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 )

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)

Next is the price for these things. While they seem to be too expensive (monthly) to me, I am willing to pay it since I understand the costs of setting up a network in a country as spread as Canada. However if I try to tether a Blackberry or iPhone to my computer, all of the major carriers in Canada seem to add on extra costs which make it impractical. The other reason why I do like some of the blackberry models is for international use. For instance when I was in UK this past month, I couldn’t use my LG8100 phone at all. Some of the newer Blackberries supported by Rogers and Telus that I have looked at support many technologies and seem like they make work.

Anyways, this post has mostly been a rant, so feel free to leave your experiences or some suggestions on what I might do to try to get some solution to my needs. I have tried asking the sales staff at some of the places to help me out and they have been useless so far. But thats another story.

Update: I have decided on a Blackberry Storm 9530 since it supports international roaming and has many of the features I would like in a phone. It looks like I will just settle on buying a separate mobile stick for use with my laptop. I don’t want to have to worry about all of the hassle of getting the extra software & the questionable legality that is involved with trying to get data through my phone. So far I am quite happy with the phone, it is quite a step from my LG8100.

There were people from 40 different countries there and I feel like I met someone from almost every one of them at some point. There were over 300 people at AINA this year, which apparently is down from the last couple of years (where they had 4-500) but it was still a great conference for me. I will post my slides from my presentation in this post in case anyone is interested, along with a link to the paper once it is available. I submitted another paper last night for a conference in Toronto and am working on two more papers, so hopefully I’ll be travelling soon. I am trying to aim for ICC in South Africa next year.

Here are a few pictures from the conference.

Abstract:
This paper addresses the problem of scheduling in Wireless Mesh Networks (WMNs). The paper first discusses existing scheduling algorithms and classifies them based on the technique they use and their implementation frameworks.Then detailed discussions of the proposed scheduling method are presented. Simulation experiments are conducted to compare the performance of fair scheduling with the method that does not use fair scheduling. The simulation results confirm that the proposed scheduling method has better performance with respect to the metrics used for performance evaluation.

J.B. Ernst, M.K. Denko, “Fair Scheduling with Multiple Gateways in Wireless Mesh Networks”, in Proc. of the 22nd IEEE Int. Conf. on Advanced Information Networking and Applications (AINA 2009), Bradford UK, 2009.

The paper itself is available through IEEE Xplore

Here are some pictures from the day:

Preparing for the Defense before Everyone Arrives

Some Members of Pervasive Computing and Wireless Network (PerWin) Research Group, University of Guelph

Answering Questions from the Committee at Guelph

After some relaxing, a conference in UK and some business related projects I will finally have some time (hopefully) to update the site with all the projects, articles and source I have been slowly working on the past few months in between working like crazy on my M.Sc. This fall I start my Ph.D. which will likely at least start from the work I just worked on.

As soon as I get the thesis completed though I hope to post alot more new content on the blog (as well as a potential redesign since this one seems a little cluttered and busy to me). Check back soon for alot more in-depth info on using ns3 since that is what I have been using for my thesis experiments lately. Update: I am set to defend on May 18th at Guelph. Let me know if you are interested in attending, I will provide more details via email.

In other news, the University of Guelph has officially accepted me to their Ph.D program to start in the Fall of this year (still under Dr. Denko) so I am pretty excited about having the opportunity to continue my research in Wireless Networks. I am still waiting on responses from a couple of other schools (Waterloo & Calgary) so if I end up getting accepted to either of those I will have quite a decision to make. Update: I have accepted a position at the University of Guelph and will be starting there in the fall of 2009.