been getting lower and lower, yet the bill keeps going up). The advertised speeds of the networks are going up, but the capacity seems to be falling since we can get more faster, but less overall.

Then in GUI select Modem->Connect
Then select “Bell Mobility” when prompted.

Abstract:
In wireless networks, conditions may change rapidly and unpredictably. Often wireless networks are not designed to adapt to these changing conditions and perform poorly when they become congested. The multi-hop broadcast nature of wireless mesh networks amplifies the problem of poor wireless performance. Mixed bias scheduling has previously been applied successfully to wireless mesh networks however, it still suffers from similar problems when conditions change rapidly. In this work we propose an adaptive mixed bias (AMB) algorithm which uses a tabu search approach to change based on delay and dropped packets in the network. The proposed scheduling approach consists of three important algorithms, namely, the tabu search algorithm, move generation, and utility function. The adaptive mixed bias approach is compared against IEEE 802.11 and the non-adaptive mixed bias approach. The performance is evaluated using the packet delivery ratio and average end-to-end delay metrics.

Here are the slides from the talk: BWCCA-NGWMN2010-final (pdf)
and here is the link to the pdf from the conference: Adaptive Mixed Bias Resource Allocation for Wireless Mesh Networks (pfd)

Title: Radio Resource Management in Heterogeneous Wireless Networks

Abstract: Wireless networks are quickly becoming pervasive allowing users to stay connected anytime
anywhere. However, current implementations are not seamless. There are many different radio
access technologies (RATs), for example 802.11 (Wifi), 802.15 (Bluetooth, Zigbee), 802.16 (WiMAX)
and 3g cellular / mobile technologies which are not inter-operable. The aim of heterogeneous
wireless networking is to bridge the technological gap between the existing equipment and software.
When this occurs, the wireless spectrum may be used more efficiently and it is expected users will
have a better experience using the networks. Ideally, the devices should be able to select the best
RAT at a given moment in time based on some criteria, for example cost or capacity. A background
on the architecture of heterogeneous networks will be presented. Problems such as handover, radio
resource management and quality of service (QoS) will be discussed and a direction for further
study will be established.

Update: Here are the slides from the presentation for those who are interested:Research Day 2010 (pdf) – Jason Ernst

While I don’t have a video for you to watch the entire presentation, I do have some pictures, and I’ll post the paper and slides I presented in case any one is interested. If you have any questions feel free to post on here or email me directly and I’ll be happy to answer any of them.

J.B. Ernst and M.K. Denko, “Cross-Layer Mixed Bias Scheduling for Wireless Mesh Networks,” in Proc. IEEE International Conference on Communications (ICC), Cape Town, South Africa, 2010.

Abstract—In this paper we propose a mixed bias approach which makes use of cross layer optimization. The cross-layer parameters are based on conditions in the network from multiple layers and are used to determine resource and time allocation for nodes in the network. Unlike existing proposals, we propose to bias against several parameters such as link quality and queue size in addition to node distance. We also propose a combined mixed bias approach which takes into account multiple parameters together. The scheme is evaluated using simulation experiments. The performance results are reported in this paper.

Download the paper (pdf)
Download the presentation slides (pdf)

The following instructions explain how to install the latest stable version of ns3 (as of April 14th, 2010 as of March 22nd 2011 with ns-3.10) on windows 7 with cygwin. It should work with newer releases as they come out, but if not leave me a message and I will update the instructions. I will try to include any common problems I have encountered, or those of users who comment on the post experience in order to make your install easier.

Step 1:
Download & install cygwin. (note: I install it in the recommended directory “{System Root}/cygwin/”). Make sure you select “install” for python and devel. This will ensure you have python and gcc/g++ as well as all of the dependencies. You can do this by clicking on the word default in the list of packages. I left all of the other package options on default for the install.

Step 2:
Download ns3.7.1Download the most recent version of ns3 from their website (you will likely want the all-in-one version if you are just starting out. Save the file to “{System Root}/cygwin/home/{your-username}”. Alternatively, you can try downloading the file directly within cygwin using something like “wget http://http://www.nsnam.org/releases/” where filename is the name of the release you wish to install.

Step 3:
Start cygwin. At the cygwin prompt type: “tar xvf ns-allinone-3.7.1.tar.bz2″ (or whatever the filename is depending on the version you downloaded). This will unpack the ns3 archive so you can use it.

Step 4:
After it has unpacked, change directory to the new ns3 directory with the following: “cd ns-allinone-3.7.1″. Then build ns3 by typing the following: “./build.py”. You can probably grab a coffee or tea while it compiles.

ns3 on windows 7 with cygwin

Step 5:
You should be good to go. You can validate the install by changing directory again to the ns-3.7.1 directory (“cd ns-3.7.1″) and running “./test.py”. It will let you know with a PASS / FAIL for each test case. You can now edit the files yourself. The scenario files are located in “” and the source files are located in “”. Good luck!

Note: For those getting remapping errors, I have finally had the same trouble. This is what worked for me: Open command prompt, change to your /cygwin/bin directory. Type: ‘ash’. Then type ‘/bin/rebaseall’. You can now try cygwin again and it may work. If it still does not work (this happened to me), you can apply this fix to the rebaseall script. (you can edit it using some tool like notepad within windows).