Toshiba Laptop + Ubuntu, Wireless Switch Problem

Just a quick post, about an annoyance with my Toshiba Satellite laptop. Maybe it will help someone, but the wireless card had no power because the “hardware switch” was turned off. This laptop has no power switch. The function keys which turn it on/off in Windows do not seem to work in Ubuntu. The solution was found originally in the post below, but to save some time, the solution for me was to power the laptop off, take out batter for 30 seconds, holding down the power button. Then when the laptop is powered back on, the wireless in Ubuntu works. Hopefully this won’t need to be repeated over and over, but at least its working now.

Upcoming PhD QE Progress

So I’ve been doing my PhD for over two years now, and I haven’t posted a reflective “state of the thesis” post in quite some time, so here it is. I have maxed out my 50 pages (not included ToC and references) for some time now, it’s just been in the process of revision for the last month or so! I have more or less settled on what my research actually is now and am getting a clearer picture of it in my head all the time.

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 :P) 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…

Why Blanket Wireless Coverage in Waterloo Failed, and Potential Solutions

Today the KW Record ran an article entitled “Blanket Wi-Fi plans unplugged in Waterloo Region and Guelph, but growing in Stratford”. I thought I’d throw in my two cents since this issue is very related to some of my research. Overall to me, the biggest factor that contributed to the failure of blanket wireless access in the Region of Waterloo was the cost of the service for users. From what I remember, it was on part with many high speed Internet plans. Why would someone pay the same price to have potentially slower, less secure service than competing wired services?

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 :P)

BWCCA 2010 – Adaptive Mixed Bias Resource Allocation for Wireless Mesh Networks

Today I presented a recent paper on “Adaptive Mixed Bias Resource Allocation for Wireless Mesh Networks” at the BWCCA conference in Fukuoka Japan. The paper is authored by myself and Thabo Nkwe from the University of Guelph. The abstract is below:

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)

Research Day – Summer 2010

Tomorrow I present at Research Day at University of Guelph at 1:30pm. Here is the abstract for the presentation:

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