WiMAX technology support for applications in environmental monitoring, fire prevention and

telemedicine

E. Guainella1, E. Borcoci2, M. Katz3, P. Neves4, M.Curado5, F. Andreotti6, E. Angori7 1University of Rome “La Sapienza” (I), 2University Politehnica of Bucharest (RO), 3 Technical Research Centre of Finland (FI),

4Portugal Telecom Inovaçao (PT), 5University of Coimbra (I),6Italtel (I), 7Datamat (I).

Abstract- IEEE 802.16/WiMAX is one of the most promising

technologies for Broadband Wireless Access, both for fixed and mobile use. Many application scenarios have been studied so far, including Wireless Local Loop, Wireless DSL and as an alternative to 3G in developing countries. This paper presents a WiMAX based end-to-end architecture and novel applications running on top of mobile WiMAX, to extend the European research network Geant 2. The scenarios include monitoring of impervious areas, fire prevention, tele-medicine and tele-hospitalization, all to be developed in the framework of the Europen project WEIRD.

I. INTRODUCTION

In the last few years wireless Metropolitan Area Networks (MANs) increased momentum, due to the need to reach more and more user communities – in case isolated – by overcoming the cost barriers of wired technologies. This trend paved the way to the standardization of IEEE 802.16 wireless interface, also knows as WiMAX, which incorporates the latest advancements in data link and physical layer technology.

In the meanwhile, most of the worldwide research initiatives started to focus on IP network architectures able to decouple vertically the Application Stratum from the underlying Transport Stratum. The main objective of these studies and developments is the seamless end-to-end integration of the various network technologies, and this is commonly achieved through special “convergence layers” that are able to enhance the network with QoS, mobility and security procedures.

This paper describes how the WEIRD (WiMAX Extension to Isolated Research Data networks) European Integrated Project [5] will contribute to the integration of WiMAX into next generation National Research and Education Networks (NRENs) and the European Gèant 2, trough the design, development and validation of advanced management and control plane functionalities able to support novel application scenarios, such as environmental monitoring, tele-medicine and fire prevention.

The paper is organized as follow: Section II describes the application scenarios driven by the research communities partner of the WEIRD consortium, Section III describes the overall system key technologies adopted by the project beyond the state of the art, Section IV describes the high level system architecture, Section V describers how results will be validated

within the four European test-beds, and finally Section VI draws the conclusions.

II. NOVEL APPLICATION SCENARIOS FOR WIMAX

As a broadband wireless access (BWA) technology, WiMAX is able to provide ubiquitous internet access allowing end users to be connected to the internet independently of their location. Additionally, it also contributes for decreasing the digital divide gap, by providing internet access to rural areas where the deployment of a wired access solution will not be economically feasible for the telecommunication operators. A set of scenarios in which the WiMAX technology plays a crucial role have been defined by the WEIRD consortium: Environmental Monitoring, Telemedicine and Fire Prevention.

A. Environmental Monitoring Environmental Monitoring is very important in impervious

areas such as seismic and volcanic zones. An effective and reliable monitoring system must be implemented to preview the occurrence of a natural catastrophe in these areas. To achieve this aim, permanent and mobile stations (video-cameras and sensors) are installed. The collected information from the stations is sent in real time to an aggregation point using Mobile WiMAX and then forwarded to the scientific community in the Monitoring Centre through a WiMAX backhaul. Furthermore, Mobile WiMAX is also used to allow real time communication between mobile users, which visit the impervious area, and the Monitoring Centre. A global and simple overview of the Environmental Monitoring Volcano scenario is shown in Figure 1.

Figure 1: Environmental Monitoring Volcano Scenario

It is required by this scenario that the Mobile WiMAX

technology is able to provide QoS aware real time services,

This work has been carried out in the framework of the IST WEIRD project, partially funded by the EU with the contract IST-034622-IP.

such as voice and video over IP communication. Moreover, fast mobility is also mandatory allowing users, as shown in Figure 1, to keep their connection to the Monitoring Centre while moving in the impervious area.

B. Fire Prevention Several pilot projects have shown how the use of

technologies such as sensors and video and infrared cameras can help fire detection. The main obstacles to the implementation of such systems are the costs and image quality related to GSM/GPRS communications and the difficulty to implement radio links to transmit video in mountainous regions. In the WEIRD project there are three applications for fire prevention that take advantages of the WiMAX technology. The first application is related to the transmission of jpg images and text data taken from the Forest Fire Simulation System located and operated in the District Civil Protection Coordination Centre (CC) to a mobile unit in the field (PDA/Laptop). The second application is related to fixed and mobile video surveillance. This application has three components:

1) Fixed video cameras transmitting video to the CC associated with meteorological parameters. Data is transmitted to a web server and is accessed in a web page where the user can also controls the movement of the cameras.

2) A mobile unit that works as a mobile watch tower. It transmits text data and video data to the CC.

3) Video transmission and voice communication between the helicopters of the fire fighter brigade and the CC. Helicopters can provide images from a new top-down perspective impossible to achieve without a mobile unit. This can be especially interesting as helicopters are highly mobile and can therefore be quickly ordered to different locations providing fast information updates under changing conditions, like a turning wind direction.

Figure 2: Mobile Video Surveillance Scenario

The third application intends to distribute a network of

sensors in the Urban-Wildland Interface, specifically in forest locations with hard accessibility, where ambient conditions can significantly vary. The environmental data collected by the sensors could include temperature, wind direction and humidity, as a complement to the images provided by the fixed video-cameras, helping not only the fire prevention but also to control the fire. The sensors will collect environment parameters and will transmit them to a sink node with less

memory and energy restrictions. The sink node will support an interconnection between sensor networks and existing IP based network infrastructures through the WiMAX technology.

Mobility support is crucial in these environments, requiring the implementation of fast handoff mechanisms and the provisioning of specific QoS levels in mobile environments.

C. Telemedicine E-health is one of the areas where WiMAX technologies can

substantially contribute to improve the daily activities and thus enhance the quality of life. Today a large number of activities are carried out with limited success, unnecessary costs and human difficulties because of the impossibility to exchange real time information between different elements of the chain that are not at fixed locations.

Remote Diagnosis is one of the possible cases where Mobile WiMAX plays an important role. For instance, a doctor is on duty on an ambulance and is called to intervene in a city street where a car accident occurred. The ambulance is equipped with a portable ultrasound device, connected to a notebook and to the hospital through a Mobile WiMAX channel. The doctor finds a laying man who might have internal injuries. To allow the fastest possible intervention, he charges the patient on the ambulance and, while going to the hospital, takes some images with the portable ultrasound and sends them via Mobile WiMAX to the hospital, where the surgery is being prepared. He also sets-up a videoconference session with the surgeon at the hospital to inform him about the patient health condition and discuss the treatment options. This scenario is illustrated in Figure 3.

Figure 3: Telemedicine (Remote Diagnosis) Scenario

Besides the Remote Diagnosis scenario, Mobile WiMAX is

also important for other Telemedicine applications such as Remote Follow-up, Remote Monitoring and Remote Assistance.

The Telemedicine scenario requires real time services and applications such as voice and video over IP in a mobility environment to support real time communication in case of emergency.

III. KEY TECHNOLOGIES

In order to support efficiently such applications, WEIRD consortium is investigating the adoption, among others, of the following key technologies and is designing its system architecture to integrate them:

- a flexible QoS and Resource Control and Management: WEIRD has designed it taking into consideration an abstract interface towards a virtual hardware, that is able to hide the complexity derived by the different manufacturer and the different IEEE 802.16 version (i.e. “d” or “e” version), in order to be as much as possible flexible in system integration thanks to the development of a proper adapter. At client side, a WEIRD agent and WEIRD Application Programming Interfaceses (APIs) will permit the provision of enhanced QoS and seamless mobility features to both legacy and IMS compliant applications.

- the use of IETF NSIS for QoS signaling [4]. The IETF

working group has proposed a new signaling protocol suite for the IP Control Plane, to manipulate the state along the data path, allowing two modes of signaling: path coupled and path decoupled. The NSIS solution is attractive because it offers significant enhancements comparative with RSVP traditional per flow signaling: separating signaling message transport from signaling applications; decoupling of discovery and transport of signaling messages; general support for signaling to hosts, networks and proxies; better support in mobile environment.

Architecturally, NSIS consists of two protocol layers: NSIS Transport Layer Protocol (NTLP), composed of a

specialized messaging layer, denoted GIST, to transport signaling application layer messages. The GIST runs over standard transport and security protocols (e.g. UDP, TCP, Stream Control Transmission Protocol (SCTP), and Datagram Congestion Control Protocol (DCCP).

NSIS Signaling Layer Protocols (NSLPs), each running signaling application-specific functionality, including formats and processing rules of messages to be exchanged between NSLP peers. A typical example is QoS NSLP for resource reservation signaling.

- the application of radio-over-fibre (RoF) techniques for

WiMAX signal distribution, within the access segment of the communications network, will be integrated. By using optical fibre for WiMAX signal distribution, the Access Service Network Provider may extend the coverage of its network by separating the costly control equipment at the central station (CS) / Point of Presence (PoP) from the TX/RX equipment,

i.e., the antenna, so called base station. The main benefits resulting from the use of RoF WiMAX signal distribution are the following: Low cost, through extremely simple base stations where only the laser and photo detector and electrical filters, amplifiers and the antenna are needed; Low attenuation through optical fibre transmission; Huge bandwidth, with compensation of chromatic dispersion; Low weight; Immunity to EMI; Multi-service and multi-operator capability (infrastructure coexistence), especially when considering WDM technology for optical transmission; Flexibility and capability for dynamic configuration of the network capacity. Thanks to the centralization of the intelligence of the network in the CS, the operator can distribute the traffic capacity of their network on a time basis depending on the specific requirements of their customers (sport events, fairs, day/night demand, etc.)

IV. SYSTEM ARCHITECTURE

Figure 4 illustrates the generic WEIRD infrastructure for a mobility context, simplified and abstracted in order to emphasize the interfaces between entities in the WiMAX Forum terminology, [1] .The generic interfaces between the entities are denoted by R1, R2,..R8. The overall system includes three parts: Customer Premises Equipment (CPE), Access Service Network (ASN) and Connectivity Service Network (CSN). The CPE may be composed by single user IEEE 802.16 Subscriber Stations or multiple users SSs in case that “behind” SS, LANS/WLANs with several users/hosts exist. Subscriber Stations can be fixed (SS) or mobile (MS), linked by air with Base Stations (BS). An ASN may control, and aggregate several BSs, based on a wireline or wireless IP infrastructure which in its turn is linked through an ASN Gateway (ASN-GW) to the CSN. The ASN-GW plays here both the gateway but also control role for ASN. In a mobile environment the CSN may be the Home CSN or Visited CSN respectively. Connectivity with other networks may be realized via IP backbone (e.g. GEANT 2). Application entities clients and /or servers can exist in the CPE side or in CSN networks.

From architectural point of view the WEIRD system has a

well defined scope within a general multi-plane end to end

ASN GW

ASN

R8

R6

R6

R1 802.16 SS/MS

802.16e BS

LAN/ WLAN CSN

(Visited) R3

R5

802.16e BS

802.16 SS/MS

CSN (Home)

IP Backbone

CPE

WEIRD specific scope Figure 4: WEIRD generic infrastructure

service and network architecture. The latter is vertically structured into two “macro-layers”, or “strata”, i.e., ‘Application and Service Macro-Layer/Stratum’ and ‘Transport Macro-Layer/Stratum’. Horizontally, the architecture is composed of Management (MPl), Control (CPl) and Transport/Data Plane (DPl). This approach follows the recent trends, which aims at decoupling the applications and services from transport technologies, in order to allow heterogeneity in the core and access network technologies [2], [3].

The Applications and Service Stratum includes the layers and functions performing management, control and also operations of data (e.g adaptation, transcoding, etc.) independently of network transport. Transport Macro-Layer/Stratum includes the layers and functions performing management, control for resources and traffic and also operations on data in order to transport the data traffic through various networking infrastructures.

The Management Plane performs generally - medium and long term management functions - related to service management at the Application and Service Layer macro-layer and resource and traffic management at Transport macro layer. It provides coordination between all the planes. The following functional areas identified in ITU-T Rec. M.3010 are performed in the MPl:FCAPS – Fault, Configuration, Accounting, Performance, Security management. Each architectural layer may have associated its own layer-manager; also a general management macro-layer may exist, to coordinate all layer managers.

The Control Plane (CPl) includes all layers which perform short term control actions related to: services and applications stratum- through signaling, the CPl sets up and releases connections, and may restore a connection in case of a failure; transport stratum - CPl performs the short term actions for resource and traffic engineering and control, including routing.

QoS NSLP

GIST

WEIRD API

MIP

RC Policies

TCP/UDP/SCTP/DCCP IP layer Security

IP

Convergence Layer

IEEE 802.16

QoS NSLP

GIST

MIP FA

RC Policies

QoS NSLP

GIST

SIP Proxy

MIP HA

RC

AAA

Policies

TCP/UDP/SCTP/DCCP IP layer Security

IP

Data Link Layer

PHY

DNS DHCP

Traffic Cond. and CoS Enforcement IIP Forwarding

PHB Enforcement

Subscriber Station or CPE

ASN(BS) + (ASN-GW)

CSN

QoS Signaling QoS Signaling

Applications

Service and Session Control Plane

Resource Control Plane

Monitoring Monitoring

802.16 Resource Control

Transport StratumA

ppl. and Services Stratum

Data/Transport Plane

SIP Signaling

Control Data Horizontal protocols

Management Plane

Agent

Other Legacy App

SIP UA

Appl. Signaling

QoS Signaling

Figure 5 WEIRD Architecture- high level view

The Data Plane(DPl) transfers the user/application data but also the control and management related data between the respective entities. The DPl may include functions and mechanisms to act upon the transported packets.

In a multi-domain environment the transport stratum may be split in inter and intra-domain parts.

While being included in end to end chains, the WEIRD system scope of contributions is mainly limited to the WiMAX network segment of the chain.

Figure 5 shows the simplified high level view of the WEIRD architecture, separated in strata and planes as described above. In the first version the WEIRD system supposes that medium and long term service and resource management is done quasi-statically, therefore the management plane functions are not detailed here. The resources at aggregated levels are provisioned statically in the management plane (static Service Level Agreements).

The Figure 5 architectural layered stack contains the entities represented are the SS/CPE, ASN (BS plus ASN-GW) and CSN, without detailing the function splitting in the ASN which depends on the IEEE 802.16 technology used (d/e). A proper Adapter here will be in charge of interfacing with the specific hardware.

User applications generally contains a graphical user interface, the media module and signaling modules (e.g. application signaling (e2e) and/or control signaling). Applications can exist without signaling capabilities (legacy) and also signaling capable (SIP based or on other protocols). The legacy applications are helped by an agent to signal their requirements.

In the general Control Plane only three kinds of horizontal signaling are explicitly presented here: direct application signaling, Session Initiation Protocol (SIP) signaling and resource-control signaling (for QoS purposes). As highlighted in the previous section, Next Step in Signaling (NSIS) protocols are used for carrying the latter information.

The WEIRD API Interface adapts the applications data and control flows to the Resource Control Plane and Data Plane. The parameters for QoS required are extracted and passed down to the Resource Controller (RC). The RC entities in SS/CPE, ASN, CSN use the NSLP communication services in order to talk each other and allocate resources for new application calls. Admission Control functions exist inside RC modules.

A specific treatment of resource allocation is done on the SS-BS segment of the end to end chain, where a light RC module exists in the Resource Control Plane (at NSIS level). A cross layer optimization can be applied here in the sense that the actual actions for resource reservation and allocation are performed at IEEE 802.16 level by mapping the higher layer flows on 802.16 Service Flows.

The functions necessary for user authentication, name

solving and IP addresses allocations (AAA, DNS, DHCP) are placed in the CSN entities.

The mobility is solved in the CPE and WiMAX part of the network by using WLANs and respectively IEEE 802.16e capabilities. For global mobility the Mobile IP (MIP) agents should exist in the CPE/SS (MIP “client”) , ASN ( Foreign Agent - FA and CSN (Home Agent – HA). The details of mobility signaling are not presented in this short description.

The WEIRD architecture can support the following mobility scenarios, as shown in the Figure 6:

M1 – intra BS – this is a micromobility solved “behind” a given instance of BS

M2 – inter-BS, intra-ASN – via R8 I/F M3 – inter-BS, intra-ASN via R6 and ASN-GW M4 - inter-BS, inter-ASN via R6 , ASN-GW1, R4, ASN-

GW2, R6. M5 – inter-BS inter-ASN plus IP mobility (MIP v4/6)

V. VALIDATING RESULTS: FOUR EUROPEAN TEST-BEDS

One of the key tasks of WEIRD project is to validate and demonstrate the results in particular test-beds. In fact, four test-beds will be implemented, in Finland, Italy, Portugal and Romania, each one built around a given scenario and employing specific technologies suitable for that scenario and

BS1

BS2

BS3

BS4

move ASN-GW2 (FA)

ASN-GW1 (FA)

HA

CSN

ASN1

R6

R6

R4

MSS

R3 M1-5

M2R8

M3

M4 M5

M3,4,5

ASN2

M5

Figure 6 WEIRD Architecture- mobility support

Figure 7 European WiMAX test-beds and their interconnection through

the GÉANT research network.

its associated applications. The test-beds will be used to assess the enhancements done at the different layers, including improvements on the physical layer (range and coverage extension, reliability, etc.), data link layer, QoS support, handover performance and access control mechanisms at the convergence layer. Moreover, new technologies needed to enlarge the capabilities and operating scenarios of WiMAX will be validated in the test-beds, in particular Radio over Fibre (RoF). Both fixed and mobile WiMAX solutions will be evaluated by all the test-beds, mostly in the first and second phase, respectively. The test-beds not only will provide wireless connectivity in their corresponding scenario but they will also be interconnected with each other through their national high-speed data networks and the pan-European GÉANT research network, as illustrated in Figure 6.

As the test-beds will have different profiles and employ

specific technologies, the scale of the testing and technology validation will be unusually large. Thus, the project is not only developing novel solutions aiming at enlarging the application domain of WIMAX but also implementing, testing and validating these solutions. This is considered as one of the most valuable and unique assets of the WEIRD project. In addition to the testing to be carried out locally at each test-bed, some applications like video and voice over IP will be evaluated through the interconnecting network.

Among the performance figures and capabilities to be tested in each particular test-bed we highlight achievable data rate, coverage, handover performance, QoS, security, reliability, compatibility between WiMAX equipment as well as between WiMAX and other access technologies (WiFi, 2G, 3G). Table I summarizes the main mobile WiMAX related demonstrations of the four test-beds.

TABLE I Key mobile demonstrations and related scenarios of test-beds

Demonstration: - Mobility capabilities - Full management functionality - LOS/NLOS - RoF

Demonstration: - Mobile video surveillance - A/V streaming - LOS - Real time data collection and transmission

Test-bed

Italy (3.5GHz)

Scenario: Telemedicine

Test-bed Portugal (3.5GHz)

Scenario: Fire prevention

Demonstration: - Mobility capabilities - Full management functionality - LOS/NLOS - VoIP

Demonstration: - Mobile capabilities - Multimedia transmission with error resilient coding - Range extension - Reliability

Test-bed Romania (3.5GHz)

Scenario: video conf., surveillance, e-learning

Test-bed Finland (3.5GHz)

Scenario: Environmental monitoring

The considered scenarios impose strict requirements to the

technical solutions and test-beds validating them. Among them we underline broadband transmissions in NLOS radio channels (all scenarios), wide coverage and very long ranges (volcano monitoring), very high mobility (fire prevention and monitoring) and high reliability (all scenarios). Fulfilling such

requirements, identified as one of the key technical challenges of the project, would certainly contribute to broaden the usability of WiMAX technology.

VI. CONCLUSIONS

Using WiMAX as a next generation access network, both for fixed and mobile connectivity, is a promising technology for a large number of real application scenarios in the academic, scientific and research community. This paper described how the WEIRD project is facing this challenging problem when the technology has to be used in few novel scenarios with high requirements in terms of mobility and Quality of Service. The analysis of these requirements highlighted the necessity to smoothly integrate, from the beginning, the WiMAX technology into the Next Generation Network architecture in order to be incorporate the existing features and to be compliant with the infrastructure that will be present in the market in the near future . When the applications might be not IMS compliant, as the case of some the scenarios described, some enhancements at client and network side will permit the communication of the user requirements in terms of QoS and mobility introducing new functional modules such as the WEIRD Agent and API, the NSIS signalling modules and the adapter.

At present, the WEIRD system architecture is being finalised and implemented. A first prototype of the WEIRD system will be released for evaluation in the test-beds in June 2007, while the final results of the tests and trials will be ready for the end of the project, expected in June 2008.

ACKNOWLEDGMENT

Authors would like to thank all the partners of the WEIRD consortium for their valuable contributions.

REFERENCES [1] “WiMAX End-to-End Network Systems Architecture, (Stage 2:

Architecture Tenets, Reference Model and Reference Points)”, WiMAX Forum, March 2006.

[2] K.Knightson, N.Morita and T.Towle, “NGN Architecture: Generic Principles, Functional Architecture, and Implementation”, IEEE Communications Magazine , p.49-55, October 2005.

[3] ITU-T Rec. Y.2011, “General Principles and General Reference Model for Next Generation Network.”

[4] R. Hancock, G. Karagiannis, J. Loughney, S. Van den Bosch, RFC 4080, “Next Steps in Signaling (NSIS): Framework”, June 2005, www.ietf.org

[5] WEIRD website and public deliverables: http://www.ist-weird.eu