INEL 5995 Weather Radar Network Topics

1. INEL 5995 Weather Radar Network Topics Prof. Héctor Monroy hmonroy@ece.uprm.edu Of. S-413

2. ¿Qué se estudia en esta parte del curso? Cómo se transmiten los datos que toman los radares (tales como los de CASA), desde el sitio de cada radar hasta un centro de recolección de datos

3. This slide is taken from a presentation by Brian C. Donovan, PhD Student UMass, Project Manager April 27, 2004 Puerto Rico Student Test Bed (IP-3)

4. Location Possibilities. Slide taken from a presentation by Brian C. Donovan, PhD Student UMass, Project Manager April 27, 2004 Mayagüez - Aguadilla 31.3 km Mayagüez – Arecibo 50.7 km Aguadilla – Arecibo 42.0 km Node Spacing Mayagüez - Aguadilla 31.3 km Mayagüez – Isabela 35.0 km Aguadilla – Isabela 12.5 km Node Spacing

5. Ejemplo: Cómo traer al RUM los datos colectados por un radar que se va a instalar próximamente en la Finca la Montaña, Aguadilla, en el sitio localizado en 18°28.465’ N, 67°07.267’ W

6. Proposed Location This slide is taken from a presentation by José Maeso and Jorge M. Trabal July 2004 UPRM Aguadilla (259’ over sea level)

7. Preguntas a responder inicialmente: • ¿Qué vamos a transmitir? • ¿Cómo lo vamos a transmitir? • ¿Qué mecanismo de propagación debemos usar? Luego de responder lo anterior, se ataca el problema de cómo diseñar el sistema para transmitir los datos a un centro de recolección.

8. Alternativas para enviar los datos desde los radares al RUM: • Poner datos en Removable Disk y mandarlos con alguien (bueno…si no hay prisa). • Mandarlos vía Wired Network • Mandarlos vía Wireless Network (si son varios radares, podría ser conveniente tener un centro de recolección, y de ahí enviar todos los datos al RUM, todo vía wireless).

9. Conviene sabor algo sobre Types of Networks: Private Networks • http://www.stratexnet.com/products/private_networks/ Mobile Networks • http://www.stratexnet.com/products/mobile_networks/ Fixed Networks • http://www.stratexnet.com/products/fixed_networks/

10. Tomado de los websites anterioresPRIVATE NETWORKS Private networks employ a variety of applications. Utility communications networks are a large user of microwave throughout the world, connecting oil and gas installations, pipelines, and even drilling platforms at sea. Campus-based university, health authority, and government networks are also an ideal application for microwave, providing connectivity between buildings that are co-located or distributed throughout a city or metropolitan area. These networks are self-contained, carrying PABX voice and LAN/WAN data traffic. National and regional TV networks also use microwave for contribution/distribution links between studios and broadcasting sites that are typically located on remote mountaintop locations where cable connectivity is impractical.

11. MOBILE NETWORKS Microwave radio is the medium of choice for mobile infrastructures worldwide, providing a compelling backhaul solution for operators of Mobile Cellular Networks. The demand for microwave, driven in the 1990's by the expansion of GSM in Europe, is now set to be eclipsed by the 2002 rollout of 3G mobile networks. 3G technology combines the typical benefits of microwave radio, including cost-effective and rapid deployment, easy capacity upgrade, and minimal operational costs, with the ability for operators to establish and maintain their own transmission links, instead of leasing expensive circuits from local fixed-line operators.

12. FIXED NETWORS A significant number of businesses remain disconnected from the information superhighway because they lack available wired broadband infrastructure. Wireless provides the perfect medium for breaking down the barriers of this "digital divide," whether in a city center or a remote rural community.

13. FIXED NETWORKS (cont.) Networks' microwave radio systems enable transmission connections in places where fiber cannot reach, where build is prohibitively expensive, when local authorities refuse or inhibit right-of-way for cable deployments, as a wireless backup for critical fiber links, or for dedicated wireless last-mile access.

14. Wired and wireless networks • Wired networks typically satisfy diverse requirements of different applications using a single protocol. This means the most stringent requirements for all applications must be met simultaneously. Wired networks may have data rates of Gbps and BERs of 10-12. • Currently exists a tremendous infrastructure of wired networks: the telephone system, the Internet, fiber optic, cables . This infrastructure could be used to connect wireless systems together into a global network. • Wired networks are mostly designed according to a layered approach, whereby protocols associated with different layers of the system operation are designed in isolation, with baseline mechanisms to interface between layers. • The layered approach (layering methodology) of wired networks reduces complexity and facilitates modularity and standardization, but it also leads to inefficiency and performance loss, due to the lack of a global design optimization.

15. Wired and wireless networks (cont. 1) • The situation is very different in a wireless network due to the nature of radiopropagation and broadcasting. • The wireless network must be able to locate a given user wherever it is among billions of globally distributed terminals (if it is a mobile terminal, the system must route the signal to a user as it moves at a certain speed). • The layers in a wireless system include: the link or physical layer (handles bit transmission over the communications medium); the access layer (handles shared access to the communications medium); the network and transport layers (which route data across the network and ensure end-to-end connectivity and data delivery); and the application layer (dictates the end-to-end data rates and delay constraints associated with the application). • Wireless networks required integrated and adaptive protocols at all layers, from the link layer to the application layer.

16. Wired and wireless networks (cont. 2) • The cross-layer protocol design of wireless networks requires interdisciplinary expertise in communications, signal processing, and network theory and design. • Wireless networks, at least in the near future, will continue to be fragmented, with different protocols tailored to support the requirements of different applications. Wireless networks have much lower data rates and higher BERs. • Interfacing between wired and wireless networks with different performance capabilities is a difficult problem.

17. Since different wireless applications have different requirements • There are many ways to segment this topic into different applications, systems, and coverage regions. • This has resulted in considerable fragmentation in the industry. • There are many different products, standards, and services being offered or proposed. • See the 55 pages New American Public Knowledge (by Kevin Werbach).

18. Lectura recomendada (cultura general sobre telecomunicaciones, para el gran público)

19. Conviene también leer algo sobre Planning Microwave Links. Ver, por ejemplo, http://www.stratexnet.com/about_us/our_technology/files/planning_article/taju95.html Ver también el website

20. Etapas de un diseño, desde el punto de vista de Comunicaciones: Circuitos y Antenas ( !OJO! Es diferente si se ve desde el punto de vista de Signal Processing o de Computer Science) • 1- Identificar características y requisitos de los datos a ser transmitidos (R, B, BER, SNR, SINR, etc.). • 2- Identificar rangos de frecuencia que se pueden usar (Recomendaciones y Normas ITU-R, FCC, IEEE). • 3- Identificar posibles alternativas de transmisión, y escoger la mejor (enfatizaremos LOS, y algún stándard IEEE802.11).

21. Etapas de un diseño, desde el punto de vista de Comunicaciones: Circuitos y Antenas (no de Signal Processing ni Computer Science) (cont. 1) • 4- Analizar preliminarmente las posibles rutas de propagación (usar Google Earth, USGS). • 5- Identificar las características generales de las posibles rutas de propagación (podrían usarse, por ejemplo, mapas de 1:25,000 de USGS en el Web). • 6- Seleccionar la ruta más viable y obtener la base de datos topográficos (Digital Elevation Models, USGS).

22. Etapas de un diseño, desde el punto de vista de Comunicaciones: Circuitos y Antenas (no de Signal Processing ni Computer Science) (cont. 2) • 7- Usar un software package (Radio Mobile, Radiosoft Comstudy, Planner, etc.) para analizar rutas y escoger alturas de antenas según requisitos de Zonas de Fresnel, reflexiones, etc. • 8- Repetir paso anterior con diferentes condiciones atmosféricas (K = 5/3, 4/3, 1, 2/3). Escoger ruta y dismensionar preliminarmente el sistema (Tx, Rx, antenas, líneas, etc.). • 9- Hacer pruebas de propagación (si hay los medios para tomar muestras), o usar Matlab para simular una señal recibida con los parámetros escogidos preliminarmente en el paso anterior.

23. Etapas de un diseño, desde el punto de vista de Comunicaciones: Circuitos y Antenas (no de Signal Processing ni Computer Science) (cont. 3) • 10- Usar Gaussian distribution, y determinar mean, std, etc. de la señal simulada (o muestra recibida) para adecuar el sistema a la confiabilidad de operación especificada. • 11- Usar Matlab para confirmar algunos resultados, haciendo el perfil topográfico de la ruta con la base de datos y simulando niveles de señal, de acuerdo al paso anterior. • 12- Dimensionar de nuevo el sistema. !Tener en cuenta cálculos de SAR, aunque se use baja potencia!

24. Etapas de un diseño, desde el punto de vista de Comunicaciones: Circuitos y Antenas (no de Signal Processing ni Computer Science) (cont. 4) • 13- Identificar proveedores de los equipos y componentes apropiados y hacer selección final del sistema, ajustado a los requisitos del diseño y a las Recomendaciones y Normas de ITU-R, FCC, IEEE, OSHA. • 14- Hacer lista de equipos, antenas, torres, cables…y componentes necesarios para instalar el sistema. • 15- Elaborar documento explicativo sobre las mediciones necesarias para optimizar el funcionamiento del sistema. • 16- Hacer un Resumen Ejecutivo.

25. Detalles de las Etapas de Diseño (1) • 1- Identificar características y requisitos de los datos a ser transmistidos ( R, B, BER, SNR, SINR, etc.).

26. -Application (Voice, sensing, file transfer, video teleconferencing, distributing control, paging and short messaging, Internet access, Web browsing, etc). -Systems (cellular telephone, wireless LANs, wide area wireless data, satellite, ad hoc wireless netwoks). -Coverage (building, city, regional, global). See p. 5 Wireless Comm., A. Goldsmith, Cambridge, 2005.

27. Requirements for different applications make it difficult to build one system that can satisfy all requirements simultaneously. Voice systems: • Have low data-rate requirements (around 20 kbps). • Can tolerate high probability of bit error (BERs of around 10-3), but • The total delay must be less than 100 ms or else it becomes noticeable to the end user (wired telephones have delay constraint of ≈30 ms, cellular phones ≈100 ms, voice over the Internet relaxes the constraint even further).

28. Data systems: Typically require much higher data rates (1-100 Mbps). Very small BERs (10-10 or less, and all bits received in error must be retransmitted). Do not have a fixed delay requirement.

29. Real-time video systems: Have high data-rate requirements coupled with the same delay constraints as voice systems. Paging and short messaging: Have very low data-rate requirements and no hard delay constraints.

30. Si queremos comunicar dos puntos del Oeste de PR…

31. Detalles de las Etapas de Diseño (2) • 2- Identificar rangos de frecuencia que se pueden usar (Recomendaciones y Normas ITU-R, FCC, IEEE).

32. The Electromagnetic Spectrum FREQUENCY 1 Hz 1 kHz 1 MHz 1 GHz 1012 Hz 1015 Hz 1021 Hz 1024 Hz 1027 Hz 1018 Hz 60 HzELECTRICPOWER FMRADIOTV AMRADIO VISIBLELIGHT MICROWAVES X-RAYS GAMMA COSMIC RADIO FREQUENCY RADIATION INFRARED ULTRAVIOLET NON-IONIZING RADIATION IONIZING RADIATION 3x108 3x105 3x102 3x10-1 3x10-4 3x10-7 3x10-10 3x10-13 3x10-16 3x10-19 WAVELENGTH (METERS) 4.1x10-15eV 4.1x10-6eV 4.1x100eV 4.1x1012eV ENERGY (ELECTRON VOLTS)

35. Hay que tener en cuenta las normas que rigen las telecomunicaciones A nivel mundial, las regulaciones las hace la Unión Internacional de Telecomunicaciones http://www.itu.int/home/ y la IEEE recomienda http://www.ieee802.org/11/. Pero en todos los países hay agencias que regulan a nivel nacional. Por ejemplo, en USA es la FCC http://www.fcc.gov/. Asignación: Visitar los sitios y aprender qué hace cada agencia. Tener en cuenta que algunas regulaciones de FCC, por ejemplo, están siendo cuestionadas. Las normas pueden variar ligeramente de un país a otro.

36. Ver en sitio de WebCt FCC Part_15_2_1_06.pdf, Part_15_Survey.ppt Will Changes toPart 15 of the FCC Rules & RegulationsEncourage Innovation? Opinions of Members of the FCC Technological Advisory Council

37. Un estándar de IEEE que ha revolucionado las telecomunicaciones (ver WebCt, documento 802_11tut.pdf)

38. Lectura recomendada: Unlicenced Wireless Broadband profiles (by Matt Barranca). Ver documento en WebCt, NewAmericanUnlicensed.pdf

39. El uso libre de bandas de frecuencia

40. Detalles de las Etapas de Diseño (3) • 3- Identificar alternativas de transmisión y mecanismos de propagación.

41. ACCESS SCHEMES • For radio systems there are two resources, frequency and time. Division by frequency, so that each pair of communicators is allocated part of the spectrum for all of the time, results in Frequency Division Multiple Access (FDMA). Division by time, so that each pair of communicators is allocated all (or at least a large part) of the spectrum for part of the time results in Time Division Multiple Access (TDMA). In Code Division Multiple Access (CDMA), every communicator will be allocated the entire spectrum all of the time. CDMA uses codes to identify connections. http://www.umtsworld.com/technology/cdmabasics.htm

42. ACCESS SCHEMES http://www.umtsworld.com/technology/cdmabasics.htm

43. CODING • CDMA uses unique spreading codes to spread the baseband data before transmission. The signal is transmitted in a channel, which is below noise level. The receiver then uses a correlator to despread the wanted signal, which is passed through a narrow bandpass filter. Unwanted signals will not be despread and will not pass through the filter. Codes take the form of a carefully designed one/zero sequence produced at a much higher rate than that of the baseband data. The rate of a spreading code is referred to as chip rate rather than bit rate. See coding process page for more details. http://www.umtsworld.com/technology/cdmabasics.htm

44. CODING

45. POWER CONTROL • CDMA is interference limited multiple access system. Because all users transmit on the same frequency, internal interference generated by the system is the most significant factor in determining system capacity and call quality. The transmit power for each user must be reduced to limit interference, however, the power should be enough to maintain the required Eb/No (signal to noise ratio) for a satisfactory call quality. Maximum capacity is achieved when Eb/No of every user is at the minimum level needed for the acceptable channel performance. As the MS moves around, the RF environment continuously changes due to fast and slow fading, external interference, shadowing , and other factors. The aim of the dynamic power control is to limit transmitted power on both the links while maintaining link quality under all conditions. Additional advantages are longer mobile battery life and longer life span of BTS power amplifiersSee UMTS power control page for more details. http://www.umtsworld.com/technology/cdmabasics.htm

46. MULTIPATH AND RAKE RECEIVERS • One of the main advantages of CDMA systems is the capability of using signals that arrive in the receivers with different time delays. This phenomenon is called multipath. FDMA and TDMA, which are narrow band systems, cannot discriminate between the multipath arrivals, and resort to equalization to mitigate the negative effects of multipath. Due to its wide bandwidth and rake receivers, CDMA uses the multipath signals and combines them to make an even stronger signal at the receivers. CDMA subscriber units use rake receivers. This is essentially a set of several receivers. One of the receivers (fingers) constantly searches for different multipaths and feeds the information to the other three fingers. Each finger then demodulates the signal corresponding to a strong multipath. The results are then combined together to make the signal stronger. http://www.umtsworld.com/technology/cdmabasics.htm

47. Rangos de f (ELF, ULF,VLF, LF, MF, HF, VHF, UHF, EHF…) y diferentes mecanismos de propagación. • LOS • Surface wave • Sky wave • Troposcatter • etc

48. Detalles de las Etapas de Diseño (4) • 4- Analizar preliminarmente las posibles rutas de propagación (usar Google Earth, USGS).

49. Ver WebCt, Google Earth