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FHSS continuously changes the center frequency of a conventional carrier several times per second according to a pseudo-random set of channels, while chirp spread spectrum changes the carrier frequency. Because a fixed frequency is not used, illegal monitoring of spread spectrum signals is extremely difficult, if not downright impossible depending on the particular method. FHSS is the transmission technology in Bluetooth. See http://www.answers.com/topic/802-11-technology, http://www.answers.com/topic/wi-fi-technology and http://www.answers.com/topic/bluetooth-technology. FHSS continuously changes the center frequency of a conventional carrier several times per second according to a pseudo-random set of channels, while chirp spread spectrum changes the carrier frequency. Because a fixed frequency is not used, illegal monitoring of spread spectrum signals is extremely difficult, if not downright impossible depending on the particular method. FHSS is the transmission technology in Bluetooth. See http://www.answers.com/topic/802-11-technology, http://www.answers.com/topic/wi-fi-technology and http://www.answers.com/topic/bluetooth-technology.
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How can dsss benefits from multipath propagation?
It can't, Prof. Schiller is wrong In contrary DSSS is more vulnerable to multipathing than e.g. FHSS is since it could just ignore its own shadows after jumping.
Name the various types of multiplexing techniques?
Multiplexing techniques vary widely based on what is being multiplexed. Modern telecommunications use a very wide array of techniques including: TDM - examples: TDMA, T-carrier FDM - examples: DWDM Spatial - example: MIMO Code division - examples: CDMA Phase or polarization division - cable/satellite TV Statistcal - examples: packet mode (STS), FHSS etc etc. This is far from a complete list. I think the question needs to be more specific.
What are TCP IP and 802.11?
TCP and IPTCP and IP were developed by a Department of Defense (DOD) research project to connect a number different networks designed by different vendors into a network of networks (the "Internet").It was initially successful because it delivered a few basic services that everyone needs (file transfer, electronic mail, remote logon) across a very large number of client and server systems. Several computers in a small department can use TCP/IP (along with other protocols) on a single LAN. The IP component provides routing from the department to the enterprise network, then to regional networks, and finally to the global Internet. On the battlefield a communications network will sustain damage, so the DOD designed TCP/IP to be robust and automatically recover from any node or phone line failure. This design allows the construction of very large networks with less central management. However, because of the automatic recovery, network problems can go undiagnosed and uncorrected for long periods of time.As with all other communications protocol, TCP/IP is composed of layers:IP - is responsible for moving packet of data from node to node. IP forwards each packet based on a four byte destination address (the IP number). The Internet authorities assign ranges of numbers to different organizations. The organizations assign groups of their numbers to departments. IP operates on gateway machines that move data from department to organization to region and then around the world.TCP - is responsible for verifying the correct delivery of data from client to server. Data can be lost in the intermediate network. TCP adds support to detect errors or lost data and to trigger retransmission until the data is correctly and completely received.TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet). 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.TCP/IP is a two-layer program. The higher layer, Transmission Control Protocol, manages the assembling of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets into the original message. The lower layer, Internet Protocol, handles the address part of each packet so that it gets to the right destination. Each gateway computer on the network checks this address to see where to forward the message. Even though some packets from the same message are routed differently than others, they'll be reassembled at the destination.TCP/IP uses the client/server model of communication in which a computer user (a client) requests and is provided a service (such as sending a Web page) by another computer (a server) in the network. TCP/IP communication is primarily point-to-point, meaning each communication is from one point (or host computer) in the network to another point or host computer. TCP/IP and the higher-level applications that use it are collectively said to be "stateless" because each client request is considered a new request unrelated to any previous one (unlike ordinary phone conversations that require a dedicated connection for the call duration). Being stateless frees network paths so that everyone can use them continuously. (Note that the TCP layer itself is not stateless as far as any one message is concerned. Its connection remains in place until all packets in a message have been received.)Many Internet users are familiar with the even higher layer application protocols that use TCP/IP to get to the Internet. These include the World Wide Web's Hypertext Transfer Protocol (HTTP), the File Transfer Protocol (FTP), Telnet (Telnet) which lets you logon to remote computers, and the Simple Mail Transfer Protocol (SMTP). These and other protocols are often packaged together with TCP/IP as a "suite."802.11802.11 and 802.11x refers to a family of specifications developed by the IEEEforwireless LAN (WLAN) technology. 802.11 specifies an over-the-air interface between a wireless client and a base station or between two wireless clients. The IEEE accepted the specification in 1997.There are several specifications in the 802.11 family:· 802.11 - applies to wireless LANs and provides 1 or 2 Mbps transmission in the 2.4 GHz band using either frequency hopping spread spectrum (FHSS) or direct sequence spread spectrum (DSSS).· 802.11a - an extension to 802.11 that applies to wireless LANs and provides up to 54-Mbps in the 5GHz band. 802.11a uses an orthogonal frequency division multiplexing encoding scheme rather than FHSS or DSSS.· 802.11b (also referred to as 802.11 High Rate or Wi-Fi) - an extension to 802.11 that applies to wireless LANS and provides 11 Mbps transmission (with a fallback to 5.5, 2 and 1-Mbps) in the 2.4 GHz band. 802.11b uses onlyDSSS. 802.11b was a 1999 ratification to the original 802.11 standard, allowing wireless functionality comparable to Ethernet.· 802.11e - a wireless draft standard that defines the Quality ofService (QoS) support for LANs, and is an enhancement to the 802.11a and 802.11b wireless LAN (WLAN) specifications. 802.11e adds QoS features and multimedia support to the existing IEEE 802.11b and IEEE 802.11a wireless standards, while maintaining full backward compatibility with these standards.· 802.11g - applies to wireless LANs and is used for transmission over short distances at up to 54-Mbps in the 2.4 GHz bands.· 802.11n - 802.11n builds upon previous 802.11 standards by addingmultiple-inputmultiple-output (MIMO). The additional transmitter and receiver antennas allow for increased data throughput through spatial multiplexing and increased range by exploiting the spatial diversity through coding schemes like Alamouti coding. The real speed would be 100 Mbit/s (even 250 Mbit/s in PHY level), and so up to 4-5 times faster than 802.11g.· 802.11r - 802.11r, also called FastBasic ServiceSet (BSS) Transition, supports VoWi-Fi handoff between access points to enable VoIP roaming on a Wi-Fi network with 802.1X authentication.· 802.1X - Not to be confused with 802.11x (which is the term used to describe the family of 802.11 standards) 802.1X is an IEEE standard for port-based Network Access Control that allows network administrators to restricted use of IEEE 802 LAN service access points to secure communication between authenticated and authorized devices.What Is 802.11 Wireless?The wireless local area network (WLAN) protocol, IEEE 802.11, and associated technologies, such as the 802.1X protocol and Wi-Fi Protected Access (WPA), allow secure high-speed wireless network access and mobile access to a network infrastructure. Until the recent development and wide adoption of IEEE 802.11b, also known as Wi-Fi, in order to obtain high-speed network access to your local area network (LAN) your network client needed to be physically connected to the LAN with some type of wiring. Benefits· Some of the specific benefits of implementing a WLAN are included in the following:· Wireless connections can extend or replace a wired infrastructure· Increased productivity for the mobile employee· Dependencies for a secure WLAN802.11 Wireless Network InfrastructureThe following figure shows a simple example of a WLAN using a wireless access point and some of the Windows Server 2003 technologies on which a secure WLAN is dependent.Below is shown a Wireless Network Infrastructure
What is the difference between slow and fast FHSS?
The difference between slow and fast FHSS is the speed of the transmitting radio signals. Both have signals that are difficult to intercept.
What must the FHSS transmitting and receiving units know to communicate?
The hopping sequence.
Working of frequency hopping spread spectrum?
exlanation of fhss block diadram
What is the signaling method used by Bluetooth?
FHSS(Frequency Hopping Spread Spectrum)
When was the concept used by FHSS technology developed?
during World War II
Is 802.11g mobile wireless networking standard that uses FHSS RF signaling in the 2.4 GHz band?
No
What encoding or modulation technology does 802.11 use?
FHSS- Which has been dropped recently DSSS- which is still used by access points to advertise themselves
Spread spectrum techniques fhss and dsss?
"Direct Sequence Spread Spectrum (DSSS)DSSS multiplies the data bits by a very fast pseudo-random bit pattern (PN sequence) that "spreads" the data into a large coded stream that takes the full bandwidth of the channel. DSSS is the basis for CDMA cellphones and 802.11 Wi-Fi wireless transmission. For a technical example of DSSS technology, see cdma.Frequency Hopping Spread Spectrum (FHSS)FHSS continuously changes the center frequency of a conventional carrier several times per second according to a pseudo-random set of channels, while chirp spread spectrum changes the carrier frequency. Because a fixed frequency is not used, illegal monitoring of spread spectrum signals is extremely difficult, if not downright impossible depending on the particular method. FHSS is the transmission technology in Bluetooth. See integrated-business-systems-and-services-inc, wifiand bluetooth."From spread-spectrum
Can you describe the fhss and dsss spread spectrum technologies?
"Direct Sequence Spread Spectrum (DSSS)DSSS multiplies the data bits by a very fast pseudo-random bit pattern (PN sequence) that "spreads" the data into a large coded stream that takes the full bandwidth of the channel. DSSS is the basis for CDMA cellphones and 802.11 Wi-Fi wireless transmission. For a technical example of DSSS technology, see cdma.Frequency Hopping Spread Spectrum (FHSS)FHSS continuously changes the center frequency of a conventional carrier several times per second according to a pseudo-random set of channels, while chirp spread spectrum changes the carrier frequency. Because a fixed frequency is not used, illegal monitoring of spread spectrum signals is extremely difficult, if not downright impossible depending on the particular method. FHSS is the transmission technology in Bluetooth. See integrated-business-systems-and-services-inc, wifiand bluetooth."From spread-spectrum
How can dsss benefits from multipath propagation?
It can't, Prof. Schiller is wrong In contrary DSSS is more vulnerable to multipathing than e.g. FHSS is since it could just ignore its own shadows after jumping.
What are the Four primary technologies in which wireless lans uses in transmitting and receiving data?
a. Direct sequence spread spectrum (DSSS). b. Frequency hopping spread spectrum (FHSS). c. Infrared d. Orthogonal frequency division multiplexing(OFDM)
Do the Panasonic digital cordless phone systems include answering machines, or do I have to purchase one separately?
Yes, there are many panasonic digital cordless phone systems that include answering machines. The "Panasonic KX-TG3032B 2.4GHz FHSS, Caller Waiting, Caller ID, Digital Answering Machine Cordless Telephone" includes an answering machine. It can be purchased at "wegotbetterdeals.com." you have to purchase one seperately.
