Innovative use of building reinforced steel bars to transmit signals within a building

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Innovative use of building reinforced steel bars to transmit signals within a building


Author: Chan, Kam-tong Jason
Title: Innovative use of building reinforced steel bars to transmit signals within a building
Degree: Eng.D.
Year: 2009
Subject: Hong Kong Polytechnic University -- Dissertations.
Reinforcing bars -- Electric properties.
Electric conductivity.
Data transmission systems.
Intelligent buildings.
Department: Dept. of Electronic and Information Engineering
Pages: 200 leaves : ill. (some col.) ; 30 cm.
Language: English
InnoPac Record:
Abstract: Intelligent building, smart home, home networkings are hot topics in building industry. All these systems rely on a physical layer to transmit signal. Wire and wireless physical layer are commonly used. However, both layers have their limitations and associated problems especially in old buildings. In more than 20 year old public rental housing in HK, there is usually no spare cable containment for future cabling. Concrete chasing to install new cable containment in public corridor and tenant area is unavoidable for wiring new network cables. In view of higher cost and great nuisance to the tenant during concrete chasing, an innovative use of building reinforced steel bars to transmit signals and data was researched on the feasibility for future application. The principle of signal transmission in reinforced steel bars is similar as signal coupling in a transformer by means of magnetic flux coupling. Signals are transmitted as magnetic flux by means of a transceiver coil, which is pre-installed through reinforced steel bar and cast-in the concrete. The magnetic flux shall flow through all around the reinforced steel bars framework of the entire building. Another transceiver coil acting as receiver is also pre-installed in a remote area to couple the magnetic flux and transform the signals from the transmission coil. From the experiments in laboratory and two construction buildings, I proved that the building reinforced steel bars framework is feasible as a physical data transmission medium. Signals injected into reinforced steel bars can be received in remote area of the entire building in acceptable performance. The experiment results observed that the environment of reinforced steel bar framework is varying in impedance, considerable higher noise and poor environment as powerline signal transmission. In this thesis, a proposed system architecture and application schematic of wiring are introduced. The proposed architecture of building reinforced steel bar signal transmission is similar technology as the HomePlug standard. OFDM (Orthogonal Frequency Division Multiplexing) technique is adopted, which uses simultaneous transmission of a large number of narrow band carriers to achieve a higher data transmission rate. A pair of reinforced steel bar adaptor was modified based on a commercial product of powerline transmission adaptors, which is using the technology of OFDM. Laboratory experiment of using the pair of reinforced steel bar adaptor and reinforced steel bar sample was conducted the internet connection test and data file transmission test. The results were successful with higher transmission rate up to 50.63Mbps. After the successful experiment in laboratory, a real building experiment was conducted to verify the feasibility of forming a small local network by using the reinforced steel bar framework as a physical layer. The same low-rise school block and the same transceiver coils were used to test the data transmission rate and compare it with the previous magnetic coupling measurement performance. The results of experiment showed that the building reinforced steel bar framework can act as a physical layer for network and the transmission rate between the 3/F to 7/F was variated from 35.09 Mbps to 21.25 Mbps. The variation of transmission rate depends on the construction workmanship of reinforces steel bar, number of turn of transceiver coil, noise generation and pick-up, location and distance between transceiver coils. At the end of the thesis, cost savings regarding the use of reinforced steel bars as physical layer for data transmission is discussed. As per estimation, the saving investment cost in new residential building in Year 2007 and 2008 is about HK$224 million and HK$247 million respectively. For the existing residential buildings without sufficient spare of cable containment for upgrading network, the total saving investment cost is even up to HK$15.2 billion for about 664,909 old flats in Hong Kong.

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