ofdm modulation

: 1) the VDSL frequency is 1.1 ~ 20 MHz, above the ADSL frequency band. VDSL uses OFDM for communication, that is, the uplink and downlink use different frequency ranges. The following is an example of the common spectrum distribution ~ 3.4 MHz; upstream 4.0 ~ 7.75 MHz. Other frequently-used low-frequency services, such as ISDN, common telephone, and ADSL, can be transmitted online with VDSL at the same time. Generally, the center frequency and bandwi

support more than 60 enterprise users or hundreds of home users who use E1/T1 at the same time. WiMAX uses a variety of advanced technologies, such as OFDM, diversity, and adaptive modulation, to achieve NLOS and block line of sight ONLOS transmission, effectively improving the efficiency of wireless transmission in the city. The physical layer supports TDD/DMTA and FDD/TDMA radio duplex multiplexing modes

can use more than four channels in the same coaxial cable branch distribution network. Each channel can provide users with 80 Mbps of shared bandwidth. With hinoc technology, the network structure of existing users can be easily changed, and multiple business applications, including high-speed Internet access, Hd/standard, broadcast, IPTV, VOD, and VoIP, can be carried. 5. technical features and application analysis (1) technical features, hinoc technology, the same coaxial cable can accom

International standard update and improve, Further standardizing the development and application of products with different frequency points and higher network rate products, in addition to the content of original IEEE802.11, the Management Information Base (MIB) based on SNMP (Simple Network Management Protocol) protocol is added to replace the management information base of the original OSI protocol. In addition, high-speed network content has been added. IEEE802.11 points ieee802.11a and iee

The expands the standard physical layer, requiring the layer to use a 5GHz band. The standard adopts OFDM modulation technology, there are "12" non-overlapping transmission channels, the transmission rate range is 6mbps-54mbps. However, this standard is incompatible with the IEEE802.11B standard. Wireless APs and wireless cards that support the protocol are less common in the marketplace. ieee802.11g

reach 300 meters. Currently, 802.11b is also called Wi-Fi. Evaluation: the implementation of such standards was earlier. Currently, many wireless products on the market only support this protocol. A significant feature of such products is the "high quality and low price". Although the supported speed can only reach 11 Mbps, its affordable price can greatly lower the threshold for users of wireless networks. This type of product is already a transitional "product ". 2. IEEE802.11a protocol This

grouping data unit and the PHY layer data unit of the 802.16 protocol. The physical layer uses forward correction encoding (FEC), symbol ing, OFDM modulation, and other technologies to prepare wireless air connections for data units. The radio transceiver sends signals to the SS or BS through an antenna. After the SS and BS receive signals, the signal is restored to the desired audio and video content thro

turn from: http://blog.csdn.net/myarrow/article/details/7930131 1. IE802.11 Introduction Standard number IEEE 802.11b IEEE 802.11a IEEE 802.11g IEEE 802.11n Standard release Time September 1999 September 1999 June 2003 September 2009 Working frequency range 2.4-2.4835ghz 5.150-5.350ghz 5.475-5.725ghz 5.725-5.850ghz 2.4-2.4835ghz 2.4-2.4835ghz 5.150-5.850ghz Number of non-overlapping channels 3

: physical layer, data link layer, network layer, transport layer, Session Layer, presentation layer, and application layer. TCP/IP layer-4 Protocol: network interface layer, Internet layer IP, transport layer, and application layer. Five-Layer Protocol: physical layer, data link layer, network layer, transport layer, and application layer. Chapter 2 Physical Layer Main tasks of the physical layer: determine the characteristics related to the interface of the transmission media, that is, mechani

system, proposing many techniques to meet these requirements: WCDMA, OFDM, TDSCDMA and ODMA. Technical entities of the third generation Partner Project (3GPP) are assigned to analyze these proposed technologies. The result of this work is that WCDMA has become the most preferred technology for 3G systems. 3GPP has written a technical specification, 25.101 of which includes the core performance requirements of the RF hardware part of the WCDMA mobile

. RF chip in the use of OFDM modulation mode to send data, the entire frame is divided into different data blocks to send, in order to ensure the reliability of data transmission, there will be a GI between the blocks, so that the receiving side can correctly parse out the various data blocks. Wireless signal in the space transmission due to multipath and other factors on the receiving side of the formation

-power modes such as sleep mode with RTC, requiring less than 4μa of current. Features: Cc3200 simplelink Wi-Fi-consists of application microcontroller, Wi-Fi network processor and Power Management Subsystem Application microcontroller Subsystem Arm Cortex-M4 kernel, operating at 80 MHz Embedded Memory Ram (up to 256kb) External serial FLASH Boot Loader and peripheral drivers in ROM 32-channel Direct Memory Access (DMA) A hardware encryption engine for advan

transmission channel to the MAC layer. The MAC layer provides different logical channels for the wireless link control RLC sub-layer of Layer 2. Figure 1 wireless interface protocol structure around the physical layer Physical Layer Functions The physical layer provides data transmission services to senior management through transmission channels. The physical layer provides the following functions: 1) The error detection of the transmission channel and provides instructions to the senior ma

Transferred from: http://blog.csdn.net/myarrow/article/details/79301311. IE802.11 Introduction Standard number IEEE 802.11b IEEE 802.11a IEEE 802.11g IEEE 802.11n Standard release Time September 1999 September 1999 June 2003 September 2009 Operating frequency range 2.4-2.4835ghz 5.150-5.350ghz5.475-5.725ghz5.725-5.850ghz 2.4-2.4835ghz 2.4-2.4835ghz5.150-5.850ghz Number of non-overl

/n) = 3 K * log2 (1 + 1030/10) Therefore, the number of BITs that can be sent per second cannot exceed 30 kbps.5. 8 phasesAnd the first phase has two ways of PAM modulation. 1200baud Signal TransmissionData that can be achieved at a specific rate Transmission RateWhat is it? My answer is: S = B · log2n = Export xlog2 8 = 3600bps 6. The Pam modulation method with two amplitude values for each phase is used t

100 meters, outdoor can reach 300 meters. Currently also known as 802.11b Wi-Fi. Analysis: This kind of standard implementation time is earlier, currently on the market still many wireless products only support to this Agreement standard scope. This type of product is characterized by "inexpensive", although the speed of support can only reach 11Mbps, but its affordable price for the initial wireless network users to reduce the threshold. Such products are already part of the transition "produc

separates the high frequency from the current and transmits it to a computer or phone, to transfer information. On the basis of no re-wiring, this technology can carry data, voice, video, and other services on existing wires, that is, to achieve the integration of four networks. End users can connect to the Internet by plugging in the power plug. PLC uses the range of m to 30 m to transmit signals. During transmission, the user data is modulated using GMSK or

venues. This is especially suitable for future application in Olympic Games, wiMAX features shorter deployment cycles and greater flexibility than DSL or Cable access. Point-to-Point Wireless Broadband Access Point-to-Point wireless broadband access is mainly used for point-to-point wireless backhaul and relay services. Point-to-Point wireless broadband access not only greatly extends the WiMAX network coverage, but also provides wireless relay transmission for the carrier's 2G/3G network base

wide instantaneous bandwidth while ensuring efficient mirror-frequency rejection and minimizing lo leakage. Mirror frequency rejection and lo leakage performance can be achieved with wideband quadrature correction, the receiver path is optimized and can be used as a vector signal analyzer for wideband demodulationLow if mode and in-band re-adjustmentThe low if receiver is another type of receiver using the IQ demodulator with the same block diagram as the 0 if receiver shown in Figure 5. In a 0

WiMAX can be considered as an alternative to some DSL or cable access modes; For some temporary gatherings, such as exhibitions and sports venues, WiMAX has the flexibility to deploy quickly, which is especially suitable for future applications in Olympic projects, and the WiMAX deployment cycle features a shorter and more flexible approach than DSL or cable access. Point to point Wireless broadband access Point-to-Point wireless broadband access is mainly used in point-to-point mode for wire