54/108Mbps
Super G Wireless LAN USB Adapter
WL-U357v2
User’s Manual
(Version 1.0)
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This equipment complies with all the requirements of DIRECTIVE 1999/5/CE OF THE EUROPEAN
PARLIAMENT AND THE COUNCIL OF 9 March 1999 on radio equipment and telecommunication
terminal Equipment and the mutual recognition of their conformity (R&TTE)
The R&TTE Directive repeals and replaces in the directive 98/13/EEC (Telecommunications Terminal
Equipment and Satellite Earth Station Equipment) As of April 8,2000.
Safety
This equipment is designed with the utmost care for the safety of those who install and use it. However, special
attention must be paid to the dangers of electric shock and static electricity when working with electrical
equipment. All guidelines of this and of the computer manufacture must therefore be allowed at all times to
ensure the safe use of the equipment.
EU Countries Not Intended for Use
The ETSI version of this device is intended for home and office use in Austria Belgium, Denmark, Finland,
France (with Frequency channel restrictions). Germany, Greece, Ireland, Italy, Luxembourg .The Netherlands,
Portugal, Spain, Sweden and United Kingdom.
The ETSI version of this device is also authorized for use in EFTA member states Iceland, Liechtenstein,
Norway and Switzerland.
Potential restrictive use
France: Only channels 10,11,12 and 13
WEEE regulation
To avoid the potential effects on the environment and human health as a result of the
presence of hazardous substances in electrical and electronic equipment, end users of
electrical and electronic equipment should understand the meaning of the crossed-out
wheeled bin symbol. Do not dispose of WEEE as unsorted municipal waste and have to
collect such WEEE separately.
Revision
User’s Manual for PLANET Wireless USB Adapter
Model: WL-U357v2
Rev: 1.0 (September. 2006)
Part No. EM-WLU357v2
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Contents
1. Introduction ...............................................................................................1
1.1 Features ................................................................................................1
1.2 Application.............................................................................................1
1.3 Specification ..........................................................................................3
1.4 Package Contents .................................................................................4
1.5 Minimum System Requirements............................................................5
1.6 Installation Considerations ....................................................................5
2. Installation Procedure...............................................................................6
2.1 Utility & Driver Installation......................................................................6
2.2 Hardware Installation...........................................................................10
3. Configuration...........................................................................................12
3.1 Link Information...................................................................................12
3.2 Configuration.......................................................................................13
3.3 Advanced.............................................................................................14
3.4 Site Survey..........................................................................................16
3.5 About US .............................................................................................18
4. Glossary...................................................................................................20
5. Troubleshooting ......................................................................................26
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1. Introduction
Complying with the IEEE 802.11g standard, WL-U357v2 provides simple,
reliable, high-speed wireless connectivity for both desktop and laptop users. By
combining two, state-of-the-art technologies - USB 2.0 and Super G -
WL-U357v2 provides up to 108Mbps data rate in 2.4GHz unlicensed ISM band.
Thus makes WL-U357v2 more suitable for multimedia applications which
required more bandwidth
Support of 64, 128 and 152-bit WEP encryption plus WPA (Wi-Fi Protected
Access) high-level encryption prevents your wireless communications from
unauthorized access and ensures secure data transfer. The WL-U357v2 is also
backward compatible with 802.11b Access Points. Easy installation and
Hot-plugging offers full mobility and high availability, making the device a perfect
choice for users who are getting tired of running cables or in constant need of
wireless access.
1.1 Features
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2.4GHz ISM band, unlicensed operation
Wireless connectivity without the hassles and cost of running cables
IEEE 802.11b/g standard compliant
USB 2.0 A-type standard connector, compatible with USB 1.1
Super G mode provides up to 108Mbps data rate
Utilization of Direct Sequence Spread Spectrum plus OFDM
modulation to provide robust, interference-resistant solution in a
multi-user environment
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Support of 64/128/152-bit WEP encryption and WPA (Wi-Fi Protected
Access) high-level encryption
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Support of Ad-Hoc / Infrastructure mode
Support of most popular operating systems including Windows
98SE/ME/2000/XP/Server 2003
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Plug-and -Play installation
1.2 Application
Infrastructure
The major difference between Infrastructure network and Ad-hoc wireless
network is that the former requires an Access point. For old buildings, open
areas, or frequently changing environments, just install the WL-U357v2 on your
desktop or laptop, and thus you can get connected to the wired Ethernet through
a wireless Access Point. SOHO users can then access the Internet and share all
kinds of data with the other wired or wireless clients within the coverage of
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wireless signals. For enterprise users, the installation of multiple Access Points
to enlarge the coverage of wireless signals can provide wireless users with
seamless network access.
The Infrastructure mode is appropriate for enterprise-scale wireless access to a
central database or provides various wireless applications for mobile users.
Infrastructure mode also supports roaming capabilities for mobile users. More
than one BSS can be configured as an Extended Service Set (ESS). The
continuous wireless network connectivity allows users to roam freely within an
ESS. All wireless clients using WL-U357v2 or other IEEE 802.11b compliant
wireless adapters within one ESS must be configured with the same ESS ID and
to use the same radio channel.
Before adopting an ESS with roaming capability, choosing an available radio
channel with less interference is highly recommended. Proper Access Point
positioning combined with a clear radio channel will greatly enhance
performance.
Ad-Hoc
Still complaining about the high price of wireless access points? This mode is
the easiest and cost-effective way to meet your requirements. It enables you to
construct wireless networking in no time without any access point.
Ad-hoc mode is a wireless network type in which a group of computers equipped
with WL-U357v2 or other wireless adapters are connected together to form an
independent wireless LAN. All computers operating in this mode must be
configured to share the same radio channel.
In this scenario, new devices can be quickly added; however, wireless stations
can only communicate with the other peers that belong to the same IBSS
(Independent Basic Service Set).
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General Application
WL-U357v2 offers a fast, reliable, cost-effective solution for wireless access to
the various network scenarios:
1. Remote access to corporate network for information
E-mail, file transfer and terminal service.
2. Difficult-to-wire environments
Historical or old buildings, public occasions, venues and open area
where it is difficult to wire.
3. Frequently changing environments
Factories, Retailers, and Offices that frequently change locations and
rearrange the workplace
4. Temporary network access
Events, exhibitions, construction sites or some important occasions
that require temporary network access.
5. Access to database for mobile workers
Doctors, nurses, retailers, white-collar workers who need access to
database while roaming in the hospital, retail store or office.
6. SOHO (Small Office and Home Office) users
SOHO users who are in need of easy-to-install and wide coverage
networking.
1.3 Specification
Attached Interface
USB 2.0 A-type connector
Operating Frequency /
Channel
2.412~2.462GHz (FCC, Canada) / 11 Channels
2.412~2.472GHz (ETSI, Europe) / 13 Channels
2.412~2.484GHz (TELEC, Japan) / 14 Channels
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Emission type
RF Modulation
RF Output Power
Direct Sequence Spread Spectrum (DSSS) Technology
OFDM with BPSK, QPSK, 16QAM, 64QAM
15dBm
802.11b: 1, 2, 5.5, 11Mbps
Data Rate
802.11g: 6, 9, 12, 18, 24, 36, 48, 54Mbps
Super G: up to 108Mbps
64/128bit WEP
Security
Antenna
WPA-PSK / WPA2-PSK
WPA / WPA2
Internal Patch Antenna
IEEE802.11b:
2Mbps (QPSK): -87dBm
11 Mbps (QPSK): -82dBm
(Typically @PER < 8% packet size 1024 and @25ºC +
5ºC)
IEE802.11g:
54Mbps (64QAM): -66dBm
48Mbps (64QAM): -69dBm
36Mbps (16QAM): -74dBm
24Mbps (16QAM): -78dBm
Sensitivity
18Mbps (QPSK): -82dBm
12Mbps (QPSK): -84dBm
9Mbps (BPSK): -86dBm
6Mbps (BPSK): -88dBm
(Typically @PER < 10% packet size 1024 and @25ºC +
5ºC)
Working Mode
Power Consumption
Compatibility
Infrastructure, Ad-Hoc
Continuous TX: 472mA,
Continuous RX: 290mA
Windows 98SE/ME/2000/XP/Server 2003
1.4 Package Contents
Before installation, please check the items of your package. The package should include
the following items:
• One Wireless USB Adapter
• One USB Cable
• One CD-ROM (Including the Configuration Utility, Driver and User’s
Manual)
• One Quick Installation Guide
If any of the above items is missing, contact your supplier as soon as possible.
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1.5 Minimum System Requirements
Before installation, please check the following requirements with your
equipment.
• Pentium Based (above) IBM-compatible PC system with one vacancy
USB 1.1/2.0 port
• CD-ROM drive
• Windows 98SE/2000/ME/XP and Server 2003
• At least 5MBytes of free disk space for utility and driver installation
1.6 Installation Considerations
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Beware of the walls and ceilings. Each wall or ceiling can reduce your
wireless cover range form 3-90 feet. Properly position your Access
Points, Residential Gateways, and computers so that the number of
walls or ceilings residing between Access Points and clients is
minimized.
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Building materials make a difference – A solid metal door or aluminum
studs may have a negative effect on signal coverage range. Try to
properly position Access Points and computers with wireless adapters
so that there would be less obstacles existing between them.
Keep your wireless LAN devices away from microwaves, cordless
phones and child incubators. It is likely that the latter will cause
interferences to the operation of your wireless LAN devices.
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2. Installation Procedure
Before you proceed with the installation, it is necessary that you have enough
information about the Wireless USB Adapter. Follow the procedure described below in
this chapter to install the USB adapter under Windows 98SE/ME/2000/XP.
2.1 Utility & Driver Installation
The following installation operates under Window XP. The procedure also applies to
Windows 98SE/ME/2000.
Note 1: If you had ever installed the other Wireless Cards before, please
uninstall the existed drivers and utilities first.
Note 2: Please install the configuration utility before insert WL-U357v2 into
the USB port of the computer.
1. Insert Drivers and User’s manual CD to your CD drive, then a welcome web
will appear.
2. Please click the “Utility” hyper link to start install driver and utility. If the web
screen doesn’t appear, please click the “Start” and choose “Run”. When
dialog box appears, enter “E:\Utility\setup.exe”.
3. When this screen appears, please press “Next” to continue.
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4. You can click “Browse” to specify the Destination Folder that you want to
install the utility. Or keep the default setting and click ”Next” to continue.
5. You can change the Program Folder name as you wish or use the default
name to continue. Please click “Next” for next step.
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6. Installation will start copy driver and utility to your OS.
7. When this dialog box appear, please click “Continue Anyway”.
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8. Please click “Finish” to complete the installation.
9. Please click “Finish” to restart your PC
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2.2 Hardware Installation
1. After PC restart. Please select the correct Country Domain in the pull down
list and press “OK” to continue.
2. Please connect WL-U357 to your PC’s USB port. If your PC’s USB interface
is not USB 2.0, Windows will prompt you there is a High-Speed device
connect to non-High-Speed USB hub. Please don’t worry about this and
keep installing.
3. After properly connect the WL-U357 to your PC, Windows will detect
WL-U357 and show you this dialog box. You can see the device name in this
dialog box. If the device name is correct, please press”Next” to the driver
installation.
4. Windows may show you this driver is not passed Windows Logo test, please
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select “Continue Anyway” to continue.
5. After the driver installation complete appears. Please click “Finish”.
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3. Configuration
3.1 Link Information
The default page is as below after you launch the Utility program.
Status: Shows the SSID associated, which can be used to identify the wireless
network.
SSID: Shows current SSID, which must be the same for the wireless client and
AP in order for communication to be established.
Frequency: Shows the current frequency used for wireless network.
Wireless Mode: Shows the current wireless mode used for wireless
communication.
Encryption: Shows the current encryption mode used for wireless network.
Tx Rate: Shows the current data rate used for transmitting.
Channel: Shows the current channel for communication.
Link Quality: Shows the link quality of the 108Mbps Wireless Network USB
Dongle with the Access Point when operating under Infrastructure mode.
Signal Strength: Shows the wireless signal strength of the connection between
the 108Mbps Wireless Network USB Dongle with the Access Point.
Data Rate: Shows the statistics of data transfer, and the calculation is based on
the number of packets transmitted and received.
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3.2 Configuration
This is the page where you can change the basic settings of the Access Point
with the minimum amount of effort to implement a secure wireless network
environment.
SSID: Service Set Identifier, which is a unique name shared among all clients
and nodes in a wireless network. The SSID must be identical for each clients
and nodes in the wireless network.
Wireless Mode: There are two types available for selection
●Infrastructure – To establish wireless communication with LAN and other
wireless clients through the use the Access Points.
●Ad-Hoc – To establish point-to-point wireless communication directly with other
wireless client devices such as wireless network Adapter.
AdHoc Band: When work with Ad-Hoc mode, this device will force to
IEEE802.11b.
Channel: The value of channel that AP will operate in. You can select the
channel range of 1 to 11 for North America (FCC) domain and 1 to 13 for
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European (ETSI) domain and 1 to 14 for Japanese domain.
Power Mode: There are 3 modes to choose.
●Continuous Access Mode (default) – the USB Dongle is constantly operating
with full power and it consumes the most power.
●Maximum Power Save – the USB Dongle consumes the least power and only
operates when there is wireless network activity.
●Power Save – the USB Dongle consumes the moderate level of power.
Preamble: Select Long or Short Preamble type. Preamble is a sequence of bits
transmitted at 1Mbps that allows the PHY circuitry to reach steady-state
demodulation and synchronization of bit clock and frame start. Two different
preambles and headers are defined: the mandatory supported Long Preamble
and header, which interoperates with the 1 Mbit/s and 2 Mbit/s DSSS
specification (as described in IEEE Std 802.11), and an optional Short Preamble
and header (as described in IEEE Std 802.11b). At the receiver, the Preamble
and header are processed to aid in demodulation and delivery of the PSDU. The
Short Preamble and header may be used to minimize overhead and, thus,
maximize the network data throughput. However, the Short Preamble is
supported only from the IEEE 802.11b (High- Rate) standard and not from the
original IEEE 802.11. That means that stations using Short-Preamble cannot
communicate with stations implementing the original version of the protocol.
Click “Apply” for the changes to take effect.
3.3 Advanced
This is the page where you configure advanced settings of your 108Mbps
Wireless Network USB Dongle
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Auth. Mode: 5 options are available: Open System, Share key, Auto,
WPA/WPA2, WPA-PSK/WPA2-PSK and Disable. Select Open System,
Share key or Auto for WEP data encryption feature. If one of the three options
is selected, it is required to configure the following settings from the next
dropping list.
If WPA/WPA2 is selected, configuration is enabled.
Please click the
“configuration”. The below window is pop up. Then, please select the
certificate that user wants to use and enter the server name and login name
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If WPA-PSK/WPA2-PSK is selected, click the configuration button. The
popping window is as the below. Please enter the key.
The following will only be activated to allow for configuration when Open
System, Share Key or Auto is enabled in “Auth. Mode”.
Default Key: select one of the 4 keys to use.
Network Key: choose the encryption way, either in HEX or ASCII formats, and
enter the password in the blank space.
Key Length: select 64 or 128 bits as the length of the keys
Key Format: ASCII or HEX
3.4 Site Survey
This page allows you to enable the Site Survey function to scan for the available
wireless network (wireless clients and Access Points) and establish wireless
communications with one.
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Available Network – displays the wireless networks (wireless clients and
Access Points) that are in your signal range.
Select any one of them to establish communications by simply mouse
double-click or click on the “Connect” button.
Click “Refresh” button to start scanning for available network again.
Profile – You can create and manage the created profiles for Home, offices or
public areas. By double-clicking on one of the created profile, the setting will
adapt to the configuration such as SSID, channel, and WEP settings saved by
that particular profile.
Remove: To remove the selected the profile
Properties: To view and change its settings of the profile.
Add: To add a profile. Then, the following screen would appear.
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3.5 About US
This page displays some information about the 108Mbps Wireless Network USB
Dongle utility, which includes the version numbers for Driver, Firmware and
Utility. When there is new version of software available for upgrade, you will be
able to identify by version numbers.
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4. Glossary
Access Point: An internetworking device that seamlessly connects wired and
wireless networks.
Ad-Hoc: An independent wireless LAN network formed by a group of computers,
each with a network adapter.
AP Client: One of the additional AP operating modes offered by 54Mbps Access
Point, which allows the Access Point to act as an Ethernet-to-Wireless Bridge,
thus a LAN or a single computer station can join a wireless ESS network through
it.
ASCII: American Standard Code for Information Interchange, ASCII, is one of
the two formats that you can use for entering the values for WEP key. It
represents English letters as numbers from 0 to 127.
Authentication Type: Indication of an authentication algorithm which can be
supported by the Access Point:
1. Open System: Open System authentication is the simplest of the available
authentication algorithms. Essentially it is a null authentication algorithm. Any
station that requests authentication with this algorithm may become
authenticated if 802.11 Authentication Type at the recipient station is set to
Open System authentication.
2. Shared Key: Shared Key authentication supports authentication of stations as
either a member of those who knows a shared secret key or a member of those
who does not.
Backbone: The core infrastructure of a network, which transports information
from one central location to another where the information is unloaded into a
local system.
Bandwidth: The transmission capacity of a device, which is calculated by how
much data the device can transmit in a fixed amount of time expressed in bits
per second (bps).
Beacon: A beacon is a packet broadcast by the Access Point to keep the
network synchronized. Included in a beacon are information such as wireless
LAN service area, the AP address, the Broadcast destination addresses, time
stamp, Delivery Traffic Indicator Maps, and the Traffic Indicator Message (TIM).
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Bit: A binary digit, which is either -0 or -1 for value, is the smallest unit for data.
Bridge: An internetworking function that incorporates the lowest 2 layers of the
OSI network protocol model.
Browser: An application program that enables one to read the content and
interact in the World Wide Web or Intranet.
BSS: BSS stands for “Basic Service Set”. It is an Access Point and all the LAN
PCs that associated with it.
Channel: The bandwidth which wireless Radio operates is divided into several
segments, which we call them “Channels”. AP and the client stations that it
associated work in one of the channels.
CSMA/CA: In local area networking, this is the CSMA technique that combines
slotted time -division multiplexing with carrier sense multiple access/collision
detection (CSMA/CD) to avoid having collisions occur a second time. This works
best if the time allocated is short compared to packet length and if the number of
situations is small.
CSMA/CD: Carrier Sense Multiple Access/Collision Detection, which is a LAN
access method used in Ethernet. When a device wants to gain access to the
network, it checks to see if the network is quiet (senses the carrier). If it is not, it
waits a random amount of time before retrying. If the network is quiet and two
devices access the line at exactly the same time, their signals collide. When the
collision is detected, they both back off and wait a random amount of time before
retrying.
DHCP: Dynamic Host Configuration Protocol, which is a protocol that lets
network administrators manage and allocate Internet Protocol (IP) addresses in
a network. Every computer has to have an IP address in order to communicate
with each other in a TCP/IP based infrastructure network. Without DHCP, each
computer must be entered in manually the IP address. DHCP enables the
network administrators to assign the IP from a central location and each
computer receives an IP address upon plugged with the Ethernet cable
everywhere on the network.
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DSSS: Direct Sequence Spread Spectrum. DSSS generates a redundant bit
pattern for each bit to be transmitted. This bit pattern is called a chip (or chipping
code). The longer the chip, the greater the probability that the original data can
be recovered. Even if one or more bits in the chip are damaged during
transmission, statistical techniques embedded in the radio can recover the
original data without the need for retransmission. To an unintended receiver,
DSSS appears as low power wideband noise and is rejected (ignored) by most
narrowband receivers.
Dynamic IP Address: An IP address that is assigned automatically to a client
station in a TCP/IP network by a DHCP server.
Encryption: A security method that uses a specific algorithm to alter the data
transmitted, thus prevent others from knowing the information transmitted.
ESS: ESS stands for “Extended Service Set”. More than one BSS is configured
to become Extended Service Set. LAN mobile users can roam between different
BSSs in an ESS.
ESSID: The unique identifier that identifies the ESS. In infrastructure association,
the stations use the same ESSID as AP’s to get connected.
Ethernet: A popular local area data communications network, originally
developed by Xerox Corp., that accepts transmission from computers and
terminals. Ethernet operates on a 10/100 Mbps base transmission rate, using
a shielded coaxial cable or over shielded twisted pair telephone wire.
Fragmentation: When transmitting a packet over a network medium,
sometimes the packet is broken into several segments, if the size of packet
exceeds that allowed by the network medium.
Fragmentation Threshold: The Fragmentation Threshold defines the number
of bytes used for the fragmentation boundary for directed messages. The
purpose of "Fragmentation Threshold" is to increase the transfer reliability thru
cutting a MAC Service Data Unit (MSDU) into several MAC Protocol Data Units
(MPDU) in smaller size. The RF transmission can not allow to transmit too big
frame size due to the heavy interference caused by the big size of transmission
frame. But if the frame size is too small, it will create the overhead during the
transmission.
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Gateway: a device that interconnects networks with different, incompatible
communication protocols.
HEX: Hexadecimal, HEX, consists of numbers from 0 – 9 and letters from A – F.
IEEE: The Institute of Electrical and Electronics Engineers, which is the largest
technical professional society that promotes the development and application of
electrotechnology and allied sciences for the benefit of humanity, the
advancement of the profession. The IEEE fosters the development of standards
that often become national and international standards.
Infrastructure: An infrastructure network is a wireless network or other small
network in which the wireless network devices are made a part of the network
through the Access Point which connects them to the rest of the network.
ISM Band: The FCC and their counterparts outside of the U.S. have set aside
bandwidth for unlicensed use in the ISM (Industrial, Scientific and Medical) band.
Spectrum in the vicinity of 2.4GHz, in particular, is being made available
worldwide.
MAC Address: Media Access Control Address is a unique hex number
assigned by the manufacturer to any Ethernet networking device, such as a
network adapter, that allows the network to identify it at the hardware level.
Multicasting: Sending data to a group of nodes instead of a single destination.
Multiple Bridge – One of the additional AP operating modes offered by 54Mbps
Access Point, which allows a group of APs that consists of two or more APs to
connect two or more Ethernet networks or Ethernet enabled clients together.
The way that multiple bridge setups is based on the topology of Ad-Hoc mode.
Node: A network junction or connection point, typically a computer or
workstation.
Packet: A unit of data routed between an origin and a destination in a network.
PLCP: Physical layer convergence protocol
PPDU: PLCP protocol data unit
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Preamble Type: During transmission, the PSDU shall be appended to a PLCP
preamble and header to create the PPDU. Two different preambles and headers
are defined as the mandatory supported long preamble and header which
interoperates with the current 1 and 2 Mbit/s DSSS specification as described in
IEEE Std 802.11-1999, and an optional short preamble and header. At the
receiver, the PLCP preamble and header are processed to aid in demodulation
and delivery of the PSDU. The optional short preamble and header is intended
for application where maximum throughput is desired and interoperability with
legacy and non-short-preamble capable equipment is not consideration. That is,
it is expected to be used only in networks of like equipment that can all handle
the optional mode. (IEEE 802.11b standard)
PSDU: PLCP service data unit
Roaming: A LAN mobile user moves around an ESS and enjoys a continuous
connection to an Infrastructure network.
RTS: Request To Send. An RS-232 signal sent from the transmitting station to
the receiving station requesting permission to transmit.
RTS Threshold: Transmitters contending for the medium may not be aware of
each other. RTS/CTS mechanism can solve this “Hidden Node Problem”. If the
packet size is smaller than the preset RTS Threshold size, the RTS/CTS
mechanism will NOT be enabled.
SSID: Service Set Identifier, which is a unique name shared among all clients
and nodes in a wireless network. The SSID must be identical for each clients
and nodes in the wireless network.
Subnet Mask: The method used for splitting IP networks into a series of
sub-groups, or subnets. The mask is a binary pattern that is matched up with the
IP address to turn part of the host ID address field into a field for subnets.
TCP/IP: Transmission Control Protocol/ Internet Protocol. The basic
communication language or protocol of the Internet. It can also be used as a
communications protocol in a private network, i.e. intranet or internet. When you
are set up with direct access to the Internet, your computer is provided with a
copy of the TCP/IP program just as every other computer that you may send
messages to or get information from also has a copy of TCP/IP.
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Throughput: The amount of data transferred successfully from one point to
another in a given period of time.
WEP: Wired Equivalent Privacy (WEP) is an encryption scheme used to protect
wireless data communication. To enable the icon will prevent other stations
without the same WEP key from linking with the AP.
Wireless Bridge – One of the additional AP operating modes offered by
54mpbs Access Point, which allows a pair of APs to act as the bridge that
connects two Ethernet networks or Ethernet enabled clients together.
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5. Troubleshooting
This section provides solutions to problems usually encountered during the
installation and operation of the USB adapter. Read the description below to
diffuse your doubts.
What is the IEEE 802.11g standard?
802.11g is the latest IEEE standard for high-speed WLAN communications
that provides up to 54Mbps data rate in the 2.4GHZ band. It has become the
mainstream technology of current WLAN networks. It uses OFDM
modulation to reach higher data transmission rate and backward compatible
with 802.11b
What is the IEEE 802.11b standard?
The IEEE 802.11b WLAN standard subcommittee, which formulates a
standard for the industry. The objective is to enable WLAN hardware from
different manufacturers to interoperate.
What features does the IEEE 802.11 standard provide?
The product supports the following IEEE 802.11 functions:
‧ CSMA/CA plus Acknowledge protocol
‧ Multi-Channel Roaming
‧ Automatic Rate Selection
‧ RTS/CTS feature
‧ Fragmentation
‧ Power Management
What is Ad-hoc?
An Ad-hoc mode is a wireless network type in which a group of computers
equipped with wireless adapters are connected as an independent wireless
LAN without any access point. All computers operating in this mode must be
configured to share the same radio channel and SSID.
What is Infrastructure?
The difference between Infrastructure network and Ad-hoc network is that
the former requires an Access point. The Infrastructure mode is appropriate
for enterprise-scale wireless access to a central database or provides various
wireless applications for mobile users.
What is BSS ID?
An Infrastructure network is called a Basic Service Set (BSS). All the
wireless stations in a BSS must share the same BSS ID.
What is TKIP?
It is another encryption method to overcome the inherent weaknesses of
WEP, a next generation of WEP. It adopts new algorithm (Michael) to
generate 128/192-bit encryption keys and provides per-packet key mixing, a
message integrity check and a re-keying mechanism.
What is AES?
AES (Advanced Encryption Standard) is a chip-based encryption method of
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new generation and has been incorporated into the newly-approved security
standard 802.11i. It supports 128, 192 and 256-bit encryption key length and
adopts Rijndael algorithm. It is widely believed it is impossible to crack
AES.
What is DSSS? What is FHSS? And what are their differences?
Frequency-hopping spread-spectrum (FHSS) uses a narrowband carrier that
changes frequency in a pattern that is known to both transmitters and
receivers. Properly synchronized, the net effect is to maintain a single logical
channel. To an unintended receiver, FHSS appears to be short-duration
impulse noise. Direct-sequence spread-spectrum (DSSS) generates a
redundant bit pattern for each bit to be transmitted. This bit pattern is called a
chip (or chipping code). The longer the chip is, the greater the probability
that the original data can be recovered. Even if one or more bits in the chip
are damaged during transmission, statistical techniques embedded in the
radio can recover the original data without-the need for retransmission. To an
unintended receiver, DSSS appears as low power wideband noise and is
rejected (ignored) by most narrowband receivers.
What is Spread Spectrum?
Spread Spectrum technology is a wideband radio frequency technique
developed by the military for use in reliable, secure, mission-critical
communication systems. It is designed to trade off bandwidth efficiency for
reliability, integrity, and security. In other words, more bandwidth is
consumed than in the case of narrowband transmission, but the trade off
produces a signal that is, in effect, louder and thus easier to detect, provided
that the receiver knows the parameters of the spread-spectrum signal being
broadcast. If a receiver is not tuned to the right frequency, a
spread –spectrum signal looks like background noise. There are two main
alternatives, Direct Sequence Spread Spectrum (DSSS) and Frequency
Hopping Spread Spectrum (FHSS).
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