Alexander Chang

BlueTorrent: Cooperative Content Sharing for Bluetooth Users

People wish to enjoy their everyday lives in various ways, among which entertainment plays a major role. In order to improve lifestyle with more ready access to entertainment content, we propose BlueTorrent, a P2P file sharing application based on ubiquitous Blue tooth-enabled devices such as PDAs, cellphones and smart phones. Using BlueTorrent, people can share audio/video contents as they move about shopping malls, airports, subway stations etc. BlueTorrent poses new challenges caused by limited bandwidth, short communications range, mobile users and variable population density. A key ingredient is efficient peer discovery. This paper approaches the problem by analyzing the Bluetooth periodic inquiry mode and by finding the optimum inquiry/connection time settings. At the application layer, the BlueTorrent index/block dissemination protocol is then designed and analyzed. The entire system is integrated and implemented both in simulation and in an experimental testbed. Simulation and measurement results are used to evaluate and validate the performance of BlueTorrent in content sharing scenarios

P2P Content Distribution to Mobile Bluetooth Users

The use of handheld devices, such as smart phones for personal entertainment, has become commonplace in todays lifestyle. Virtually all of these devices are equipped with Bluetooth technology, which can be used to distribute entertainment content, such as music and movie clips. Mobile users can download content from opportunistically available infrastructure (e.g., digital billboards) and direct peer-to-peer (P2P) collaboration, which significantly increases content availability/coverage. P2P content distribution protocol design is heavily influenced by the characteristics of Bluetooth, which is a main departure from Internet-based content distribution. However, little has been done to understand the performance of overall Bluetooth operations, ranging from peer discovery to data downloading, in dynamic environments with mobility, interference, and different Bluetooth versions/chipsets. In this paper, we perform an extensive measurement study and find that Bluetooth-based content distribution suffers from time/energy-consuming resource discovery and limited bandwidth, even with the enhanced features of the latest Bluetooth version. Given this, we discuss strategies that can effectively improve the performance of the resource-discovery and downloading phases.

Comparisons of ZigBee Personal Area Network (PAN) Interconnection Methods

ZigBees low power consumption, built-in security method and ratified specifications make it very suitable to be used with medical sensor devices. Medical sensors in a human body self organize in a ZigBee Personal Area Network (PAN). At a higher level, these PANs are interconnected in a Healthnet. To this end, a ZigBee PAN detects the existence of another PAN with beacon detection or active channel scan and selects proper target based on the peak energy (when energy detection channel scan is used). Different ZigBee interconnection schemes are then possible. PAN bridge method uses special bridge node that works for different PANs with time division method. PAN merge method changes PAN coordinators role as bridge node and merges two PANs. Peer-to-peer network can be used when all PANs use the same channel and operates as an ad-hoc network. In this paper, we perform extensive evaluations using NS-2 simulations to compare PAN interconnection methods. Results show that the PAN bridge is the most useful method because it is not affected by router/node ratio and is applicable to different channel and user scenarios.

Opportunistic medical monitoring using bluetooth P2P networks

Remote medical monitoring with medical sensors and wireless communications has recently gained attention for the potential savings and improved quality in patient health-care. Currently, many mobile wireless medical infrastructures connect to the Internet in a point-to-point fashion, such as the cellular network. However, our research investigates new models for remote patient care that exploit P2P networking among patients and healthcare providers (nurses, doctors, emergency personnel). In this paper, we identify several medical applications based on P2P health networking focusing on two specific scenarios where nurses and patients are both equipped with Bluetooth devices. Nurses opportunistically collect, share and upload data in a P2P fashion. During an emergency, the nearest nurse is alerted via Bluetooth enhanced inquiry response mechanism. The simulation and test-bed experimentation demonstrate that Bluetooth P2P networking is both feasible and cost-effective in remote medical monitoring.

New bluetooth interconnection methods: Overlaid Bluetooth Piconets (OBP) and Temporary Scatternets (TS)

In a large scale Bluetooth network, the permanent Scatternet is regarded as the only method to interconnect Piconets. But, many Bluetooth devices do not support Scatternet. When they support it, features are limited. Moreover, in high mobility situations, the permanent Scatternet is not useful because of the extremely high overhead caused by frequent disconnections and reconnections. We propose Overlaid Bluetooth Piconets (OBP) and Temporary Scatternets (TS) to interconnect Piconets and form a virtual Scatternet. In OBP, every Piconet continuously changes its stages and collects metadata from Piconets within communication range. If metadata shows the existence of useful data to transfer, an inter-piconet connection is made and data is transferred. TS can be used instead of using permanent Scatternet to interconnect Piconets when needed. TS does not require large Scatternet formations and complex maintenance schemes. Moreover, it does not keep routing information. In this paper, we introduce and illustrate the OBP and TS concepts. We then compare throughput and efficiency of OBP and TS with respect to Scatternet.

Peer to peer video streaming in Bluetooth overlays

As Bluetooth is available in most personal and portable terminals (eg, cellular phone, PDA, videocamera, laptop, etc) Peer-to-peer video streaming through Bluetooth networks is now a reality. Camera equipped Bluetooth phones capture video and broadcast it to other Bluetooth devices and to the infrastructure. Tra ditionally, large scale Bluetooth networks were designed using scatternet concepts. However, many Bluetooth devices do not support Scatternet connections and, even if they support it, they provide only very limited features suitable mostly for static environments. In high mobility situations, a traditional Scatternet design is not useful because of frequent disconnections and reconnections. To overcome these problems, we propose overlaid Bluetooth Piconets (OBP) and simplified overlaid Bluetooth Piconets (SOBP) that interconnect Piconets forming virtual Scatternets. In OBP, every Piconet dynamically reconfigures to collect metadata from neighboring Piconets. If metadata shows the existence of useful data to transfer, an inter-Piconet connection is made to carry out the transfer. SOBP can be used instead of OBP once neighbor Piconets have already discovered each other. In this paper, we compare via analysis and simulation the throughput and efficiency of OBP, SOBP and Scatternet for video applications. We demonstrate the feasibility of video over OBP and SOBP for a representative application.

Comparison of Bluetooth Interconnection Methods using BlueProbe

Many Bluetooth researches are targeted to form efficient scatternets. However, scatternets do not have much popularity in general because many Bluetooth devices do not support scatternet capabilities and high mobility makes it difficult to keep the connectivity. Instead we choose temporary interconnection of piconets to reduce scatternet formation overhead. To compare several interconnection methods, we propose BlueProbe. BlueProbe finds out the allocated time slots size, which makes it apt for Bluetooth style TDMA capacity measurement. BlueProbe is applicable to both piconet and scatternet whether a cross traffic exists or not. Results based on our real testbed measurements show that the interconnection method is more important than the hop length and the number of simultaneous flows, whereas previous researches based on simulations concentrate on these two factors. Based on these results, we show efficient interconnection methods among Bluetooth Piconets.

Performance comparison of overlaid bluetooth piconets (OBP) and bluetooth scatternet

In a large scale Bluetooth network, scatternet is regarded as the only interconnection method among piconets. But, most Bluetooth devices do not support scatternet connection. Moreover, in high mobility situations, scatternet is not useful because of frequent disconnections and reconnections. We propose overlaid Bluetooth piconets (OBP) to interconnect piconets and form a virtual scatternet. Every piconet continuously changes its stages and collects metadata of piconets in the communication range. If metadata shows existence of data to transfer, an inter-piconet connection is made and data is transferred. We compared throughput and efficiency of OBP with those of scatternet. Results show the feasibility of OBP usage instead of scatternet

Temporary Interconnection of ZigBee Personal Area Network (PAN)

ZigBee is popular for Wireless Sensor Network (WSN) devices because of its low power consumption, built-in security method and ratified specifications. With these features, it is also suitable to be used with medical sensor devices. Medical sensors in a human body self organize a ZigBee Personal Area Network (PAN). These PANs are interconnected and form a HealthNet. For the interconnection, a ZigBee PAN detects existence of another PAN with beacon detection or active channel scan. Different ZigBee interconnection schemes are used after detection. PAN bridge method uses special bridge node that works for different PANs with time division method. PAN merge method temporarily changes PAN coordinators role as bridge node and merges two PANs. Peer-to-peer network temporarily share all resources when two PANs are met, but all PANs have to use the same channel and operate as an ad-hoc network. In this paper, we perform extensive evaluations using NS-2 simulations to compare PAN interconnection methods. Results show that the PAN bridge is the most useful method because it is not affected by router/node ratio and is applicable to different channel usages.

Video streaming over overlaid bluetooth piconets (OBP)

In a large scale Bluetooth network, scatternet has been regarded as the only interconnection method among piconets. But, most Bluetooth devices do not support scatternet connection. Moreover, in high mobility situations, scatternet is not useful because of frequent disconnections and reconnections. Overlaid Bluetooth Piconets (OBP) interconnects piconets and forms a virtual scatternet. This demo shows the possibility of using OBP instead of Scatternet for Video Streaming.