O modelo implementado da camada PHY precisa ainda algumas melhorias.
A sincronização entre o transmissor e receptor é uma parte necessária a ser desenvolvida num trabalho futuro. Neste modelo, assumir atraso de recepção zero, assim os pacotes de detecção não são necessárias. Mas no caso real isto não pode acontecer. Um conjunto de métodos de sincronização podem ser desenvolvidos para o sistema OFDM (IEEE Std 802.16-2004, 2004). É um trabalho duro, mas com muitos desafios.
O padrão IEEE 802,16 vem com muitas características opcionais na camada PHY, que podem ser implementadas para melhorar o desempenho. O bloco opcional de codificação Turbo (BTC) (ETSI, 2005) podem ser implementado para melhorar o desempenho do FEC. Código de Bloco de Tempo espaço (STBC) (ETSI, 2005) podem ser empregadas em DL para fornecer diversidade de transmissão.
A codificação tempo espaço é sugerido no padrão 802.16a. Ela é usada para atingir Multi
Input Multi Output (MIMO), o que pode melhorar a qualidade da comunicação,
REFERENCIAS
AGILENT Technologies “Characterizing Digitally Modulated Signals with CCDF Curves”. 2000. Available from: http://www.agilent.com
AGILENT Technologies “Advanced Design System Capability Overview” . 2002
http://www.agilent.com
AGILENT Technologies “Advanced Design System”. 2005
http://www.agilent.com
BAUM S. DANIEL, “Simulating the SUI Channel Models”, IEE 802.163c01_53, April 12, 2001
BENOIT LOUAZEL. “Implementation of IEEE 802.16a in GloMoSim/QualNet”. Dublin City University School of Electronic Engineering. August 2004
CICCONETTI, C; LENZINI, L; MINGOZZI, E. “ Quality of Service Support in IEEE 802.16 Networks”. IEEE Network, , pp. 50-55, March/April 2006.
EKLUND, C.; MARKS R. B.; STANWOOD K. L.; WANG, S. “ IEEE Standard 802.16: A Technical Overview of the WirelessMAN Air Interface for Broadband Wireless Access”, IEEE Communications Magzine, vol.40, no.6, pp.98-107, June 2002.
ETSI, “Broadband Radio Access Networks (BRAN); HIPERMAN; Physical (PHY) Layer”. Standard TS 102 177 V1.2.1, 2005.
FUJITSU Microelectronics America, “WiMAX Technology and Deployment” White Paper, August 2004.
Networks” Available from:
http://images.globalknowledge.com/wwwimages/whitepaperpdf/WP_Simoneau_OSIModel .pdf, August, 2006.
HOYMANN, C. “Analysis and Performance Evaluation of the OFDM-Based Metropolitan Area Network IEEE 802.16”, Elsevier Computer Networks, Vol. 49, pp. 341-363, June 2005.
HOYMANN, C. “MAC Layer Concepts to Support Space Division Multiple Access in OFDM based IEEE 802.16” Wireless Personal Communications, Vol. 36, pp 363–385, 2006.
IEEE Std 802.11a-1999, “Supplement to Information Technology—Telecommunications and Information Exchange between Systems—Local and Metropolitan Area Networks— Specific Requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications: High Speed Physical Layer (PHY) in the 5 GHz Band,” 1999.
IEEE Std 802.16-2001, “IEEE Standard for Local and Metropolitan Area Networks, Part 16: Air Interface for Fixed Broadband Wireless Access Systems”, April 2002.
IEEE Std 802.16a-2003, “IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems—Amendment 2: Medium Access Control Modifications and Additional Physical Layer Specifications for 2–11 GHz”, January 2003.
IEEE Std 802.16-2004. “IEEE Standard for Local and Metropolitan Area Networks, Part 16: Air Interface for Fixed Broadband Wireless Access Systems”. October 2004.
IEEE Std 802.16e-2005. “IEEE Standard for Local and metropolitan area networks - Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems. Amendment
2: Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands”. February 2006.
IEEE WirelessMAN, “Inside the IEEE 802.16 Standard for Wireless Metropolitan Area Network”. May 2006.
ITU. International Telecommunication Union. “Recommendation X.509: Public-key and attribute certificate frameworks,2000”. Available from: http://www.itu.org.
KEPLER J.F.; KRAUSS T.P.; MUKTHAVARAM S. “Delay spread measurements on a wideband MIMO channel at 3.7 GHz”. IEEE: Vehicular Technology Conference (VTC2002 Fall), pp 2498 – 2502, 2002.
LANGTON C., “Orthogonal Frequency Division Multiplex (OFDM)” Tutorial. Available from: http://www.complextoreal.com/chapters/ofdm2.pdf, 2004.
LEITE, P. C.; PENEDO, A, C. “A tecnica de Transmissão OFDM”. Revista Cientifica Periódica – Telecomunicações – Volume 05 – Numero 01 – Junho 2002. ISSN 1516 – 2338.
LIBERTI, J, C. “Smart antennas for wireless communications : IS-95 and third generation CDMA applications” 1999.
MARKS, R., B. “The IEEE 802.16 WirelessMAN Standard for Wireless Metropolitan Area Networks”, IEEE C802.16-02/09. July 2002.
FIGUEIREDO F., L. “Fundamentos da Tecnologia WiMAX”. Centro de pesquisa de Desenvolvimento de Telecomunicações – CPqD. Available from:
www.cpqd.com.br/file.upload/sas1437_tecnologia_wimax_port_v02.pdf, 2006
MUPPALA, J, K; BANCHERDVANICH, T; TYAGI, A. “VoIP Performance on Differentiated Service Enabled Network,” Proc. of International Conference on Networks, pp. 419, Sep.2000.
OROZCO-BARBOSA, L; SIDDIQUI, S; YONGACOGLU, A. “ Efficient Integration of Voice and Data for Transmission Over Digital Subscriber Lines (DSL)”. IEEE Canadian Conference on Electrical & Computer Engineering. pp. 1505-1510. Ottawa. CANADA 2002.
ROHDE & SCHAWARZ “WiMAX General Information about the Standard 802.16”. White paper. Available from:
http://www.tessco.com/yts/industry/products/itm/pdf/rohde_general.pdf , 2006.
SIEMENS. “Overcoming the limitations of today’s fixed wired access technologies”, Available from:
http://www.siemens.com/Daten/siecom/HQ/IC/Internet/Marketing/WORKAREA/dsenf_re/template
data/English/document/binary/WiMAX20whitepaper20March202004_1161666.pdf . 2004.
SOUZA, L.; RIPOLL, A.; YANG, X.Y.; HERNANDEZ, P.; CORES, F.; “Designing a Video-on-Demand System for a Brazilian High Speed Network”
IEEE International Conference on Distributed Computing Systems Workshops pp: 43 – 43, 04-07 July 2006
THAPLIYAL, H.; KAMALA, R.V.; SRINIVAS, M.; “RSA encryption/decryption in wireless networks using an efficient high speed multiplier”. Personal Wireless
Communications, 2005. ICPWC 2005. 2005 IEEE International Conference on.
Page(s):417 – 419, 23-25 Jan. 2005.
UMTS “Universal Mobile Telecommunications System”. Available from:
http://www.umts.org/
VORNEFELD, U.; WALKE, C.; WALKE, B. “SDMA-Techniques for Wireless ATM”, IEEE Communications Magazine, Volume 37, Issue 11, Page(s):52 – 57, Nov. 1999.
V. ERCEG et. al, “An empirically based path loss model for wireless channels in suburban
environments,” IEEE JSAC, vol. 17, no. 7, July 1999, pp. 922 - 927.
V. ERCEG, K.V.S. HARI, M.S. SMITH, D.S. BAUM et al, “Channel Models for Fixed
Wireless Applications”, IEEE 802.16.3 Task Group Contributions 2003, Jun. 27
WiMAX FORUM. Available from: www.wimaxforum.org.
WiMAX FORUM: “Business Case Models for Fixed Broadband Wireless Access Based on WiMAX Tecnology and the 802.16 Standard”. Oct 2004.
SKLAR BERNARD SKLAR, “Digital Communications: Fundamentals and Applications,