Study of a Home Automation Network Radio Variant: The Case of Télédomotis

This paper studies how the home automation standard Tilidomotis (in the process of standardization) has been adapted to radio medium. Afrer presenting the Tilidomotis standard and concept, the paper highlights the constraints and characteristics of the radio medium in the 433 MHz ISM band. A protocol stack fitting these constraints is then introduced. The main characteristics of the low layer specifications show the extent of the work involved in converting a wired solution to a wireless one. 1. The TCICdomotis network 1.1. The notion and the applications The Telkdomotis club, under the aegis of CNETFRANCE TELECOM [ 11, has defined an interface in the process of standardisation in France : UTE (U2WSC25) and Europe : CENELEC TC205WG5 [2], between telematic distant services and home automation devices. The solution described in the draft version (see figure 1) is made up of a telephone specialised end line called MTH (Module Tilicom. a I’Habitat in French, meaning Residential Telecommunication Gateway) which dispatches data over one or more local interfaces named ITD ( I n t e ~ a c e de Telecommunication Domotique in French, meaning home telecommunication interface). These ITDs can be seen as networks communicating directly with the home automation devices named ED (or indirectly by the means of a home automation network) via EDTs (Element Domotique Tilicommunicant in French, meaning Home Automation Appliance with Telecommunication Capability). This system, intended to be put in everybody’s home over the next few years, will make it easier to set up many home automation applications, both from a technical and economic point of view [3], typical applications include telemetering, smart anti-theft alarms, teleoperating and telemonidoring. Telemonitoring makes it possible to obtain information about parts of a distant home. An example is the remote surveillance of dependent people. These types of services are based on the France Telecom specialised offer AMERIS, which is particularly well suited to the reliable transmission of alarm messages [4][5]. Fig. 1 : The TClCdomotis network 1.2 Standard and functioning Currently, the standard fully defines the wired type of the ITD interface as an RS 485 bus, working in asynchronous transmission mode at 9600 Baud rate, and combined with a specific protocol stack. The use of the radio medium is also considered, ISM radio bands (Industrial, Scientific and Medical) is a possible choice because no licence is needed, but no specifications are precisely given in the draft ITD version at the present time. This paper presents the first contributions towards the specification of the “radio ITD’ option produced by the Reseaux et Protocofes Team of the LIMOS laboratory of Blaise Pascal University, member of the TClCdomotis club. Three levels of protocol are classically used in the ITD draft specifications : the physical layer (level 1) , the data link layer (level 2) and the network layer (level 3). The physical layer mostly concerns the RS485 bus and its specific connectors The data link layer has three main purposes : Packing data in frames: the inter-character time sets the limits of frames, each character of a frame is separated from its neighbours by less than 0.25 character time, and a delay higher than 1.5 character time is observed between two consecutive frames. containing an address and Cyclic Redundancy Code. Frames begin with a header a frame length, and end with a 526 0-7695-0722-0100 $10.00