- Radio Signal Propogation and Processing
- Radio Network Management and Systems Innovations
- Radio Modem Innovations
- Energy Improvement in Radio Processing
Ambnet is a low-cost, self-healing, self-organized resilient broadband wireless network for multimedia streaming operating in WiFi bands.
WiFi networks have achieved major penetration in both domestic and enterprise markets throughout the world. They constitute the largely dominant method of broadband wireless access and, unlike their cellular counterparts, have established 802.11 technologies as a true global standard. The sheer volume of WiFi products has ensured that chipsets are available at commodity prices.
However, WiFi networks suffer from major drawbacks: 1- their limited range due to the transmit power restriction in unlicensed bands; 2- the random access, shared medium nature of the MAC layer which tends to collapse at high traffic loads (more than 30% offered traffic); 3- coverage area gaps due to walls, obstacles, limited range and the lack of rigorous planning at deployment; 4- unpredictable interference in unlicensed bands.
To be able to support multiple wireless synchronized streams of music to different zones of a house or building, Californian equipment maker Sonos designed SonosNet, a proprietary mesh network protocol exploiting the WiFi physical layer, where the mesh aspect is exploited to achieve extended range.
In a similar spirit, AmbNet is a next generation self-organized, resilient and self-healing multimedia streaming wireless network technology built on top of WiFi physical layer chipsets and capable of co-existing with multiple overlayed conventional WiFi networks. In AmbNet, a distinction is made between infrastructure devices (access points) and client devices (information sources or sinks), although an access point can also simultaneously act as a client device in some cases. Access points are AmbNet specific devices which can be modular in nature and incorporate multiple WiFi ports (to address more than one WiFi frequency channel simultaneously). Client devices can be AmbNet specific, or can be conventional WiFi-equipped devices (such as an iPod, smartphone or other) running AmbNet software.
To address range, coverage, and interference, AmbNet leverages a proprietary mesh network technology which incorporates macrodiversity. The latter feature is a combination of synchronous (multiple access points receiver or transmit the same packet simultaneously on the same channel) and asynchronous diversity (multiple routes through the mesh). Unlike conventional WiFi, the focus of AmbNet is session-oriented, and more specifically on constant bit rate (CBR) and variable bit rate (VBR) connections, implementing traffic classes and ensuring a degree of quality of service in uncertain environments.
The goal is to realize network technology which allows rapid ad hoc deployment, yet provides resilient, reliable operation in the presence of overlayed networks and access point failure, yet is capable of sustaining multiple simultaneous delay-sensitive high-bandwidth streams, such as HD video or videoconferencing.
AmbNet implements a contention-free protocol, such as in 802.11\'s point coordination function (PCF) or 802.16e\'s hybrid coordination function controlled channel access (HCCA). However, unlike those existing techniques, channel access (as well as macrodiversity management) is not centralized, but achieved through engineered emergent behavior. Proven minimalist multi-agent techniques developed in our lab will be levaraged to allow the access points to coordinate among themselves with minimal control signaling. By simply observing traffic and performing occasional handshakes with clients, access points are able to infer decisions taken by neighbors as well as ascertain the state of external interference (from e.g. overlayed networks), leading to implicit global organization. Such agents are used for channel / time slot assignment (and thus interference management), macrodiversity connection management, and power control. The system is intrinsically self-organizing and self-healing, continuously reevaluates channel assignment to avoid external and self-interference, and exploits macrodiversity for robustness, range extension, and elimination of coverage gaps.
I am a Full Professor at the Dept. of Electrical and Computer Engineering of Université Laval specializing in wireless communications and hardware implementations of communications and signal processing algorithms. For the last 7 years, I have worked in collaboration with Philippe Leroux (who was first my PhD student, now postdoctoral researcher) on self-organized network techniques and we now feel that we have reached a stage where these concepts can be applied effectively to a real-world problem. I also have extensive research, consulting and technology transfer experience related to WiFi. I led the development of a $1M prototype of an advanced WiFi access point for hostile industrial environments which embodied extensive RF and signal processing innovations. It also required redesigning the 802.11 PHY / MAC layers from scratch within an FPGA to support deep embedding of an antenna array.