Performance Analysis on Air-Conditioner Control CSMA/CD Protocol by Embedded Microcontroller UART Collision Detection

Abstract

This paper proposes a new CSMA/CD MAC protocol for air-conditioner control networks using only the UART built in a microcontroller as a collision detection mechanism. For performance evaluation of the proposed protocol, steady state throughput and average delay are calculated by analysis based on an imbedded Markov chain model. The analysis forecasts adequate throughput and delay for an example control network. The implementation of the proposed protocol to a very low-cost microcontroller that is installed in each air-conditioner consumed only about 1 kbytes of ROM and 20 bytes of RAM. The experiments on the performance confirmed the analysis results and obtained satisfactory throughput and average delay.

Analysis on burst packet buffering of communication gateway between fast IP network and slow facility fieldbus

“…shows a concept of combination of BMS and building facility networks, such as smart grid demand response control system for building facilities. A typical fieldbus for such facilities has design restrictions as follows : First, with regard to network cabling, mandatory conditions are low‐cost twisted‐pair cables and a transmission length of 1 km without repeaters. Therefore, the bit rate of these fieldbuses has to be as low as a few tens of kbps.…”

Analysis of Collided Signal Waveform on the Long Transmission Line of UART-CSMA/CD Control Network

“…Here, an important point is that each of v (1) HL (0, t) and v (2) LH (0, t) is distorted by the terminal reflections. Consequently, the waveform of the collision is not a simple superposition of logical levels with the propagation delay, but it becomes a complicated aggregation of distorted waveforms.…”

“…The values of cable parameters were measured as L 0 = 0.59 mH/km and C 0 = 0.12 µF/km resulting in the characteristic line impedance Figure 3 shows an example of numerical calculation of collided signal waveform v C (0, t) using our analytical Equations (2), (3), and (6) with the above-mentioned parameters. The original waveforms of sending and receiving signals, v (1) HL (0, t) and v (2) LH (0, t), are also superimposed on the same figure. The distortions due to the terminal reflections appear at the leading edge of each bit pulse.…”

“…Theoretical average throughput S(σ) of the UART-CSMA/CD protocol is given by the following expression for an offered load of σ, where σ is the number of signal-sending-trials per discrete time unit τ for each node [1,7],…”

“…UART-CSMA/CD (Universal Asynchronous Receiver Transmitter-Carrier Sense Multiple Access with Collision Detection) is a type of communication protocol for building facility control networks [1]. This protocol is based on detection of signal collision that is simultaneous transmission from more than two network nodes.…”