ofdm modulation

"slower" sub-channels are then combined into "faster" channels in a multi-worker way. So the rate will be faster than a simple channel.The bandwidth of the working channel in 802.11A is MHZ,OFDM the physical layer to differentiate the spectrum into the operating channel. Each bandwidth 20-mhz channel consists of 52 subcarrier. The sub-carrier asks each other a 0.3125MHz channel number from 26 to 26, of which 4 sub-carriers act as pilot carrier, subca

each channel (8 MHz) is time-division multiplexing transmission, the channels are still transmitted in frequency-division multiplexing mode. 1.2 orthogonal frequency division multiplexing Orthogonal Frequency Division Multiplexing is a multi-carrier digital modulation technique. All OFDM carrier frequencies have equal frequency intervals, which are an integer multiple of the basic oscillation frequencies.

to carry user data, but rather to provide a technical means to allow the terminal to perform downlink channel estimation. The terminal can get downlink CQI,PMI,RI and other information by measuring the specific reference signal of the cell.In each cell, there can be one, 2 or 4 cell-specific reference signals that correspond to 1, 2, or 4 antenna ports respectively. For a cell that supports Pdsch transmission, all of its downstream sub-frames transmit cell-specific reference signals that can be

. Compared with single-carrier technology with the same data rate, OFDM signals have a longer symbol period, this technology has a strong performance against multi-path fading. In addition, the modulation methods used on the carrier are BPSK, PSK, 16QAM, and 64QAM. Various Modulation Algorithms are automatically switched according to the transmission rate require

. Compared with single-carrier technology with the same data rate, OFDM signals have a longer symbol period, this technology has a strong performance against multi-path fading. In addition, the modulation methods used on the carrier are BPSK, PSK, 16QAM, and 64QAM. Various Modulation Algorithms are automatically switched according to the transmission rate require

Frame Structure LTETwo supported wireless frames Type 1: applied to FDD Type 2: Used In TDD FDDWireless Frame Structure The FDD wireless frame length is 10 ms, as shown in. Each frame is divided into 10 sub-frames of the same size. Each sub-frame is divided into two time slots of the same size, that is, each FDD wireless frame contains 20 time slots of the same size, each time slot is 0.5 ms. In a common CP configuration, a time slot contains seven consecutive

sub-carrier are intertwined across all sub-bands. In this way, on the one hand, we make full use of the frequency diversity between the system sub-carrier and sub-band, greatly enhancing the MB-OFDM-UWB system's ability to resist narrow band interference; on the other hand, through orthogonal extension and interweaving of the transmitted data, the data entering the multi-carrier modulation tends to be Gaus

existing communication technologies from a relatively high level and system perspective, and analyzed many seemingly completely unrelated technologies in a unified mathematical expression, in particular, the popular technologies such as MIMO, Opportunistic Communication, OFDM, and multi-user Communication have been interpreted from the viewpoint of information theory, this is helpful for us to grasp the current development direction of wireless commu

1 Multimedia service drives the development of OFDM technology Orthogonal Frequency Division Multiplexing (OFDM) is a multicarrier digital modulation technology whose research history dates back to the mid 1960s, although the concept of OFDM has existed for a long time, but until recently, with the development of mult

wireless access technology, covering only 35m-100m; WiMAX technology, 3G Technology, LMDS Technology, MMDS Technology, trunking communications belong to the metropolitan Area Network access technology, coverage in 1km-54km range, and satellite communications, point-to-point microwave is a WAN technology, usually used for communication backbone network construction. from the transmission rate, point-to-point microwave and satellite communications belong to the main transmission technology, the

SRS during the uppts section of the Special subframe. FDD The uplink FDD frame is the same length as the downlink frame and contains only uplink user transmissions. modulation For uplink data signals (PUSCH), the LTE standard uses single Carrier-frequency division multiple Access (SC-FDMA) modul ation, which have a lower peak-to-average power ratio, meaning lower cost amplifiers and less power usage. In SC-FDMA, the user data was modulated onto a sin

user communicates with a PSTN user, the IAD user accesses the IP bearer network through the WIMAX wireless link, which is controlled by the media gateway controller Huawei SOFT3000) and sends the media stream to the integrated media gateway Huawei UMG8900 ), UMG8900 and PSTN Programmable switch Huawei CC08) have a direct circuit to complete communication. When IAD users perform voice communication, they are controlled by the media gateway controller Huawei SOFT3000) and communicate through the

The development of wireless network technology has always been a topic of our attention. Do we really know about 802.11n technology? Here we will give a detailed description of the IEEE 802.11n technology through technical improvements on the physical layer and the MAC layer to greatly improve the wireless transmission rate, so that the bandwidth is increased from 54Mbps to 300 Mbps. The core of 802.11n-MIMO-OFDM The

Diversity) and Time Diversity TD, Time Diversity) technology. Multi-carrier Orthogonal Frequency Division Multi-Channel OFDM, Orthogonal OFDM) system is transmitted by multi-channel narrowband Orthogonal sub-carrier at the same time. In recent years, it has been applied in some practical scenarios and proved to have good results. The ARO mentioned earlier in this article is time diversity and has been offi

Pcfich first; 2.1.1, the acquisition of CFI information on the Pcfich channel carries about the subframe in the pdcch of the OFDM symbol number is the CFI information; the current CFI value is 1, 2, 3, the encoding type belongs to block code, The protocol specifies 1-4 corresponding encoded 32-bit sequence, the CFI encoding sequence is scrambling (according to Cellid to obtain the corresponding scrambling code initial value), QPSK

Explanation of the Communication Model of the physical layer, and explanation of the Physical Layer Model Introduction As the underlying layer of wireless communication protocols, the physical layer plays a crucial role in communication performance. It can be seen that almost all technical innovations that achieve cross-generation communication systems are basically on the physical layer, the underlying layer of the physical layer is the modulation a

can not meet the growing business needs, so IEEE in 1999 has launched a 802.11b, 802.11a two standards. And at the end of 2001 through the 802.11G Trial hybrid scheme, which can achieve 54Mbps data rates in the 2.4GHz band, and compatible with the 802.11B standard. 802.11b work in 2.4GHz ISM (industrial, technical, medical) band, using direct series spread spectrum and complement keying, can support 5.5Mbps and 11Mbps two kinds of speed, can with the rate of 1Mbps and 2Mbps 802.11 DSSS (direct

accommodate more non-overlapping channels-orthogonal frequency-division multiplexing (OFDM) signal modulation method-Orthogonal Frequency Division multiplexing technologyHigher rate 54Mbps, 20MHz broadband per channelFrequency-5.15-5.35ghz Indoor-5.7-5.8ghz Outdoor802.11G2.4GHzOrthogonal frequency-division multiplexing (OFDM) signal

become a problem to be solved in the communication field. Cognitive Radio (CR) is an intelligent spectrum sharing technology. It can effectively improve the utilization of spectrum resources by making secondary use of the authorized spectrum. It has become a hot topic in the communication field. In the 802.11 Wireless LAN [1], 802.16 MAN [2] and 3G mobile communication networks [3], Cognitive Radio technology has been applied to increase the system capacity, and began to study the application o

Problem:1. Resource particle Re, used (k,l) to identify the coordinates of the time domain in the frequency domain, how to understand. A: K is the number of the sub-carrier of the resource raster, L is the SC-FDMA ordinal in the time slot 2. A RB has n time-domain continuous SC-FDMA symbols and a continuous sub-carrier composition in the frequency domain. What a SC-FDMA symbol refers to. is the number 0 or 1. or a modulator (for example, 8-in modulation