LW0050A LW0051A LW0052A LW0053A LW0054A LW0055A LW0056A JANUARY 2000 LW0057A LW0058A LW0059A LW0060A-CAN LW0061A-CAN LW0062A-CAN LW0063A-CAN Pro 11 Series Wireless Ethernet s eles Wircess Ac int Po R PW R INF R H T E CUSTOMER SUPPORT INFORMATION D LOA H M L Order toll-free in the U.S. 24 hours, 7 A.M.
TRADEMARKS TRADEMARKS USED IN THIS MANUAL Apple and AppleTalk are registered trademarks of Apple Computer, Inc. Digital is a trademark of Digital Equipment Corporation. HP is a registered trademark of Hewlett-Packard. IBM is a registered trademark of International Business Machines Corporation. Windows and Windows NT are registered trademarks of Microsoft Corporation. Sun is a registered trademark of Sun Microsystems, Inc. UL is a registered trademark of Underwriters Laboratories Incorporated.
PRO 11 SERIES WIRELESS ETHERNET FEDERAL COMMUNICATIONS COMMISSION AND CANADIAN DEPARTMENT OF COMMUNICATIONS RADIO FREQUENCY INTERFERENCE STATEMENTS This equipment generates, uses, and can radiate radio frequency energy and if not installed and used properly, that is, in strict accordance with the manufacturer’s instructions, may cause interference to radio communication.
NOM STATEMENT NORMAS OFICIALES MEXICANAS (NOM) ELECTRICAL SAFETY STATEMENT INSTRUCCIONES DE SEGURIDAD 1. Todas las instrucciones de seguridad y operación deberán ser leídas antes de que el aparato eléctrico sea operado. 2. Las instrucciones de seguridad y operación deberán ser guardadas para referencia futura. 3. Todas las advertencias en el aparato eléctrico y en sus instrucciones de operación deben ser respetadas. 4. Todas las instrucciones de operación y uso deben ser seguidas. 5.
PRO 11 SERIES WIRELESS ETHERNET 12. Precaución debe ser tomada de tal manera que la tierra fisica y la polarización del equipo no sea eliminada. 13. Los cables de la fuente de poder deben ser guiados de tal manera que no sean pisados ni pellizcados por objetos colocados sobre o contra ellos, poniendo particular atención a los contactos y receptáculos donde salen del aparato. 14. El equipo eléctrico debe ser limpiado únicamente de acuerdo a las recomendaciones del fabricante. 15.
ELECTRONIC EMISSION NOTICES Electronic Emission Notices This device complies with Part 15 of the FCC rules, ETSI 300-328, UL®, UL/C, TUV/GS, and CE. Operation is subject to the following two conditions: 1. This device may not cause harmful interference. 2. This device must accept any interference received, including interference that may cause undesired operation.
PRO 11 SERIES WIRELESS ETHERNET Contents Chapter Page 1. Introduction ............................................................................................................11 1.1 How to Use This Guide ..................................................................................11 1.2 Pro 11 Series Features ....................................................................................12 1.3 Pro 11 Series Product Line ........................................................................
CONTENTS Chapter Page 3.4.5 Station Control ......................................................................................35 3.4.6 Security (Authentication Feature) ......................................................35 3.5 Advanced Settings Menu ................................................................................37 3.5.1 Translation Mode ..................................................................................37 3.5.2 Performance ............................................
PRO 11 SERIES WIRELESS ETHERNET Chapter Page 4.7 Using the Upgrade Kit Program....................................................................70 4.8 Installation Troubleshooting ........................................................................74 4.9 Installing the PCMCIA Adapter Drivers in ODI Systems ............................75 5. Planning and Installing Wireless LANs ................................................................78 5.1 System Configurations................................
CONTENTS Chapter Page Appendix B. Specifications ......................................................................................107 B.1 Specifications for LW0050A–LW0053A and LW0055A–LW0058A ..........107 B.2 Specifications for LW0054A and LW0059A ................................................109 Appendix C. Wireless LAN Concepts ......................................................................112 C.1 Topology...................................................................................
PRO 11 SERIES WIRELESS ETHERNET Chapter Page E.10.1 Preamble ..............................................................................................136 E.10.2 PLCP Header ......................................................................................136 E.10.3 MAC Data ............................................................................................137 E.11 Most Common Frame Formats ....................................................................141 E.11.1 RTS Frame Format ...
CHAPTER 1: Introduction 1. Introduction 1.1. How to Use This Guide This guide contains instructions for overall planning and setting up your wireless LAN. It explains how to install each unit, plus how to install antennas and accessories. This guide contains: • Chapter 1, Introduction – Explains how to use this guide. • Chapter 2, Basic Installation – Explains how to install the Pro 11 Series units.
PRO 11 SERIES WIRELESS ETHERNET 1.2. Pro 11 Series Features • IEEE 802.11 Compliant – All Pro 11 Series units are fully compliant with the final IEEE 802.11 specification for wireless LANs, and thus support interoperability with other 802.11-compliant vendors. • Fully Integrated Product Family – One high-performance Access Point for all products in the series. • Increased Throughput – A 3-Mbps modem, with up to 2-Mbps data throughput.
CHAPTER 1: Introduction 1.3 Pro 11 Series Product Line These are Pro 11 Series Wireless Ethernet Units with Integral 2-dBi Antennas. Ethernet Access Point, Monitor Cable, Power Supply ............................LW0050A Single-Port Station Adapter, Power Supply ............................................LW0051A Four-Port Station Adapter, Power Supply ................................................LW0052A Ethernet Workgroup Bridge, Power Supply..............................................
PRO 11 SERIES WIRELESS ETHERNET Mobile workstations, such as laptops and hand-held devices, can roam between Access Points that belong to the same Extended Service Set (ESS). In an Extended Service Set, all Access Points have the same ESSID. When the access points are set up so that their coverage areas overlap, users can roam seamlessly from cell to cell. This means that there is no interruption of network connection when moving from one coverage area to the other through the overlap area.
CHAPTER 1: Introduction The Single-Port Station Adapter contains an embedded SNMP agent enabling effective management. Software upgrades are downloaded by TFTP via the Ethernet port or via the Wireless LAN and Access Point. Network connection is maintained while roaming between overlapping coverage areas. Transmission and reception can be continued while moving at high speed with no data-packet loss or duplication.
PRO 11 SERIES WIRELESS ETHERNET 1.3.4 WORKGROUP BRIDGE (LW0053A, LW0058A, OR LW0063A-CAN) The Workgroup Bridge is a high-speed, wide-range wireless LAN bridge that provides connectivity to remote Ethernet networks. The Workgroup Bridge communicates with the Access Points of the remote LANs, effectively creating an extended wireless network spanning sites situated up to 6 miles (9.7 km) apart (in Europe, this range is limited by ETSI regulations to 2.
CHAPTER 1: Introduction Network connection is maintained while roaming between overlapping cell coverage areas. Transmission and reception can be continued while moving at high speed with no data-packet loss or duplication. The PCMCIA Adapter is available in two models: • With two integrated omnidirectional retractable antennas (LW0054A). • With two external-antenna connector ports (LW0059A). 1.4 Pro 11 Functional Description 1.4.
PRO 11 SERIES WIRELESS ETHERNET 1.4.4 SINGLE-PORT STATION ADAPTERS The Single-Port Station Adapter is connected to a station’s network card. When the station sends a message, the Single-Port Station Adapter wirelessly forwards it to the Access Point. And when the Access Point receives a message destined for the station, it wirelessly forwards the message to the Single-Port Station Adapter. The first time the station sends a message, the station’s address is registered in the Access Point.
CHAPTER 1: Introduction 1.4.7 3-MBPS TYPE II PCMCIA ADAPTER The 3-Mbps Type II PCMCIA Adapter is inserted into the station’s PCMCIA slot and features identical operation to that of the Single-Port Station Adapter. As opposed to the Single-Port Station Adapter that connects to the station’s network card, the 3-Mbps Type II PCMCIA Adapter is the station’s network card.
PRO 11 SERIES WIRELESS ETHERNET 2. Basic Installation This chapter describes the physical installation of the Pro 11 Series units described in Chapter 1, with the exception of the PCMCIA Adapter. Installation for the LW0054A/LW0059A PCMCIA Adapter is described in Chapter 4. The Pro 11 Series features plug-and-play operation (the unit starts operating immediately after physical installation with a set of default operation parameters).
CHAPTER 2: Basic Installation The Access Points come with these additional components: • This guide. • A monitor connector cable for connecting the units to a monitor in order to perform Local Terminal Management functions (see Section 3.1). A proprietary MIB disk for performing remote-unit configuration and monitoring via SNMP is also available. Open the packaging carefully and make sure that none of the items listed above are missing. Do not discard packaging materials.
PRO 11 SERIES WIRELESS ETHERNET ADDITIONAL CONSIDERATIONS WHEN POSITIONING THE ACCESS POINT When positioning the Access Points, take into account the following additional considerations. Height Install the Access Point at least 5 feet (1.5 m) above the floor, clear of any high office partitions or tall pieces of furniture in the coverage area. The Access Point can be placed on a high shelf, or can be attached to the ceiling or a wall using a mounting bracket.
CHAPTER 2: Basic Installation 2.5 Connect the Unit to the Ethernet Port • Connect one end of an Ethernet 10BASE-T cable (not supplied) to the RJ-45 port on the rear panel of the unit (marked UTP). • Connect the other end of the connector cable to the Ethernet outlet: When connecting a Single-Port Station Adapter or Four-Port Station Adapter to a PC, use a straight cable. When connecting an Access Point or Ethernet Workgroup Bridge to a LAN, use a straight cable.
PRO 11 SERIES WIRELESS ETHERNET Name QLT Description Meaning Quality of reception H, M, and L LEDs not lit: Very-low-quality reception (less than -81 dBm) or not synchronized with Access Point. H and M LEDs not lit, L LED is lit: Low-quality reception (from -81 to -77 dBm), usually enabling 1-Mbps traffic. H LED not lit, M and L LEDs lit: Medium-quality reception (from -77 to -65 dBm), usually enabling 2Mbps traffic.
CHAPTER 3: Using the Local Terminal for Unit Setup and Management 3. Using the Local Terminal for Unit Setup and Management The Pro 11 Series units feature plug-and-play operation; the unit starts operating immediately following physical installation with a set of default parameters. Systemspecific configuration of the unit to meet specific requirements can be done via a local terminal (ASCII ANSI terminal or PC) connected to the unit.
PRO 11 SERIES WIRELESS ETHERNET To use Local Terminal Management: 1. Click an option number to open/activate the option. You may need to press Enter in some cases. 2. Press Esc to exit a menu or option. 3. Reset the unit after making configuration changes. 3.2 Configuration Screens Listed below are the menus, sub-menus, and sub-submenus in the terminal program that the Installer can edit. Default values are listed where applicable. Numbers in the table below indicate how to reach each option.
CHAPTER 3: Using the Local Terminal for Unit Setup and Management Table 3-1 (continued). Configuration Menus Menu Sub-Menu 1.4 Bridging 1.5 Station Sub-Submenu Default Values 1.4.1 LAN to WLAN Bridging Mode (Access Points only) Reject Unknown 1.4.2 Intelligent Bridging Period (Access Points only) 15 sec 1.4.3 IP Filtering Disabled 1.4.4 Tunneling Both Enabled 1.4.5 Broadcast Relaying Enabled 1.4.6 Unicast Relaying Enabled 1.5.1 Reset Unit Control 1.5.2 Load Defaults 1.6 Security 1.6.
PRO 11 SERIES WIRELESS ETHERNET Table 3-1 (continued). Configuration Menus Menu Sub-Menu Sub-Submenu Default Values 2.7 Main- 2.7.1 Auto Calibration Enabled tenance 2.7.2 Wait for Association Address (not in Access 2.7.3 Japan Call Sign Points) 3. Site 3.1 System Survey Counters 3.1.1 Display Ethernet and WLAN Counters 3.1.2 Display Rate Counters 3.1.3 Display Rx packets per frequency 3.1.4 Reset All Counters 3.1.5 Power Saving Counters 3.2 Survey Software 3.2.
CHAPTER 3: Using the Local Terminal for Unit Setup and Management 3.3 Main Menu Pro 11 Series (Workstation Bridge) Version: 4.211 Date: 25 Jun 1998 15:46:24 Monitor =================== 1 - System Configuration 2 - Advanced Settings 3 - Site Survey 4 - Access Control Select option > Figure 3-1. Main Menu. 3.4 System Configuration Menu Pro 11 Series (Workstation Bridge) Version: 4.4.
PRO 11 SERIES WIRELESS ETHERNET 3.4.1 STATION STATUS Station Status is a read-only sub-menu that displays the current values of the following parameters: • Unit’s Mode – Identifies the unit’s function. For example, if the unit is an Access Point, “AP” appears in this field. • Unit’s HW Address – Displays the unit’s unique MAC address. • Unit’s WLAN Address (Station Adapters or Workgroup Bridges) – The address associated with the unit. For the Single-Port Station Adapters, this is the address of the PC.
CHAPTER 3: Using the Local Terminal for Unit Setup and Management • Current Number of Authentications (Access Point Only) – Total number of stations currently authenticated with an Access Point. A station may be concurrently authenticated with several Access Points, but is associated with only one Access Point at a time. • Maximum Number of Authentications Since Last Reset (Access Point Only) – Maximum number of stations that were authenticated with an Access Point since the last reset. 3.4.
PRO 11 SERIES WIRELESS ETHERNET This parameter is set only in the LW0050A and LW0055A Pro 11 Access Point models. It is not accessible from any other Pro 11 unit. During the association process, all other stations learn the hopping sequence from the Access Point. Different co-located WLAN segments should use different hopping sequences. • Hopping Set (Access Points Only) – Hopping set (between 1 and 3) of the unit. Hopping sequences are grouped in several hopping sets.
CHAPTER 3: Using the Local Terminal for Unit Setup and Management • Transmit Antenna – Which antennas are used for transmission. During reception, a Pro 11 unit dynamically selects the antenna where reception is optimal. In contrast, the unit selects the antenna from which it will transmit before transmission. It usually uses the antenna last used for successful transmission. In models with external antennas, sometimes only a single antenna is used.
PRO 11 SERIES WIRELESS ETHERNET • Display Current Values – This read-only status screen displays current WLAN parameters. Press any key to return to the WLAN Parameters Menu. 3.4.4 BRIDGING The Bridging Menu contains the following options: • LAN to WLAN Bridging Mode (Access Points Only) – The options are: Reject Unknown – Type 0 to allow transmission of packets only to stations that the Access Point knows to exist in the Wireless LAN (behind the Wireless Bridge).
CHAPTER 3: Using the Local Terminal for Unit Setup and Management • Broadcast Relaying (Access Points Only) – Whether the unit performs broadcast relaying. When Broadcast Relaying is enabled, Broadcast packets originating in WLAN devices are transmitted by the Access Point back to the WLAN devices, as well as to the LAN. If it is disabled, these packets are sent only to the local wired LAN and are not sent back to the WLAN.
PRO 11 SERIES WIRELESS ETHERNET WEP, also referred to as the Privacy option, must be ordered specifically and is not supported by default. The security mechanism involves configuration of the following parameters: • Authentication Algorithm — This module operates in two modes: 0–Open System (default): no authentication, or 1–Shared Key authentication (for systems that have the privacy option implemented). • Default Key ID — The key to be used for the encryption of transmitted messages.
CHAPTER 3: Using the Local Terminal for Unit Setup and Management 3.5 Advanced Settings Menu Pro 11 Series (Workstation Bridge) Version: 4.4.1 Date: 26 May 199p 15:46:24 Advanced Settings menu ======================== 1 - Translation MOde 2 - Roaming 3 - Performance 4 - Radio 5 - Rate 6 - AP Redundancy Support 7 - Maintenance Select option > Figure 3-3. Advanced Settings Menu. Modification of most of the parameters in the Advanced Settings menu is limited to certified Black Box Technical Support only. 3.5.
PRO 11 SERIES WIRELESS ETHERNET • Power Save Support — If you enable Power Save Support on one of the WLAN stations (LW0054A or LW0059A only), you must also configure the Access Point unit. Power Save Support is influenced by two parameters: DTM interval on the Access Point side — Determines at which interval the Access Point will send its broadcast traffic (default 4 beacons).
CHAPTER 3: Using the Local Terminal for Unit Setup and Management • Power Level – Output power level at which the unit is transmitting. There are two possibilities, Low (4 dBm) or High (17 dBm), at the antenna connector. 3.5.4 RATE • Multi-Rate Support – When this parameter is enabled, the unit will automatically switch to the best transmission rate at any given time. When the parameter is disabled, the unit will always stay at the maximum rate configured in the WLAN Parameters menu. 3.5.
PRO 11 SERIES WIRELESS ETHERNET 3.6 Site Survey Menu Pro 11 Series (Workstation Bridge) Version: 4.4.1 Date: 26 May 1999 15:46:24 Site Survey menu =================== 1 - System Counters 2 - Survey Software 3 - Event Log 4 - Display Neighboring APs Select option > Figure 3-4. Site Survey Menu. The Site Survey Menu allows performing a site survey that helps you position your units and align their antennas of the units, as well as perform troubleshooting. 3.6.
CHAPTER 3: Using the Local Terminal for Unit Setup and Management 3.6.1.1 ETHERNET COUNTERS Ethernet counters display statistics about the unit’s Ethernet-port activity. The unit receives Ethernet frames from its UTP port and forwards them to its internal bridge, which decides whether or not to transmit them to the Wireless LAN. The units have a smart hardware filter mechanism which filters most of the frames on the LAN, and hardware-filtered frames are not counted.
PRO 11 SERIES WIRELESS ETHERNET acknowledge (there are no retransmissions for control frames). If the unit has retransmitted a frame for the maximum number of retransmissions, it will stop retransmitting the frame and drop this frame. Available Counters: • Total Transmitted Frames – The number of frames transmitted to the wireless media. The count includes the first transmission of data frames (without retransmissions), and also the number of control and management frames.
CHAPTER 3: Using the Local Terminal for Unit Setup and Management • Power Saving Aged – Total number of buffered frames that were aged out. This counter counts the number of frames dropped by the Access Point because a station did not poll those frames for a long period of time. • Power Saving Free Entries – The current number of free buffers (one frame each) available for power-save management. These buffers hold messages for stations that are currently in Power Save mode.
PRO 11 SERIES WIRELESS ETHERNET 3.6.1.4 USING THE RX PACKETS PER FREQUENCY HISTOGRAM Use the Display Rx Packets per Frequency option to see a histogram of the number of frames received on each channel. Pro 11 Series (Workstation Bridge) Version: 4.
CHAPTER 3: Using the Local Terminal for Unit Setup and Management 3.6.1.6 POWER-SAVING COUNTERS These counters apply only to Access Points. • PS stations — Number of associated stations currently working in Power Save mode. • Internally Discarded — Number of frames that were discarded because of aging. • Table — Valid only when Power Save mode is enabled. Station ID — Current number of buffered frames per station. Aged — Number of buffered frames that were aged out from buffer per station.
PRO 11 SERIES WIRELESS ETHERNET 4. Start the survey by selecting option (2) in the Survey Software menu in both units. When performing a site survey from a station to an Access Point (transmitting from the station to the Access Point), always begin with the station (select option [2] on the station). 5. On the transmit side, a screen appears displaying a table with the number of packets and the frequency at which each packet was transmitted (refer to Figure 3-6). This list is updated continuously.
CHAPTER 3: Using the Local Terminal for Unit Setup and Management # Pack 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 Ant 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 RSSI1 92 92 89 95 95 95 95 95 92 99 102 95 105 103 102 104 97 100 87 82 RSSI2 84 82 89 92 89 81 90 51 85 90 89 89 86 89 89 69 87 87 85 85 Bit_Err 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Freqs 76 75 58 51 46 10 31 4 5 77 43 22 58 51 46 64 78 33 71 70 Rate 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Quality ####
PRO 11 SERIES WIRELESS ETHERNET 3.6.4 EVENT LOG • Display Event Log — The error messages that the unit displayed since the last Load Full Factory Defaults reset or since the log was erased by Erase Event Log. The Event log stores events in four levels of error notifications: MSG (Message), WRN (Warning), ERR (Error), and FTL (Fatal). • Erase Event Log — Erases the event log. • Event Storage Policy — Defines severity policy for storage level of the event log.
CHAPTER 3: Using the Local Terminal for Unit Setup and Management The Access Control menu includes the following options: • Change Access Rights – This screen determines the level of access rights to the Pro 11 unit’s setup and configuration menus. When the unit is first installed, the default access right is Installer, and the default password is “user”: User – The Local Terminal Management menus are read-only for a user who does not possess the correct password.
PRO 11 SERIES WIRELESS ETHERNET 4. PCMCIA Adapter Installation, Setup, and Management This chapter describes how to install the PCMCIA Adapter and its associated firmware, drivers, and utilities. The PCMCIA Adapter Configuration and Site Survey utilities, which are used to set up and manage the card, are also described in this chapter. 4.1 Packing List The PCMCIA Adapter package should contain: • PCMCIA Adapter (LW0054A or LW0059A). • Drivers diskette. • Utilities diskette.
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management • We highly recommend that you remove all PCMCIA cards from the notebook prior to installing the PCMCIA Adapter. This will help to avoid conflicts during installation. If you have another network card installed (for example, an Ethernet card), you must remove it prior to installing the PCMCIA PC Card. 4.
PRO 11 SERIES WIRELESS ETHERNET 4.3.1.1 INSTALLING THE PCMCIA ADAPTER DRIVERS IN WINDOWS 98 1. Insert the PCMCIA Adapter in a free PCMCIA slot. Windows detects the unit and displays the New Hardware Found window. 2. When the Add New Hardware Wizard window appears, press Next. 3. Select the Search for best driver option and press Next. 4. Insert the Black Box drivers diskette, select the Floppy disk drives option, and press Next. 5. The installation wizard notifies you that the driver for the Brz 802.
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management 3. If you are running the Windows 95A operating system, refer to Section 4.3.1.2. If you are running the Windows 95B operating system, refer to Section 4.3.1.3. 4.3.1.2 FOR WINDOWS 95A 1. Insert the PCMCIA Adapter in the PCMCIA slot on your computer. Windows 95 detects the unit and displays the New Hardware Found window. 2. Select the Driver from disk provided by hardware manufacturer option and press OK. 3.
PRO 11 SERIES WIRELESS ETHERNET UNINSTALLING PCMCIA ADAPTER DRIVERS IN WINDOWS 95 1. Press the Windows Start button, select Settings, and then select Control Panel. Double-click on the PC Card icon, select Wireless LAN PC Card, and click Stop. Close all active applications. When asked to restart the computer, press No. 2. From the Windows Start menu, select Settings, and then select Control Panel. Double-click on the Network icon, click on the Configuration tab, select Brz 802.
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management 6. Press the Windows Start button and select Run. Type WINMSD and press OK. The Windows NT Diagnostics window appears. Figure 4-1. Windows NT Diagnostics Window. 7. Press IRQ and verify that IRQ 11 is not taken. If it is, find a free IRQ. For example, in the illustration, IRQ 2 is free. 8. Press Memory and verify that memory from D0000h to D3FFFh is not taken. If it is, find another free memory location, such as E0000h. 9.
PRO 11 SERIES WIRELESS ETHERNET UNINSTALLING PCMCIA ADAPTER DRIVERS IN WINDOWS NT 1. From the Windows Start menu, select Settings, and then select Control Panel. Double-click on the Network icon, click on the Configuration tab, select Brz 802.11 Wireless LAN PC Card, and click Remove. 2. Insert the Black Box Drivers diskette. From the Windows Start menu, select Run, and type a:\DrvClean. 3. When notified that the PCMCIA Adapter driver has been deleted, click Setup. 4. Restart the computer. 4.3.
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management 4.4 Installing the PCMCIA Adapter Utilities If a previous version of the PCMCIA Adapter utilities is installed, uninstall it before reinstalling the new version (as described in Section 4.4.1). To install the PCMCIA PC Card utilities: 1. Insert the Black Box utilities diskette. 2. From the Windows Start menu, select Run. Type A:\setup and click OK. 3. When the notification dialog box appears, click Setup. 4.
PRO 11 SERIES WIRELESS ETHERNET • Undo – Causes the window to display currently active values. This is useful if you started changing values and you want to start again from the current values. • Cancel – Closes the window without implementing any changes you made. • Apply – Implements any changes you made but leaves the window open. 4.5.1 STATION STATUS TAB The Station Status tab of the Wireless LAN Configuration utility displays information regarding the Adapter and its status.
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management 4.5.2 WLAN PARAMETERS TAB The WLAN Parameters tab of the Wireless LAN Configuration utility lets you view and edit basic Wireless LAN parameters of the Adapter. The WLAN Parameters tab contains the following parameters: • ESSID – An ASCII string of up to 32 characters used to identify a WLAN. The ESSID prevents the unintentional merging of two co-located WLANs.
PRO 11 SERIES WIRELESS ETHERNET • Import – Imports a configuration file to this unit, and overwrites all previous settings. • Export – Exports the current configuration of this unit to a file. NOTE Parameter changes take effect only after reset. 4.5.4 CONFIGURATION ACCESS TAB The Configuration Access tab of the Wireless LAN Configuration utility lets you log into the Adapter as User, Installer, or Technician, and lets you change the password.
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management IMPORTANT If you change the Installer password, do not forget it, or you will be unable to change the unit’s access rights. 4.5.5 POWER MANAGEMENT TAB The Power Management tab allows you to enable/disable Power Save mode and to configure Power Save mode parameters. Power Save mode is intended for laptops and hand-held computers, in order to conserve battery energy.
PRO 11 SERIES WIRELESS ETHERNET 4.5.6 SECURITY TAB The Security tab of the Wireless LAN Configuration utility allows you to set the security parameters of the station. The station in which the PCMCIA Adapter is installed can use one of the following authentication algorithms (as defined in the 802.11 standard): • Open System — Any station in the WLAN can associate with an Access Point and receive and transmit data (null authentication).
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management NOTE The default Key ID you enter for the PCMCIA Adapter must match the Key ID defined in the Access Point. Section 3.4.6 describes the procedure for setting the encryption keys for Access Points. It is recommended that you change the encryption keys periodically to enhance system security. 4.5.
PRO 11 SERIES WIRELESS ETHERNET Wireless LAN Configuration Station Status Security WLAN params Power Management ? Station Control Radio Maintenance Power level Configuration Access Performance Default Radio Status Low Low High High Hopping standard Country US FCC OK Undo Cancel Apply Figure 4-2. Radio Tab. The Radio tab contains the following parameters: • Power Level – Level of power at which the unit is operating. There are two possibilities, Low or High.
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management This tab is not visible when in User login mode. When in Installer login mode, you can see the parameters. When in Technician login mode, you can edit the parameters.
PRO 11 SERIES WIRELESS ETHERNET 2. Restart the computer, or stop the Adapter: From the Control Panel, double-click the PCMCIA Adapter icon, select the PCMCIA PC Card, and click Stop. Then eject and reinsert the card, or stop and refresh the driver as follows: 3. Right-click the My Computer icon on the desktop, choose Properties, and go to the Device Manager tab. Select Network Adapters - WLAN PC Card, and click Refresh. 4.
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management Site Survey for Wireless LAN Card Edit View Report Help Associated AP Alias: Sales AP address: 00-20-D6-B1-05-35 Signal Strength: -60dBm Poor Alias Fair AP Address Good Very Good Record Signal Alias Production 00-20-D6-21-0D-78 Iconize Marketing 00-20-D6-69-91-2C Survey Log Exit Figure 4-4. Site Survey utility. 4.6.
PRO 11 SERIES WIRELESS ETHERNET • Neighbor APs – This section, located at the bottom of the window, displays nearby Access Points (up to 4) from which the station is receiving a signal. For each Access Point, the following parameters are displayed: Alias – The alias you have assigned to the Access Point. To assign aliases to Access Point units, press the Alias button. If no alias has been assigned to the Access Point, this field displays “no alias.” AP Address – The IEEE MAC address of the Access Point.
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management • Menu Bar — The menu bar at the top of the window contains four menus: Edit, View, Report, and Help. These menus contain sub-menus which correspond in most cases to the buttons at the side of the window. Edit Menu – Three sub-menus: Record, Alias, and Exit. View Menu – Has two sub-menus: Survey Log and Iconize. Report Menu – Two sub-menus: Preview and Print (do not have corresponding buttons on side of window).
PRO 11 SERIES WIRELESS ETHERNET 5. Repeat steps 2 and 3 with other locations. The recorded readings should give you a good idea of where reception is good or bad, and where many Access Points overlap unnecessarily. 6. When you are done recording, press Print. A site survey report appears containing information about each recorded location, including signal strength of associated Access Point and of neighbor Access Points.
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management PCMCIA PC Card Upgrade Welcome This wizard assists you in upgrading your PCMCIA PC Card firmware, driver and applications. It is strongly recommended that you exit all Windows programs before running this wizard. Click “Close” to quit this wizard and exit all programs that are currently running. Click “Next” to continue. Close About 3. Click Next. The following dialog box is displayed.
PRO 11 SERIES WIRELESS ETHERNET 5. If the Adapter is already installed, stop the Adapter as follows: from the Control Panel, double-click the PCMCIA Adapter icon, select the PCMCIA PC Card, and click Stop. Remove the PCMCIA Adapter from the slot. Wait for about 15 seconds and then reinsert. Click Next. PCMCIA PC Card Upgrade Step 02 PCMCIA PC Card details Mac Address 00-20-D6-05-3D-57 Hardware version G Wep Enabled No Verify that both LEDs blink, otherwise contact Technical Support.
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management PCMCIA PC Card Upgrade Step 03 Downloading firmware..... Note: This process takes approximately 15 seconds. Do not be alarmed if it seems as if the computer has frozen for the diuration of the downloading of the firmware. Close About 8. When the firmware has completely downloaded, the following dialog box is displayed.
PRO 11 SERIES WIRELESS ETHERNET PCMCIA PC Card Upgrade Step 05 PCMCIA PC Card Upgrade completed Press “Finish” to exit.
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management Problem 1: Adapter does not function properly. 1. Check Device Manager for conflicts with any other devices and drivers. 2. Right click My Computer, Properties, and then the Device Manager tab. 3. Click Network Adapters to verify status of the Adapter—an exclamation mark next to the card indicates a conflict. Problem 2. There is a resolution conflict. 1. Double-click the PCMCIA PCI Card. 2. Select the Resources tab. 3.
PRO 11 SERIES WIRELESS ETHERNET 2. Copy all files from the DOSODI directory on the driver to the NetWare client directory. (If you already have a NET.CFG file that you want to keep, copy and paste the BRZWLAN section from the sample NET.CFG file supplied by Black Box, into your existing file.) 3. In order to log into a NetWare server, run the following files (make sure that the NET.CFG and the BRZWLAN.INI files are located in the directory from which you run the following files): • LSL.
CHAPTER 4: PCMCIA Adapter Installation, Setup, and Management 3. Enter the ESSID as defined in the Access Point (if using default ESSID, do not change). 4. Reset/restart the computer. NOTE Default ESSID is ESSID1 in capital letters. TROUBLESHOOTING ODI INSTALLATION The following paragraphs provide information that can help in the event of problems encountered in the ODI drivers installation. • It is important to note which net.cfg and brzwlan.ini is used.
PRO 11 SERIES WIRELESS ETHERNET 5. Planning and Installing Wireless LANs Models LW0050A through LW0054A are equipped with two integrated 2-dBi omnidirectional antennas and are suitable for indoor, short- to medium-range installations. Models LW0055A through LW0059A are equipped with two customized female connectors for use with a range of external antennas.
CHAPTER 5: Planning and Installing Wireless LANs There are three types of Single-Cell Configuration: • Point-to-Point • Point-to-Multipoint • Mobile Applications Each type is explained in the following sections. 5.1.1.1 POINT-TO-POINT Point-to-Point installations require directional antennas at either end of the link. To select the best antenna for a specific application, consider the following factors: • Distance between sites • Required throughput • Clearance between sites • Cable length. 5.1.1.
PRO 11 SERIES WIRELESS ETHERNET 5.1.1.4 EXTENDING THE LAN WITH WLAN BRIDGING The figures in this section demonstrate how the Workgroup Bridge (LW0053A) can be used with an Access Point to extend a regular network with a wireless link. Access Point (LW0050A or LW0055A) Bridge (LW0053A or LW0058A) Figure 5-1. Connecting Remote Offices to Main Office Network.
CHAPTER 5: Planning and Installing Wireless LANs The Workgroup Bridge (LW0053A) also enables connectivity between a wireless LAN and individual workstations or workgroups located outside the LAN. The Workgroup Bridge enables these wireless stations in its coverage area to communicate with the wireless LAN and gain access to all of the network resources such as file servers, printers and shared databases.
PRO 11 SERIES WIRELESS ETHERNET 3. Look at the Station Adapter’s front-panel LED indicators, or the PCMCIA PC Card’s Site Survey application, to check signal strength. 4. Make any necessary adjustments. For example, adjust the antennas, the location of the Station Adapter, or the location of the Access Point. 5. Set up the other workstations. Figure 5-3. Single-Cell Configuration. 5.1.
CHAPTER 5: Planning and Installing Wireless LANs • Any workstation situated in the overlapping area can associate and communicate with either Access Point #1 or Access Point #2. • Any workstation can move seamlessly through the overlapping coverage areas without losing its network connection. This attribute is called Seamless Roaming. To set up overlapping cells: 1. Install an Access Point (refer to Chapter 2). Be sure to position the Access Point as high as possible. 2.
PRO 11 SERIES WIRELESS ETHERNET 5.1.3 MULTICELL CONFIGURATION Areas congested by many users and a heavy traffic load may require a multicell structure. In a multicell structure, several Access Points are installed in the same location. Each Access Point has the same coverage area, thereby creating a common coverage area that increases aggregate throughput. Any workstation in the overlapping area can associate and communicate with any Access Point covering that area. To set up a multicell: 1.
CHAPTER 5: Planning and Installing Wireless LANs Access Point Access Point Access Point Common Coverage Area Figure 5-4. Multicell Configuration. 5.1.4 MULTI-HOP CONFIGURATION (RELAY) When you need to connect two sites and no line of sight exists between them, an Access-Point/Workstation-Bridge pair can be positioned at a third location where line-of-sight exists with each of the original locations. The third location then acts as a relay point.
PRO 11 SERIES WIRELESS ETHERNET 4. When an Access Point and Workstation Bridge communicate over the wireless LAN, set them both to the same ESSID. For example, set the Access Point of the main office and the Workstation Bridge of the first Access-Point/ Workstation-Bridge relay pair to the same ESSID. Also, set the Access Point of the last Access-Point/Workstation-Bridge relay and the Workstation Bridge of the remote site to the same ESSID; this ESSID should be different from the first ESSID.
CHAPTER 5: Planning and Installing Wireless LANs Access Point Figure 5-6. Access Point LAN in a Typical Office Environment. 5.2.1 SITE-SELECTION FACTORS The Pro 11 Series Wireless Ethernet products are designed to operate efficiently under a wide range of conditions. The following guidelines are provided to help you position the units to ensure optimum coverage and operation of the wireless LAN.
PRO 11 SERIES WIRELESS ETHERNET Site Selection for Access Points When positioning Access Points, take into account the following additional considerations. HEIGHT Install the Access Point at least 5 feet (1.5 m) above the floor, clear of any high office partitions or tall pieces of furniture in the coverage area. The Access Point can be placed on a high shelf, or can be attached to the ceiling or a wall using a mounting bracket.
CHAPTER 5: Planning and Installing Wireless LANs sufficient to ensure good performance levels. However, in cases where multipath propagation exists, we recommend that two antennas be used. This takes advantage of space-diversity capabilities. By using two antennas per unit, the system can select the best antenna on a per-packet basis (every few milliseconds). Multipath propagation is to be expected when there are potential reflectors between the main and remote sites.
PRO 11 SERIES WIRELESS ETHERNET Use the following table as a guideline to predict the effects of different materials. Table 5-1.
CHAPTER 5: Planning and Installing Wireless LANs Closed Indoor Areas A floor divided into individual offices by concrete, masonry, or sheet-rock walls. A house is also a closed indoor area. The suggested maximum distance between a standard Access Point and a workstation is 150 ft. (50 m). 5.
PRO 11 SERIES WIRELESS ETHERNET window frames or metal film anti-glare windows in the transmission path. Install outdoor antennas high enough to avoid any obstacles which may block the signal. Minimal Path Loss Path loss is determined mainly by several factors: • Distance between sites. Path loss is lower and system performance better when distances between sites are shorter. • Clearance. Path loss is minimized when there exists a clear line of sight.
CHAPTER 5: Planning and Installing Wireless LANs Point-to-Point A point-to-point link is based on the use of one Access Point with external antennas (LW0055A) and one adapter (LW0056A–LW0059A). The Access Point and the Workstation Bridge must be equipped with one or two directional antennas. The necessary antenna gain depends on the required range and performance.
PRO 11 SERIES WIRELESS ETHERNET If the received signal quality is lower than expected for this antenna/range combination, change antenna height and verify RF cable connections. Antenna Diversity In applications where no multipath propagation is expected, a single antenna is sufficient to ensure good performance levels. However, in cases where multipath propagation exists, we recommend that two antennas be used. This takes advantage of space-diversity capabilities.
CHAPTER 5: Planning and Installing Wireless LANs 5.3.6 LINK DISTANCE Link distance is the maximum distance between the Access Point and the station adapter, usually related to point-to-point installations using external antennas. For open outdoor areas with an unobstructed line of sight between the Access Point and the wireless bridge, the suggested maximum distance is: • up to 7 miles (10 km) in the USA (with an LW0055A Access Point with external antennas) • up to 2.
PRO 11 SERIES WIRELESS ETHERNET 5.4.2 SPURIOUS RADIO FREQUENCY EMISSIONS The regulations referred to in the previous section also specify maximum “out-ofband” radio frequency emissions. Install a filter as close as possible to the Pro 11 unit’s connector. 5.4.3 LIGHTNING PROTECTION Lightning protection is designed to protect people, property, and equipment by providing a path to ground for the lightning’s energy.
CHAPTER 6: Upgrade Procedure 6. Upgrade Procedure IMPORTANT! Please read the information below before proceeding with any upgrades. There are two options for upgrading to the Pro 11 Series: 1. Send in your Pro Series equipment, and we will upgrade the units to the Pro 11 802.11 standard for a service fee. 2. Download the software at no charge from the Black Box FTP site and perform the upgrade yourself.
PRO 11 SERIES WIRELESS ETHERNET Table 6-1. Upgrade Files Current Version of Unit Flash Erase Software Download File Name File Name LW0050A LW0051A, LW0052A, LW0053A 3.2, 3.38, 3.42, 3.50 3.52, 4.204, 4.41 3.62, 4.210, 4.211, 4.310, 4.41 download erase erase_fw eanaf eanafb ap_fw eansf eansfb sawb_fw The current version and type of the unit determine the files used for upgrade. For example, when upgrading LW0050A from version 3.52 to version 4.4.1, use the erase and eanafb files.
CHAPTER 7: System Troubleshooting 7. System Troubleshooting This troubleshooting guide provides answers to some of the more common problems which may occur when installing and using the Pro 11 Series products. If problems not mentioned in this guide should arise, checking the Ethernet and WLAN counters may help. If the problem persists, call Technical Support. 7.1 Troubleshooting Guide Problem and Indication Possible Cause Corrective Action No power to unit. 1. Power cord is not PWR LED is off.
PRO 11 SERIES WIRELESS ETHERNET Problem and Indication Possible Cause Corrective Action Failure to establish wireless link (LW0055A– LW0058A) 1. Power supply to units may be faulty. 2. Cables may be improperly connected. 3. There may be some problem with antenna installation. 1. Verify power to units. 2. Verify that all cables are connected securely. 3. Refer to the previous section and verify wireless link between the units. 4.
CHAPTER 7: System Troubleshooting Problem and Indication Possible Cause Wireless link established, but there is no Ethernet activity (Station Adapters). 1. Ethernet port on Network Interface card is faulty. 2. Ethernet port of unit is faulty. 3. UTP cable is faulty. 1. Verify that the LINK LED is lit and solid at the NIC port. If this is not the case, the port is inactive. Try using another UTP cable or another workstation. 2. Ping the unit to check the Ethernet port.
PRO 11 SERIES WIRELESS ETHERNET Problem and Indication High-quality signal but throughput is poor. Possible Cause 1. Too much interference or multipath propagation. 2. Ethernet port of the unit may be faulty. Corrective Action 1. Move the unit or the antennas out of the range of interference. • Check counters to see if more than 10% of total transmitted frames are retransmitted fragments (see Section 3.6.1). • Check if more than 10% of total received data frames are bad fragments (see Section 3.6.1). 2.
CHAPTER 7: System Troubleshooting Problem and Indication Possible Cause Corrective Action Unit associates with the wrong Access Point. In a multicell structure with overlapping cells, the units may not associate with the closest Access Point. For a unit to associate with a specific Access Point, assign a unique ESSID to the Access Point and to all the units you want to include in that wireless network. Reduced performance in a multiAccess Point configuration.
PRO 11 SERIES WIRELESS ETHERNET Appendix A. Supported MIBs and Traps A.1 Supported MIBs All products in the Pro 11 Series contain an embedded SNMP (Simple Network Management Protocol) agent. All functions can be accessed from the Management Information Base (MIB) using an SNMP application. Pro 11 Series agents support the following MIBs: • MIB-II (RFC1213) • BRIDGE-MIB (RFC1286) • Pro 11 Private MIB The Pro 11 Private MIB can be viewed by opening the MIB file brz11prv.mib.
APPENDIX A: Supported MIBs and Traps Trap Variables Description brzAProamingIn brzTrapSTAMacAddr A station has roamed into this Access Point coverage area. The trap contains the MAC address of the associated station. brzAPassociated brzTrapSTAMacAddr A new station is associated with this Access Point. The trap contains the MAC address of the associated station. brzAPdisassociated brzTrapSTAMacAddr A station has disassociated itself from this Access Point.
PRO 11 SERIES WIRELESS ETHERNET Trap Variables brzWlanStatus brzTrapToggle brzTrapMacAddress The wireless media condition has changed. An ON value is sent when the wireless LAN quality for a station or Access Point drops below the WLAN trap threshold. An OFF value is sent if the quality improves beyond the threshold. The current value of wireless LAN is also sent. brzWlanStatusOfStation brzTrapToggle brzTrapMacAddress The quality of the wireless connection to the Access Point has changed.
APPENDIX B: Specifications Appendix B. Specifications B.1 Specifications for LW0050A–LW0053A and LW0055A–LW0058A WIRED LAN INTERFACE Compliance — Ethernet/IEEE 802.3 CSMA/CD standard Physical Interface — 10BASE-T Network Operating Systems Supported — All Network Protocols Supported — All WIRELESS LAN INTERFACE Compliance — IEEE 802.
PRO 11 SERIES WIRELESS ETHERNET CONFIGURATION AND MANAGEMENT Configuration and Setup — Via Local Monitor port (serial RS-232) SNMP Management — SNMP agents: MIB II, Bridge MIB, WLAN MIB, and private MIB; Access via: Wired LAN, Wireless LAN Site Survey — Via Local Monitor port (serial RS-232), via SNMP Indicators — Power on, Wired LAN activity, Wireless LAN synchronization, Wireless LAN signal quality/Load Software Upgradable — Through TFTP download SYSTEM CONSIDERATIONS Range (Access Point to Station) — Dep
APPENDIX B: Specifications ELECTRICAL External Power Supply — 100 to 250 VAC, 50 to 60 Hz, 0.5 A Input Voltage — 5 VDC Power Consumption — 1.5 A peak, 1.2 A average PHYSICAL Size — 5.1"H x 3.4"W x 1.35"D (13 x 8.6 x 3 cm) without antennas and power supply Weight — 0.9 lb. (0.4 kg) without antennas and power supply B.2 Specifications for LW0054A and LW0059A WIRED LAN INTERFACE Physical Interface — PC Card type II/PCMCIA 2.
PRO 11 SERIES WIRELESS ETHERNET Sensitivity — 1 Mbps: -81 dBm; 2 Mbps: -75 dBm; 3 Mbps: -67 dBm Modulation — Multilevel GFSK Demodulation Technology — DSP-based with adaptive equalization Antenna Diversity — Two antennas, selected for use on a packet basis Frequency Accuracy — ±10 PPM Approvals of Compliance — FCC part 15, ETS 300-328, UL, UL/C, TUV/GS, CE CONFIGURATION AND MANAGEMENT Configuration and Setup — Via application Site Survey — Via application Indicators— Link Status, Data Traffic Software Upgra
APPENDIX B: Specifications ENVIRONMENTAL Operating Temperature — 32 to 105°F (0 to 40°C) Operating Humidity — 5 to 95% noncondensing ELECTRICAL Power — Via network PC Input Voltage — 5 VDC Power Consumption — XMT: 365 mA peak; RCV: 280 mA peak PHYSICAL Size — Standard PCMCIA Type II Weight — 1.1 oz.
PRO 11 SERIES WIRELESS ETHERNET Appendix C. Wireless LAN Concepts Wireless LAN technology is becoming increasingly popular in large-scale and complex wireless networks, as more and more users are discovering its reliability and high performance. Originally designed for indoor office applications, today’s wireless LANs can be used for both indoor client-server or peer-to-peer networks and outdoor point-topoint or point-to-multipoint remote-bridging applications.
APPENDIX C: Wireless LAN Concepts C.1.2 WIRELESS LAN TOPOLOGY Wireless LANs allow workstations to communicate and to access the network using radio propagation as the transmission medium. Wireless LANs can be connected to existing wired LANs as an extension, or can form the basis of a new network. While adaptable to both indoor and outdoor environments, wireless LANs are especially suited to indoor locations such as office buildings, manufacturing floors, hospitals, and universities.
PRO 11 SERIES WIRELESS ETHERNET Each wireless LAN cell requires some communications and traffic management. This is coordinated by an Access Point which communicates with each wireless station in its coverage area. Stations also communicate with each other via the Access Point, so communicating stations can be hidden from one another. In this way, the Access Point functions as a relay, extending the range of the system.
APPENDIX C: Wireless LAN Concepts C.2 Roaming When any area in the building is within reception range of more than one Access Point, the cells’ coverage is said to overlap. Each wireless station automatically establishes the best possible connection with one of the Access Points. Overlapping coverage areas are an important attribute of the wireless LAN setup, because this enables seamless roaming between overlapping cells.
PRO 11 SERIES WIRELESS ETHERNET Access Point Access Point Access Point Common Coverage Area Figure C-4. The Common Coverage Area of a Multi-cell Structure. C.4 Dynamic Rate Switching The data rate of each station is automatically adjusted according to the received signal quality. Performance (throughput) is maximized by increasing the data rate and decreasing re-transmissions.
APPENDIX C: Wireless LAN Concepts C.6 Fragmentation Fragmentation of packets into shorter fragments adds protocol overhead and reduces protocol efficiency when no errors are expected, but reduces the time spent on re-transmissions if errors are likely to occur. When errors and retransmissions are occurring, no fragmentation or longer fragment length adds overhead and reduces efficiency. C.
PRO 11 SERIES WIRELESS ETHERNET Appendix D. Radio Signal Propagation D.1 Introduction This section explains and simplifies many of the terms relating to antennas and RF (Radio Frequency) used when dealing with an RF installation system. The following diagram depicts a typical radio system. Receiving Antenna Transmitting Antenna Medium Transmitter Receiver Information (Data/Voice) to Be Transmitted Figure D-1. A Typical Radio System. A radio system transmits information to the transmitter.
APPENDIX D: Radio Signal Propagation D.2 RF Terms and Definitions dB An abbreviation for decibel, a comparative measure of signal strength. dBm An absolute measure of signal strength. 0 dBm = 1 milliwatt. (See “RF Power Level” below.) RF POWER LEVEL RF power level at either the transmitter output or the receiver input is expressed in watts. It can also be expressed in dBm.
PRO 11 SERIES WIRELESS ETHERNET Attenuation is expressed in dB as follows: PdB = -10 × Log (Pout/Pin) For example: If, because of attenuation, half the power is lost (Pout/Pin = 1/2), then attenuation in dB is -10 × Log (1/2) = 3 dB PATH LOSS Loss of power of an RF signal traveling (propagating) through space. It is expressed in dB. Path loss depends on: • The distance between transmitting and receiving antennas. • Line-of-sight clearance between the receiving and transmitting antennas. • Antenna height.
APPENDIX D: Radio Signal Propagation Side Lobes The radiation lobes in any direction other than that of the main lobe. Omnidirectional Antenna An antenna that radiates and receives equally in all directions in azimuth. The following diagram shows the radiation pattern of an omnidirectional antenna with its side lobes in polar form. Side lobe Main lobe Figure D-3. Side View. Figure D-4. Top View. Directional Antenna An antenna that radiates and receives most of the signal power in one direction.
PRO 11 SERIES WIRELESS ETHERNET Antenna Beamwidth The directiveness of a directional antenna. Defined as the angle between two halfpower (-3 dB) points on either side of the main lobe of radiation. SYSTEM CHARACTERISTICS Receiver Sensitivity The minimum RF signal power level required at the input of a receiver for certain performance. EIRP (Effective Isotropic Radiated Power) The power transmitted by an antenna. Equal to the transmitted output power minus cable loss plus the transmitting antenna gain.
APPENDIX D: Radio Signal Propagation In conclusion, the received signal power is above the sensitivity threshold, so the link should work. The problem is that there is only a 2-dB difference between received signal power and sensitivity. Normally, a higher margin is desirable because of fluctuation in received power as a result of signal fading.
PRO 11 SERIES WIRELESS ETHERNET • Interference Interference may be caused by another system on the same frequency range, external noise, or some other co-located system. LINE OF SIGHT An optical line of sight exists if you can see one antenna from the other. Clear Line of Sight A clear line of sight exists when no physical objects obstruct viewing one antenna from the location of the other antenna.
APPENDIX E: IEEE 802.11 Technical Tutorial Appendix E. IEEE 802.11 Technical Tutorial The purpose of this chapter is to give you a basic overview of the IEEE 802.11 Standard. You’ll be able to understand the basic concepts, principles of operation, and reasons behind some of the features of the Standard. The document does not cover the entire Standard and does not provide enough information for you to implement an 802.11-compliant device (for this purpose you should refer to the Standard itself). E.
PRO 11 SERIES WIRELESS ETHERNET Distribution System Access Point Access Point BSS BSS ESS Figure E-1. Typical 802.11 LAN. The standard also defines the concept of a “portal.” A portal is a device that interconnects an 802.11 LAN and another 802 LAN. This concept is an abstract description of part of the functionality of a “translation bridge.” Even though the standard does not necessarily require it, typical installations will have the Access Point and the Portal on a single physical entity.
APPENDIX E: IEEE 802.11 Technical Tutorial Beyond the standard functionality usually performed by MAC Layers, the 802.11 MAC performs other functions that are typically related to upper-layer protocols, such as Fragmentation, Packet Retransmissions, and Acknowledges. E.3 The MAC Layer The MAC Layer defines two different access methods—the Distributed Coordination Function and the Point Coordination Function: E.3.
PRO 11 SERIES WIRELESS ETHERNET In order to overcome these problems, 802.11 uses a Collision Avoidance (CA) mechanism together with a Positive Acknowledge scheme, as follows: 1. A station wanting to transmit senses the medium. If the medium is busy, then it delays. If the medium is free for a specified time (called Distributed InterFrame Space [DIFS] in the standard), then the station is allowed to transmit. 2.
APPENDIX E: IEEE 802.11 Technical Tutorial The following diagrams show an exchange between stations A and B, and the NAV setting of their neighbors: G1=SIFS G3 =DIFS CW=Contention Window G3 Src RTS Data G1 Dest G1 G1 CTS Ack G3 Other NAV (RTS) CW Next MPDU NAV (CTS) Defer Access Backoff After Defer Figure E-2. Transaction Between Stations A and B. The NAV State is combined with the physical carrier sense to indicate the busy state of the medium. E.3.
PRO 11 SERIES WIRELESS ETHERNET However, it doesn’t make sense to introduce a new LAN protocol that cannot deal with packets 1518 bytes long which are used on Ethernet, so the committee decided to solve the problem by adding a simple fragmentation/reassembly mechanism at the MAC Layer. The mechanism is a simple Send-and-Wait algorithm, where the transmitting station is not allowed to transmit a new fragment until one of the following happens: 1. It receives an ACK for the said fragment, or 2.
APPENDIX E: IEEE 802.11 Technical Tutorial E.3.5 INTER FRAME SPACES The Standard defines four types of Inter-Frame Spaces, which are used to provide different priorities: • SIFS, Short Inter-Frame Space, separates transmissions belonging to a single dialog (e.g. Fragment-Ack), and is the minimum Inter-Frame Space. There is always at most one single station to transmit at any given time, so it has priority over all other stations.
PRO 11 SERIES WIRELESS ETHERNET The 802.11 standard defines an Exponential Backoff Algorithm that must be executed in the following cases: • When the station senses the medium before the first transmission of a packet, and the medium is busy • After each retransmission, and • After a successful transmission The only case when this mechanism is not used is when the station decides to transmit a new packet and the medium has been free for more than DIFS.
APPENDIX E: IEEE 802.11 Technical Tutorial Both methods are valid. A method is chosen according to the power consumption/performance trade-off. E.4.1 THE AUTHENTICATION PROCESS Once the station has located an Access Point, and decides to join its BSS, it goes through the Authentication Process. This is the interchange of information between the Access Point and the station, where each side proves the knowledge of a given password. E.4.
PRO 11 SERIES WIRELESS ETHERNET E.6 Keeping Synchronization Stations need to keep synchronization, which is necessary for keeping hopping synchronized, and other functions like Power Saving. On an infrastructure BSS, this is achieved by all the stations updating their clocks according to the Access Point’s clock, using the following mechanism: The Access Point periodically transmits frames called Beacon Frames. These frames contain the value of the Access Point’s clock at the moment of transmission.
APPENDIX E: IEEE 802.11 Technical Tutorial The WEP is a simple algorithm based on RSA’s RC4 which has the following properties: • Reasonably strong: Brute-force attack to this algorithm is difficult because every frame is sent with an Initialization Vector which restarts the PRNG for each frame. • Self Synchronizing: The algorithm re-synchronizes for each message. This is necessary in order to work in a connectionless environment, where packets may get lost (as any LAN). E.
PRO 11 SERIES WIRELESS ETHERNET NOTE Unicast frames can also be poled by the stations at the DTIM intervals. E.
APPENDIX E: IEEE 802.11 Technical Tutorial • PLCP Signaling Field, which currently contains only the rate information, encoded in 0.5-Mbps increments from 1 Mbps to 4.5 Mbps. • Header Error Check Field, which is a 16-bit CRC error-detection field. E.10.3 MAC DATA The following figure shows the general MAC Frame Format. Part of the fields are only present in part of the frames as described later.
PRO 11 SERIES WIRELESS ETHERNET Type and Subtype These 6 bits define the Type and Subtype of the frame, as indicated in the following table: Type Value b3 b2 00 00 00 00 00 00 00 00 00 00 00 00 00 01 01 01 01 01 01 01 10 10 10 10 10 10 10 10 10 10 138 Type Description Management Management Management Management Management Management Management Management Management Management Management Management Management Control Control Control Control Control Control Control Data Data Data Data Data Data Data Data D
APPENDIX E: IEEE 802.11 Technical Tutorial ToDS This bit is set to 1 when the frame is addressed to the Access Point for forwarding to the Distribution System (including the case where the destination station is in the same BSS, and the Access Point is to relay the frame). The Bit is set to 0 in all other frames. FromDS This bit is set to 1 when the frame is received from the Distribution System.
PRO 11 SERIES WIRELESS ETHERNET Duration/ID This field has two meanings depending on the frame type: • In Power-Save Poll messages, this is the Station ID. • In all other frames, this is the duration value used for the NAV Calculation. Address Fields A frame may contain up to 4 Addresses depending on the ToDS and FromDS bits defined in the Control Field, as follows: • Address-1 is always the Recipient Address (i.e. the BSS station that is the immediate recipient of the packet).
APPENDIX E: IEEE 802.11 Technical Tutorial Sequence Control The Sequence Control Field is used to represent the order of different fragments belonging to the same frame, and to recognize packet duplications. It consists of two subfields, Fragment Number and Sequence Number, which define the frame and the number of the fragment in the frame. CRC The CRC is a 32-bit field containing a 32-bit Cyclic Redundancy Check (CRC) E.11 Most Common Frame Formats E.11.
PRO 11 SERIES WIRELESS ETHERNET E.11.2 CTS FRAME FORMAT The CTS frame looks like this: Octets: 2 Frame Control 2 6 6 4 Duration RA TA CRC MAC Header Figure E-8. CTS Frame. The Receiver Address (RA) of the CTS frame is copied from the Transmitter Address (TA) field of the immediately previous RTS frame to which the CTS is a response.
APPENDIX E: IEEE 802.11 Technical Tutorial E.12 Point Coordination Function (PCF) Beyond the basic Distributed Coordination Function, there is an optional Point Coordination Function, which may be used to implement time-bounded services, like voice or video transmission. This Point Coordination Function makes use of the higher priority that the Access Point may gain by the use of a smaller InterFrame Space (PIFS).
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