Open Research Projects
Scholarships and Funding
Note to potential students: the following souces of funding are available for top applicants
Research Topics/Projects
Wireless Sensor Networks Powered by Ambient Energy Harvesting (WSN-HEAP)
contact: Prof Winston Seah .
Bulk of the research on wireless sensor networks assume that sensors rely on a limited power source like batteries, and aim to maximize the lifetime of the network through efficient energy usage. When the batteries run out, a wireless sensor network is essentially useless. The ideal wireless sensor network is one in which the sensors do not have to rely on any onboard energy source. The sensors harvest the energy from the environment to power up, initialize, take readings and transmit the data. Each sensor has only sufficient harvested energy to transmit the data once (if not more), and they must coordinate among themselves to relay the data to the sink. While this approach has alleviated the energy problem, it exacerbates the synchronization problem among sensors. Synchronizing packet transmissions is very important to minimize collisions among sensors which, in our case, can be critical as there is very limited energy available. Another is knowing the neighbourhood (or locality) so that a next-hop node can be found to forward a packet to. This project focuses on the following closely related issues:
- node synchronization (for medium access control)
- locality awareness (for data forwarding)
- energy-efficient data forwarding
- cognitive methods for sensor data processing, such as, fusion, aggregation, and optimization
- energy-efficient modulation and coding scheme
- reliability mechanisms
Energy Harvesting and Its Impact on Wireless Protocol Design for Body Area Networks in Healthcare
contact: Prof Winston Seah .
In healthcare, a number of tiny bio-sensor devices are deployed on the human body to monitor vital signs of human such as blood pressure, ECG, spO2, and movement activities. These sensors create a wireless body area network (WBAN) for transmission of sensed vital signs from the sensors to a dedicated sink. Primary batteries can have excessive weight and size that limit the lifespan and autonomy of electronic devices because of the need of replacement. This makes them unsuitable in systems with limited accessibility and the cost becomes prohibitive in wireless microsensor networks with a large quantity of powered devices. Long lifespan and small dimensions of the power source are particularly important and advantageous for wearable electronics and systems. These have stimulated worldwide research in the field of energy-harvesting devices. However, the field of energy-harvesting technologies in wearable computing is still a new area due to its specific challenges such as human safety, form factor limitations and wearability. Recent investigations have been carried out with the goal to design and develop miniaturized wearable power generators. For example, a micro thermoelectric generator can produce small, though usable power from temperature differences as low as 5 K, introducing the capability to power devices from body heat. Energy can also be captured by muscular activity so that the human body can be used as steady energy source.
When applying energy-harvesting technologies to body area networks, the energy capturing rates varying according to the energy-harvesting technologies. Furthermore, the energy of sensor nodes will be unevenly distributed throughout the body depending on the physical locations of the sensors. As wireless communications consume most of the energy of a sensor node as compared to other energy consumers such as sensing data acquisition and computing, the transmission capability of a sensor node depends on how much energy it is able to capture during its operation. In this research, two areas will be investigated: (1) the existing energy-harvesting technologies and the off-the-shelf products that may be suitable to be applied to body area networks. (2) the impact of the above technologies on the wireless protocol design, possibly through the study of energy states and distributions.
Students working on this project will also have the opportunity to do an internship at the Institute for Infocomm Research, Singapore, for a period of between 3 and 6 months.
Robust end-to-end Wireless Multihop Protocols for Harsh Environments
contact: Prof Winston Seah .
In wireless multihop networks, it is common for nodes to experience constantly fluctuating link quality due to node movement, interference from the physical environment, power limitation that require communications to be minimized in order to save power, etc. When nodes move or the physical environment around the nodes changes, links may break due to obstructions, fading, and other forms of interference. In order to conserve power, it is often better to withhold the data or shutdown the link until conditions recover before resuming communications again. This results in intermittent connectivity, and even network partitioning when there is no path between a pair of communicating nodes. Some examples of such intermittently connected networks include: a) sensor networks that operate with stringent physical and environmental constraints and scheduled to be turned off periodically to conserve resources; b) military ad hoc networks where nodes (e.g. troops, vehicles, aircraft) may move randomly, may be destroyed or need to stop transmitting in order to avoid being detected; c) underwater wireless networks deployed for offshore engineering applications where the underwater acoustic communications channel is subjected to spatial and temporal blackouts; and d) vehicular networks where nodes move at high velocities. Protocols for such networks must be able to establish stable routes and also adapt quickly to changes in the environment. Failing which, the applications must first be able to tolerate delays beyond conventional IP forwarding delays, giving rise to what is commonly referred to as delay tolerant networks (DTN). This project encompasses the following aspects:
- Study the fundamentals of routing for wireless networks and design algorithms that select the most stable (but not necessarily shortest) routes, preferably without affecting the existing routing fabric.
- Study the performance of known routing protocols in delay tolerant networks, and design schemes for DTNs to meet the performance requirements of realistic application scenarios.
Green Cognitive Wireless Networks - Algorithms, Protocols & Systems
contact: Prof Winston Seah .
Wireless communications is highly dependent on the availability of reliable energy sources to operate. In recent years, the immense amount of energy consumed by the wireless communications infrastructure and devices has become a critical issue. Despite the emergence of more energy efficient technologies, we remain tethered to energy sources. Portable energy sources like batteries need to be replaced and/or recharged, and also pose environmental risks. The promise of untethered freedom by wireless communications remains hampered by the energy source needed to drive it. With the increasing concerns about global warming and the urgent need to reduce energy usage, it is therefore inevitable that we need to find alternative and more sustainable ways to deploy and operate wireless communication systems and networks. Furthermore, with the ever changing environment, networks require cognitive capabilities to adapt and evolve.
This research aims to develop new wireless communications technologies that can operate from minimal amounts of energy harvested from the environment and/or for long durations without the need to replace the portable sources (batteries) thus minimizing environmental damage from human intervention during the process of energy supply or replenishment. Ideally, such wireless communications networks will operate without the need for any human intervention and remain sustainable for years to come. Some of the areas to be studied include:
- More efficient ways of harnessing and utilizing the ambient energy that is present in the environment to power wireless communications. Research on the development of energy harvesting technology is not studied here, but rather, the focus is on the design of algorithms and protocols that fully utilize the scarce amounts of harvested energy.
- New wireless networking technologies that reduce energy consumption and improve energy efficiency by minimizing, e.g. unnecessary periodic transmissions like beacons, persistent channel access techniques, data redundancy, etc.
- Applying environmentally friendly metrics for route discovery and selection in wireless communication networks.
- Cognitive methods that learn and evolve to adapt to dynamic environmental conditions and network traffic loads.
Communications Architecture for Network of Unmanned Autonomous Swarms (CANUAS)
contact: Prof Winston Seah .
The use of many small low-cost unmanned air/ground/underwater vehicles (UAV/UGV/UUV or collectively as UxV) working as a collective group is a viable approach for surveillance and detection of potential threats/obstacles in harsh environments, e.g. underground, underwater, disaster zones, and battlefields. Effective communication mechanisms in such groups of unmanned vehicles (UxVs) are a key requirement for their meaningful deployment. A fully distributed communications architecture is necessary for reliability and robustness, especially since the communications system needs to support both the transport of data among the UxVs, as well as, commands that influence the motion of the UxVs; the latter is very critical for ensuring that the group of UxVs maintain formation while performing their tasks, and the commands must reach their desired destinations (nodes) within the given time constraints, so that the targeted nodes have sufficient time to act on the command. An example scenario can be a UxV of the group straying away and nearest UxVs transmitting commands to direct it back towards the group. In this project, we focus on designing protocols that ensures high-priority messages like motion commands are given precedence to transmit over the wireless medium. Given the stringent time constraints, a time-scheduled mechanism appears to be a more viable approach. The aim of this project is to study the state-of-the-art in networking schemes for such harsh environments, and design a suitable scheme for swarm control and communications.
Game-/queueing-theoretic Approaches in Wireless Communications Systems
contact: Prof Winston Seah .
Traditional networks are built to cooperate based on a mandatory network communication semantic to achieve desirable qualities such as efficiency and scalability. With technological maturity and widespread technical know-how, a different set of network problems emerged - clever users try to alter network behavior in a way to benefit themselves at the expense of others. The problem is more pronounced in mobile ad hoc networks (MANET) where network ownership can be largely public. At one extreme is the malicious node that aims to disrupt the operation of the network. We focus instead on selfish, rational user misbehavior while keeping this danger in mind. In this project, pricing and promiscuous listening are avoided because of known technical feasibility in actual deployment scenarios. While adopting the punishment approach, we avoid network-wide punishment as it is an easy avenue for denial-of-service (DoS) attacks. Some approaches for study include:
- Model based on the work of Masaki Aoyagi's imperfect private monitoring for the dynamic Bertrand oligopoly, and fit it to wireless multi-hop networks. The model further relates the relevance of routing broadcasts and packet acknowledgments to network cooperation.
- Apply game theory to study the performance of bandwidth sharing in communal networks where each member of the network is expected to its fair share of network resources in order to gain access to other members' network resources, and most importantly, discourage unfair and selfish behaviours.
- Model the performance of wireless multihop networks for network and civil resource optimization and pricing. This can be applied to the realistic scenarios of networking resources that support intelligent transportation systems, emergency services, logistics, etc.
Exploiting Radio Irregularity in Wireless Sensor Networks
contact: Prof Winston Seah .
Wireless communications, which is an integral part of IoT, suffers from radio irregularity %u2013 a phenomenon referring to radio waves being selectively absorbed, reflected or scattered by objects in their paths, e.g., human bodies that comprises liquid, bone and flesh. Radio irregularity is often regarded as a problem in wireless communications but, with the envisioned pervasiveness of IoT, we aim to exploit radio irregularity as a means to detect the presence of people, animals and other objects. Applications for this technology, include motion/instrusion detection for security and surveillance, automated people counting, wildlife detection and tracking for determining absolute abundance or pest control, vehicular traffic monitoring, etc.
Network Congestion Control and QoS Provisioning
contact: Dr Qiang Fu .
As the network bandwidth increases, it seems congestion control may not be an issue in the future. This may be partially true. But, think about our highway systems. There are always occasions you can drive as fast as the speed limits allow; there are definitely occasions snails would smile at you. Apparently, we need a congestion control mechanism, which is highly adaptive.
Another issue is that the current congestion control mechanisms are designed for the wired networks. They are struggling with the features brought by mobile and wireless networks. These features include non-congestion triggered packet losses, delay variation and mobility.
A third issue is the greedy behaviours of network users. Have you ever set up multiple TCP flows for a given application, or have you ever modified TCP parameters making your TCP flows send data faster. This is essentially %u201Cstealing%u201D bandwidth from the competing network users. Unfortunately, the Internet is designed based on the end-to-end principle. It is very hard (if not impossible) to solve these problems under the end-to-end principle.
This project looks at addressing these issues from the perspectives of resilience, scalability, responsiveness, bandwidth utilisation and fairness in various environments.
Concurrent Data Transfer for P2P, Grid Computing, Content Distribution Networks and Others
contact: Dr Qiang Fu .
This project investigates the use of parallel data transmissions to improve network performance. The use of parallel data transmissions could be over the same path or multiple paths and between a single pair of sender / receiver or a set of senders / receivers. One scenario could be that you are sending data through both the Ethernet adapter and the wireless adapter at the same time. Another popular example is BitTorrent, a P2P application. In BitTorrent, multiple concurrent TCP flows are established between a set of senders/receivers over multiple paths. In Grid computing, concurrent TCP flows are used for intensive data transfer. This concept can also be used in Content Distribution Networks (CDNs) and bandwidth-limited wireless networks. There are also many other possible applications. For example, it can facilitate seamless handover in mobile networks, enhance information security, and improve transmission reliability.
Network Measurement for Protocol Design
contact: Dr Qiang Fu .
The Internet is getting faster and ubiquitous, and we have seen the integration of Internet core networks and wireless access networks. Unfortunately, the current Internet protocols were not designed for this. They perform poorly in wireless environments and cannot fully utilise the potential of the Internet - we need better network protocols. Understanding network traffic is fundamental to protocol design and evaluation. In this project, you will be measuring Internet traffic and establish the indication of the measurement results on protocol design and evaluation.
Cross Layer Design Using Software Defined Radio
contact: Dr Qiang Fu .
The layered network architecture has greatly helped the evolution of the Internet. But overtime, it has created isolation between solving lower-layer and higher-layer problems. The problems have become more complex and harder to solve in this kind of isolation. There is no doubt cross-layer coordination is the way to go.
This project investigates cross-layer coordination using software-defined radio (SDR). The traditional use of SDR is limited to the domain of physical layer. However, the current development in SDR has made it possible to adapt all the layers in the protocol stack. This presents unique challenges and opportunities for the design of cross-layer mechanisms.
IP Networks for Efficient Energy Generation, Consumption and Distribution
contact: Dr Qiang Fu .
%u201Cgreen%u201D has been a hot word for politicians. It is equally hot for academics. The Information and Communication Technology (ICT) consumes approximately 2% of the global energy consumption. Making an all-optical network would save energy because the routers do not need to maintain a packet queue. Making ICT devices more intelligent would save energy %u2013 when the users are not active, the device could switch to energy-saving mode. However, all the reduction is within the 2%. It is not much. How about use ICT to help other sectors save energy.
This project investigates the possible network architecture and protocol suite that enables intelligent scheduling of energy generation, consumption and distribution. For example, the network collects real-time energy demand and sends the information to the generator network, which adjusts its energy generation scheduling accordingly. In the opposite direction, the generation network may advise a community network, suggesting stop non-urgent energy consumption if possible. The community network may adjust its consumption behaviours accordingly. Another issue is how to distribute the energy from the generator network to the community network. There would be multiple distribution paths %u2013 it sounds like a routing problem.
Network Security in Wireless Sensor Networks
contact: Dr Qiang Fu .
This project investigates the attacks in Wireless Sensor Networks (WSN) and the security issues for data aggregation, routing, localization and key management.
Content networking over wireless mesh networks
contact: Dr Qiang Fu .
The traditional content distribution is based on client-server model. This architecture may work very well for the applications where clients download/request content (video clips or MP3) from a server in a random manner. However, for some applications such as IPTV where millions of clients may be watching the same high-definition TV program at the same time, the client-server model would require outrageous server bandwidth. This is because all the client requests have to be served by the same servers.
The Internet community has been looking at a few solutions such as IP multicast, multicast overlay networks, content distribution networks (CDN) and peer-to-peer distribution (P2P). In reality, some of these technologies have gained popularity, e.g., P2P by BitTorrent, CDN by Akamai. However, it is not clear how these technologies will evolve and be used in the future. On the other hand, new challenges are being introduced by the emerging wireless networks such as Wireless Mesh Networks (WMN). A WMN forms a local network through multiple wireless links. The content distribution and storage model in a WMN would be significantly different from the ones in the Internet. This is due to the constrains on media access control, delay variation and bit errors. This project investigates content storage and distribution over wireless mesh networks.
Localisation in Wireless Sensor Networks
contact: Dr Qiang Fu .
Have you used or heard about location-aware applications. When you are travelling around, your hand-held smart phone tells you what places of interest are nearby. It may even be able to make a schedule for you. This would help you fully enjoy the place you are visiting. The localisation in this scenario is not very difficult to achieve, because your smart phone has the assistance from the base stations or even GPS.
In wireless sensor networks, the issue is much more difficult to address. The sensors are low-power devices and intend to be low-cost. This requires hardware and software simplicity, preventing the use of sophisticated hardware or algorithms. Furthermore, the low-power transmission of sensors makes localisation vulnerable to noises. Given these difficulties, localisation is very valuable in sensor networks for the purposes such as routing, sensor deployment and retrieval and security management.
Data Dissemination Using Disruption-Tolerant Networks (DTNs)
contact: Dr Qiang Fu .
When we are sending data over the Internet through desktops, laptops or hand-held devices, we usually assume an end-to-end connectivity can be maintained. However, there are environments where it is difficult or impossible to maintain continuous end-to-end connectivity. Think about the following scenario. In an event of earthquake, network infrastructure is destroyed. A wireless mesh network is quickly deployed. However, we do not have enough network nodes for the required network coverage. We have to move the network nodes around so that a message can be delivered from A to B. If you are lucky, you may be able to maintain instantaneous end-to-end connectivity from A to B. If the routing protocol can establish a route quickly and the MAC protocol can give the bandwidth in time, a packet could be luckily delivered from A to B using an end-to-end approach. However, more likely it is difficult or impossible to maintain end-to-end connectivity. Or, the connectivity can not be maintained long enough for the protocols to act. In this case the end-to-end delivery is impossible. A store-and-forward approach has to be adopted. This project investigates the design issues of network architecture and protocols in disruption/delay tolerant environments.
Effective Spectrum Access in Heterogeneous Wireless Systems
contact: Dr Qiang Fu .
The popularity of wireless communications is driving up the demand on the availability of radio spectrum. Unfortunately, radio spectrum is by nature scarce and expensive. This emphasizes the efficient utilisation of radio spectrum.
However, in practice a large amount of radio spectrum is licensed to particular operators or users. Only licence holders can use the assigned spectrum. This, on one hand, facilitates spectrum management and Quality of Service. But, on the other hand, this also results in inefficient use of spectrum - even if the licensed users are not using the spectrum, it cannot be used by other users. The idea of giving unlicensed users the access to the licensed radio spectrum opens up an opportunity for efficient use of radio spectrum. However, the access has to be made transparent to the licensed users - the licensed users must not be affected when they need to use the spectrum. Unfortunately, this is not a trivial task. There are a few challenges. A user must be able to detect unused spectrum, and determine the spectrum that best suits the requirements of its applications. For instance, some of its applications may require low latency and some may require high throughput. The different requirements may result in selecting different spectrum. A user needs to support seamless mobility, because it is very likely the user has to use spectrum in a dynamic manner. Furthermore, there needs to be a mechanism that can fairly schedule spectrum between users and systems. The challenges are even more evident and real in practice, because of the coexistence of heterogeneous wireless communications systems. A user may have to jump between different systems to maintain or optimise its communication without harmful interference with other users. This project will be focused on formulating these challenges and providing working solutions.
Content Distribution for Vehicular Ad-Hoc Networks (VANETs)
contact: Dr Qiang Fu .
A VANET consists of a dynamic set of vehicles and roadside units. Each of the vehicles and the roadside units can be considered as a network node. A vehicle could have its own Local Area Network (LAN), e.g., a LAN in a train. A roadside unit could be a WiFi base station, a WiMAX base station, a satellite or even a sensor node. A VANET can be a vertical integration of heterogeneous networks. VANETs are considered an example of Mobile Ad-Hoc Networks (MANETs), but have distinct features. VANETs are not as unorganised as the general MANETs - the vehicles move within and along the roads. VANETs are not as infrastructure-less as MANETs, because of the roadside units. These features make VANETs appealing for applications.
Many applications can be developed using VANETs to enhance road safety and passenger comfort. For example, VANETs can be used to deliver short and critical safety messages, real-time multimedia applications or simply download a large amount of data. These applications have different performance requirements: low/high throughput, short/long latency or reliable/unreliable transmission. To accommodate the various performance requirements in such a dynamic and heterogeneous environment is a complex task. This project aims to address the architectural and protocol design principles in VANNETs.
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