QoS SUPPORT FOR REAL-TIME HOME AUTOMATION NETWORKS ...

QoS SUPPORT FOR REAL-TIME HOME AUTOMATION NETWORKS MANAGEMENT VIA HIGH-SPEED INTERNET CONNECTION E. Topalis, L. Mandalos, S. Koubias, G. Papadopoulos Applied Electronics Laboratory, Department of Electrical & Computer Engineering, University of Patras Campus of Rion, 265 00 Patras, Greece

ABSTRACT This paper presents a novel architecture for Home Automation Networks management through high speed Internet connections ensuring QoS support. These connections can be ADSL links, an emerging technology which provides the user of the local loop with broadband speeds. So, a remote end-user who manages a Home Automation Network can use an ADSL connection to assure the real-time transmission of images, video, signals, etc. Since ADSL is a technology in the local loop, the presence of a signalling mechanism based on RSVP is necessary to maintain the high speed links through the network.

1. INTRODUCTION This paper presents a novel architecture for Home Automation Networks management through fast Internet connections. These connections can be ADSL links, an emerging technology which provides the user of the local loop with broadband speeds. So, a remote end-user who manages a Home Automation Network can use an ADSL connection to assure the real-time transmission of images, video, signals, etc. Since ADSL is a technology in the local loop, the presence of a signalling mechanism based on RSVP is necessary to maintain the high speed links through the network. A Home Automation Network (HAN) [8,9], [13,14] is a network that consists of home nodes. These nodes are devices, capable of using the communication resources provided by HAN in order to provide services to the user. These home nodes can be simple, like on-off switches, dimmers, temperature sensors etc, or more complex, like home security controller, energy manager, cameras, etc. Expanding power and influence of the Internet, together with the mobile device technology, high speed connections and advanced software, are creating a vast array of Web-based services. As HAN meet noticeable development and spread over the last years, the need for model that will support numerous such networks as well as Internet [10], mobile connectivity, high speed connectivity, and between the home under control and the user–side, comes into sight. Moreover, in order to support advanced HAN management (e.g. high-level telemedicine application focused on the real-time remote monitoring and control of the status of critical biomedical equipment) through Internet the need for high-speed connection and Quality of Service (QoS) arises. The simple V.90 connection at 56 Kbps is not adequate for HAN management in that case that cameras and multimedia devices are present in HAN. Asymmetric Digital Subscriber Line (ADSL) solves the problem of low speed connections that is presented in the local loop

between the network provider and the end user [4]. ADSL uses the most common mean of transmission (twisted pair of coper) achieving high rates of transmission (till 8 Mbps downstream / 1 Mbps upstream). Furthermore, ADSL is a low-cost solution and very easily integrated to the customer premises. ADSL technology gives the possibility of achievement broadband speeds in users of Internet networks. In the same time it combines low cost and reliability so that it is useful in multimedia applications. Depending on the requirements of the application, ADSL provides different speeds and quality of service that is characterized by a specific set of parameters, which are specified by the end user. The problem that appears is that the high speeds are guaranteed only in the local loop (last mile), while the WAN (Internet) is a best-effort network. A solution to this problem is the use of Resources Reservation Protocol, known as RSVP [1]. With this protocol the network guarantees the requested bandwidth, delay and percentage of lost packets for an application (flow). RSVP signals a set of parameters that determine the type of QoS [7] that is offered depending on the requirements of the application. Consequently, an ADSL connection can use a RSVP mechanism to request and assure a given set of traffic and QoS parameters end-to-end.

2. HAN TECHNOLOGY Today, an increasingly wide range of electrical and electronic products contributes to the comfort and savings in homes, by controllin g white goods, brown devices, telecommunication systems, heating and air-condition systems, lighting systems, security and safety systems. These home automation systems provide an increasing number of functions of growing complexity, while at the same time open up the possibility to develop entirely new applications. However, the integration of these systems requires that the various home appliances to cooperate automatically without human intervention. Therefore, in order to make HAN a practical reality, the standardisation of the involved communications and interworking aspects, is required. A great effort is undertaken both in US and EU for the development of standards for home automation systems. Some of the efforts led to proprietary solutions, however, most of them are joint efforts of leading industries and associations aiming to develop open and widely-accepted standards, which will bring the costs down and trigger the market. Basic characteristics should be offered by such a standard are the plug-and-play compatibility, simple installation, distributed control, multiple applications, future-oriented. It is evident that, the more flexible a HAN is the better services it offers. However, in order to co-

ordinate and integrate these services, an efficient HAN network management scheme is required.

3. ADSL TECHNOLOGY In ADSL a multiplexing of digital information with a channel of voice is giving the possibility in the customers of maintaining the voice service while simultaneously have access in the digital services of ADSL. This is achieved by frequency multiplexing between upstream channel, downstream channel and voice.

Voice

Downstream

Upstream

POTS/ISDN

Up to 8Mbps

UBR

specified n/a n/a

specified n/a n/a

specified specified specified

unspecified unspecified unspecified

unspecified

unspecified

Table 1. ADSL classes of service. ADSL

16 - 1024 kbps

Figure 1. ADSL channels. Upstream varies from usually 16 to 1024 Kbps, while downstream can be up to 8 Mbps. These features depends on the line quality and distance between end user and DSLAM (Digital Subscriber Line Access Multiplexer). ADSL can be over POTS or ISDN and all the data is transferred over the 2wire twisted pair traditional media. DSLAM collects all the ADSL connections in the local

loop, splits the voice from data and forwards the data to the ATM switch. ADSL users use a splitter to separate voice from data and an ADSL modem (or an ADSL router for a HAN). ADSL modem provides commonly Ethernet, ATM or USB interface to the end-user to connect his PC (LAN). Figure 2. ADSL connections, equipment, services Most ADSL manufactures offers mainly Constant Bit Rate (CBR) and Unspecified Bit Rate (UBR) services [5,6]. These services are the same as in ATM and are specified by a set of parameters listed in the next table (Table 1).

Attribute

CBR Traffic Parameters: PCR and CDTV SCR, MBS, CDTV MCR QoS Parameters: peak-to-peak CDV Maximum CTD CLR Other Attributes: Feedback

Class of Service

4. RSVP MECHANISM FOR QoS SUPPORT RSVP is a signaling protocol which was drawn and materialised by constructors of routers (eg. Cisco) for the engagement of resources in the nodes of Internet. It uses definitions of parameters as the Guaranteed QoS and Controlled Load. RSVP is used by a station so that it asks guaranteed quality of service from the network for a concrete flow of packets for an application. The support of applications with RSVP, assumes that

there are sufficient resources available, all over the transmission path (flow). Such flow of data is recognized by the combination of address of destination IP, type of protocol transmission (IP, protocol ID), and the port address of destination (DestAddress, ProtocolId, DstPort). RSVP functions over protocols IPv4 or IPv6 [2,3]. RSVP can either offer services of controlled load or services of guaranteed quality of service (Guaranteed QoS). The service of controlled load cannot guarantee upper limits of delay, but it commits capacity per application. We can say that this service resembles with the best effort service (UBR). The service of guaranteed quality of service assures a guaranteed level of capacity, for each flow of packets of an application, so that exists an upper limit in the delay. Contrary to the previous service, this

resembles the Constant Bit Rate service (CBR). RSVP signals through the PATH message (caller-sender) and RESV message (receiver) a set of parameters. These parameters are shown in the next table (Table 2).

HAN, as well as the handling of such information remotely by means of an Internet connection. The information is gathered either on request by the management device or on event reporting by the managed devices.

Tspec parameters Rspec parameters p : peak rate of flow (bytes/sec) R: bandwidth (bytes/sec) b : bucket depth (bytes) S : slack term (ms) r : token bucket rate (bytes/sec) m : minimum policed unit (bytes) M : maximum datagram size (bytes)

Management services over TCP and WAP technology are proposed, using a flexible architecture so that a multitude of home networks protocols can be accommodated even simultaneously.

Table 2. RSVP signaled parameters.

5. PROPOSED ARCHITECTURE 5.1 General Architecture This paragraph depicts the outline of the proposed architecture, especially in terms of Internet connectivity and QoS signaling. The HAN is connected to the Internet with a HAN Gateway, as well as the end-user (client). This Gateway, which is described in the next paragraph, can be a PC connected to the ADSL modem through a USB or Ethernet interface. When the remote user wants to establish a connection with the HAN in order to manage the devices within the HAN, RSVP is used for the allocation of resources in all hops in the network. So, the client sends a PATH message, which mainly contains the TSpec, with all the traffic and QoS parameters requested. Every RSVP -enabled router forwards this PATH message to the HAN gateway. The gateway issues a RESV message and every router allocate the requested resources. Two types of services can be obtained (CBR and UBR). Due to the fact that HAN gateway’s upstream is matched to the client’s downstream, ADSL is practically used as symmetrical connection in 1 Mbps maximum.

Figure 3. Proposed Architecture: HAN gateway with ADSL connection and RSVP

Figure 4. Reference Model. Moreover, the gathered information is diffused to the Internet through a HAN-to-TCP/WAP gateway, which provides the interlinking of the control and the mobile internet network. This gateway has been implemented in software and is hosted in the standard Windows platform. HTML/WML files are created, running in a WEB/WAP server. The proposed system and gateway have been integrated in a prototype system based on the EHS [13,14] network. Graphical interfaces for the manipulation of the home systems devices are also available in personal computers/mobile phones. The relevant reference model is illustrated in Figure 4. As described in [11], the proposed management system consists of the following elements: the communication protocol, the management service element and the management application services. In particular, the proposed architecture provides management network services on the basis of object collections.

Next step is to distinguish the parameters that determine in the two cases the speed and the QoS of the flow. There are two cases of RSVP mapping, depending on the type of ADSL service requested by the client: Guaranteed for ADSL-CBR or Controlled Load for ADSL-UBR service. The mapping mechanism will be presented latter.

5.2 HAN Managemet Network management [10] is the process of controlling a complex data network so as to maximise its efficiency and proper operation. Depending on the capabilities of the network management system, the management process supports the control and monitoring of the network operation. Until now, implementation of a HAN interface system was performed using an architecture specific for the needs of the protocol upon which the HAN is based. The used model is based on an architecture, which is presented in [11]. This model will allow the integration and co – existence, if necessary, of various HAN technologies, internet, the mobile world and high speed connections. The main objective of the proposed system is the collection of control - monitoring information and management [12] of a

Figure 5. Architecture Model.

Methods, properties, and events are specified for each object collection.

the very low-level interface is dependent on the system particularities. The proposed services and a short description are presented in the following table (Table 3).

Service

Description

HS_READ_STATUS

Take the network status. Its node sends the status to the manager. This status is a collection of node's properties (such as type, serial number, name and other). Read the network links. It's node sends, with which other node is connected, to the manager. Change the physical address of a node. We select the node by his physical address. Change the physical address of a node. We select the node by his serial number.

HS_READ_NETWOR K_LINKS HS_CHANGE_PHYSI CAL_ADDRESS HS_CHANGE_PHYSI CAL_ADDRESS_VIA_ SERIAL_NUMBER HS_READ_APPLICAT ION_PROGRAM

Figure 6. Architecture. The methods are used to invoke the services on objects. The protocol's design consists of new service primitives and the related service parameters as well as a protocol machine based on an object-oriented manipulation of the HAN devices. In addition, a management database contains constant information for each HAN device, which is periodically or on demand updated by new information on home variables.

Figure 5 illustrates the proposed architectural model, as extensively described in [11]. As shown, HAN consists of a number of HAN managed devices that serve various sensing/actuating elements and communicate each other by means of a medium bus. The management device connected physically to the same medium acts as the primary member of such a “control/management” domain. In contrast to the distributed feature of networking functionality of these networks, management is centralized “around” the management device. Furthermore, extra networking intelligence has been added to the management device so as to support interworking with a remote machine via an IP connection. As a result, control and monitoring is achieved both locally and remotely. All services are oriented towards the control, management, and reconfiguration or maintenance of a HAN. Therefore, a variety of services have been implemented to support the proposed management protocol which fully described in [11]. For instance, services such as Get-value(s), Set-value(s) and Value(s) Event Reporting are full supported in the proposed HAN management protocol. Moreover, the proposed system being an Application Service Element is fully compatible with the emerging “Konnex” (earlier “Convergence”) [15,16] notation and functionality. On the basis of this, the protocol machine is fully generic, adheres to an object-oriented approach, and only at

HS_READ_PHYSICAL _EXTERNAL_INTERF ACE & HS_GROUP_READ_P HYSICAL_EXTERNA L_INTERFACE HS_CHANGE_PHYSI CAL_EXTERNAL_INT ERFACE HS_CHANGE_PHYSI CAL_EXTERNAL_INT ERFACE_ VIA _SERIAL_NUMBER HS_GET_DATA HS_SET_DATA HS_EVENT -REPORT

HS_CHECK_NODE HS_RESET_NODE HS_ADD_GROUP_AD RESS HS_REMOVE_GROUP _ADRESS HS_PERFOMANCE_S TATISTICS HS_READ_MEMORY HS_WRITE_MEMORY

Read the application program that it's running in a specific node, or by a group command to read the application program that it's running in each node. Take information about the external devices that are connected to a specific node, or by a group command to have information about the external devices that are connected to each node. Change the external devices that are connected to a specific node. Change the external devices that are connected to a specific node. We select the node by his serial number. Read a data parameter of a specific node. Change a data parameter in a specific node. A node can inform, report to the manager something important, for example the change of a critical value Check if a specific node is working ok, or if it is still on the network. Reset a specific node. Add a specific node to hear in a specific network address. Remove a specific node from hearing in a specific network address. Take some network statistics and possible errors for a specific period of time for a HAN. Read a particular part of a node's memory in a specific node. Write in a particular part of a node's memory in a specific node.

Table 3. Proposed Management Services.

5.3 ADSL-RSVP mapping For the combination of ADSL technology with RSVP protocol a mapping algorithm has been developed. This mechanism maps ADSL parameters to RSVP parameters in order to pass the client needs to the network (RSVP capable routers) and the HAN gateway. This mapping is described in general terms in the next table (Table 4).

?f ADSL-Client-request = CBR (PCR up, PCR down, CDVT up/down, max CTD, peah-to-peak CDVup/down, CLRup/down) Begin (ADSL-parameter mapping to RSVP -parameter) Set RSVP integrated service = Guaranteed r_ upstream = PCR upstream p_ upstream = r_upstream r_downstream = PCR downsteam p_downstream = r_downstream b = r * CDVT / n |*b = token bucket depth, n = number of rodes*| ADSpec_ service class = 1 ADSpec _delay = max CTD M = 48 bytes m = 48 bytes End Else If ADSL-User-request = UBR Then Read ADSL-parameters (PCR up, PCR down) Begin (ADSL-parameter mapping to RSVP -parameter) Set RSVP integrated service = Controlled Load p_upstream = PCR upstream p_downstream = PCR downstream ADSpec _ service class = 0 ADSpec _delay = not assigned M = 48 bytes m = 48 bytes End Constract RSVP Message (Tspec, ADSpec) |*Traffic Specification (TSpec) profiles the data flow to be sent*| |*Additional Specification (ADSpec) contains information (service delay, bandwidth estimates, etc) generated by the data source on any or all network nodes in the downstream path*|

Table 4. ADSL classes of service. The above table describes the mapping for CBR and UBR services which are widely used. For services such rt -VBR, nrtVBR and ABR the mechanism must be moderated respectively.

6. CONCLUSION This paper discusses a proposed architecture for HAN management through fast Internet connections, like ADSL lines. In order to support advanced HAN management (like high-level telemedicine application focused on the real-time remote monitoring and control of the status of critical biomedical equipment ) through Internet, an architecture is proposed by using high-speed connection and ensuring Quality of Service (QoS). The proposed architecture guarantees QoS for a HAN management by using RSVP technology.

7. ACKNOWLEDGMENT The authors would like to thank Mr. Ion Beratis for his contribution to the ADSL to RSVP parameters mapping.

8. REFERENCES [1] http://www.cisco.com, White Paper -Resource Reservation Protocol (RSVP). [2] R. Rajan et al, “A Policy Framework for Integrated and Differentiated Services in the Internet,” IEEE ? etwork Mag., Vol. 13, No. 5, pp. 36-41, September/October 1999. [3] A. Neogi, T. Chiueh and P. Stirpe “Performance Analysis of an RSVP-Capable Router,” IEEE ? etwork Mag., Vol. 13, No. 5, pp. 56-63, September/October 1999.

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