orthogonal frequency division multiple access

... several common technologies with subtle differences.The main common technology is orthogonal frequency- division multiple access (OFDMA) - There are many good reasons for choosing OFDMA such as multipath ... bandwidths, the ability to handle different data rates, and the ability to easily combine with multiple antenna techniques Nhóm - The focus of this article is on the comparative use of OFDMA ... WIMAX AND LTE RESOURCE MAPPING FROM SUBCARRIERS Subcarriers are the smallest granular units in the frequency domain, OFDM symbol duration is the smallest granular unit in the time domain in OFDMA...

Ngày tải lên: 24/07/2015, 22:26

Ngày tải lên: 24/07/2015, 22:27

... Typical OFDM-based multiple access techniques include Time Division Multiple Access (OFDM-TDMA), Code Division Multiple Access (OFDM-CDMA or MC-CDMA) and Frequency Division Multiple Access (OFDM-FDMA) ... division multiple access MSE mean square error CFO carrier frequency offset OFDM orthogonal frequency division multiplexing CP cyclic prefix OFDMA orthogonal frequency division multiple access CRLB ... communications, Orthogonal Frequency Division Multiplex (OFDM) is widely accepted as a major technique for many future broadband wireless systems OFDMA, a multiuser OFDM using Frequency Division Multiple Access...

Ngày tải lên: 14/09/2015, 14:03

... keying (QPSK) Sophisticated multiple access technology like frequency division multiple access (FDMA), time division multiple access (TDMA) and code division multiple access (CDMA) also gained ... systems, multiple access technologies based on orthogonal frequency division multiplexing (OFDM) air interface were chosen [8] In the downlink, the popular orthogonal frequency division multiple access ... Code Division Multiple Access DFT Discrete Fourier Transform FDE Frequency Domain Equalizer FDMA Frequency Division Multiple Access FEC Forward Error Correcting FFT Fast Fourier Transform FH Frequency...

Ngày tải lên: 08/09/2015, 18:24

... power loading Multiple access The resources available in a CR system must be shared among the radios OFDM supports several multiple access techniques In Frequency Division Multiple Access (FDMA), ... and TDMA, a combinatorial multiple access scheme was invented for OFDM systems known as orthogonal frequency division multiple access (OFDMA) OFDMA partitions both frequency and time dimensions, ... access control MBLP Mixed binary linear programming ACRONYMS xiv MINLP Mixed integer nonlinear programming MS Mobile station OFDM Orthogonal frequency division multiplexing OFDMA Orthogonal frequency...

Ngày tải lên: 09/09/2015, 10:19

... European Telecommunication Standard Institute fc frequency carrier FDM Frequency Division Multiplexing FDMA Frequency Division Multiple Access Fd Doppler Frequency FEC Forward Error Correction FFT ... Phase Shift Keying BS Base Station BWA Broadband Wireless Access CDMA Code Division Multiple Access COFDM Coded Orthogonal Frequency Division Multiplexing CPE Customer-premises equipment d2(y,z) squared ... Cellular (PDC), Code Division Multiple Access (CDMA-2000), Wideband Code Division Multiple Access/ Universal Mobile Telecommunications System (WCDMA/UMTS), High Speed Downlink Packet Access (HSDPA),...

Ngày tải lên: 26/05/2013, 21:28

... 2002 [4] L J Cimini Jr., “Analysis and simulation of a digital mobile channel using orthogonal frequency division multiplexing,” IEEE Transactions on Communications, vol 33, no 7, pp 665– 675, 1985 ... IEEE P802.15-03/268r2, November 2003 [6] B L Floch, M Alard, and C Berrou, “Coded orthogonal frequency division multiplex,” Proceedings of the IEEE, vol 83, no 6, pp 982–996, 1995 [7] G Ungerboeck, ... parameters of the model, and p is the order of the model Based on the frequency- domain measurements in the 4.3 GHz to 5.6 GHz frequency band, a second-order (p = 2) AR model is reported to be sufficient...

Ngày tải lên: 22/06/2014, 22:20

... cases with multiple users, that is, there is virtually no loss in power efficiency compared to the case without MAI We therefore obtain a quasiorthogonal multiple access without the need for orthogonal ... spread-spectrum multiple- access channels,” IEEE Journal on Selected Areas in Communications, vol 8, no 4, pp 641–649, 1990 [7] P A Hoeher and H Schoeneich, “Interleave -division multiple access from ... downlink multiple access capacity for Beyond 3G,” IEEE Communications Magazine, vol 43, no 1, pp 61–69, 2005 [10] J C Fricke, H Schoeneich, and P A Hoeher, “An interleavedivision multiple access...

Ngày tải lên: 22/06/2014, 23:20

... of multiple- access system with multiple antennas at the base station Most previous studies are constrained to either fixed channel condition [11, 12] or ergodic capacity region [13] The space -division ... maximize the sum capacity of a time invariant Gaussian MIMO multiple- access channel The ergodic capacity region for MIMO multiple- access channel with covariance feedback has been studied in [13] ... with multiple antennas,” IEEE Transactions on Information Theory, vol 47, no 4, pp 1273–1289, 2001 [11] B Suard, G Xu, H Liu, and T Kailath, “Uplink channel capacity of space -division- multiple- access...

Ngày tải lên: 23/06/2014, 01:20

... understood orthogonal access techniques such as time division multiple access and frequency division multiple access Additionally, random access schemes such as carrier sense multiple access are ... Techniques for Code Division Multiple Access 23 2.1 Forms of Code Division Multiple Access 23 2.2 Direct Sequence Code Division Multiple Access ... contention-free multiple access is in how the channels are defined In time division multiple access (TDMA), channels are defined according to time slots In frequency division multiple access (FDMA),...

Ngày tải lên: 27/06/2014, 14:20

... Minimum Carrier Spacing Frequency Digital televsion techniques – Lecture 2013 17 17 COFDM Orthogonal carriers Digital televsion techniques – Lecture 2013 18 18 COFDM Orthogonal carriers Digital ... MHz • Developed for MHz channels – A MHz variant has been produced and tested • Can use single frequency networks - SFNs • New technology with scope for continued improvement & development Digital ... amplitude Digital televsion techniques – Lecture 2013 12 12 …Mathematical description of COFDM Zeroth frequency = gives Compare with IFT Equivalent if Digital televsion techniques – Lecture 2013 13...

Ngày tải lên: 09/07/2014, 08:16

... Signal processing made digitally in the frequency domain – IFFT/FFT –pair • Guard time is added to reduce effects caused by multipath propagation • Tolerant to frequency- selective fading – Information ... to frequency and phase offset errors – Peak to average power - problem Kari Pietikäinen Communications Laboratory / HUT S-72.333 Postgraduate Course in Radio Communications Subchannels • Frequency- selective ... IFFT / FFT pair is the key factor in OFDM – IFFT: From frequency domain to time domain – FFT: Vice versa • All signal processing is made in frequency domain • IFFT / FFT low implementation cost...

Ngày tải lên: 11/07/2014, 20:21

Ngày tải lên: 25/07/2014, 09:39

... understood orthogonal access techniques such as time division multiple access and frequency division multiple access Additionally, random access schemes such as carrier sense multiple access are ... Techniques for Code Division Multiple Access 23 2.1 Forms of Code Division Multiple Access 23 2.2 Direct Sequence Code Division Multiple Access ... contention-free multiple access is in how the channels are defined In time division multiple access (TDMA), channels are defined according to time slots In frequency division multiple access (FDMA),...

Ngày tải lên: 07/08/2014, 21:20

... Techniques for Code Division Multiple Access In the previous chapter, we reviewed the basic concepts of multiuser communications and the multiple access techniques used to allow multiple users to ... IML September 28, 2006 15:54 CODE DIVISION MULTIPLE ACCESS (CDMA) 1.2.1 ALOHA The most common contention-based methods are random access methods The first random access method was developed by Abramson ... application to ultra-wideband (UWB) systems 2.1 FORMS OF CODE DIVISION MULTIPLE ACCESS CDMA is also known as spread spectrum multiple access or SSMA because the use of spread spectrum waveforms...

Ngày tải lên: 07/08/2014, 21:20

... 28, 2006 15:54 CODE DIVISION MULTIPLE ACCESS (CDMA) FIGURE 2.4: Comparison of original/despread signal and spread signal spectra for DS/SS with square pulses 2.2.2 Multiple Access The DS/SS technique ... MOBK023-Buehrer.cls September 28, 2006 15:54 CODE DIVISION MULTIPLE ACCESS (CDMA) Frequency 38 BS B Ts Tc Tb Time FIGURE 2.10: Example of a time frequency plot for slow hopping (Tc : hop period, ... September 28, 2006 15:54 SPREAD SPECTRUM TECHNIQUES FOR CODE DIVISION MULTIPLE ACCESS 41 If we choose the frequency spacing to be an integer multiple of the hop rate for illustration purposes, we sample...

Ngày tải lên: 07/08/2014, 21:20

... hopping to be incorporated into the coding decision statistics 2.8 MULTIPLE ACCESS PERFORMANCE OF FREQUENCY- HOPPED CODE DIVISION MULTIPLE ACCESS Although the emphasis of this chapter is DS-CDMA, we ... additional channel estimation, which can be substantial 2.6 MULTIPLE ACCESS PERFORMANCE OF DIRECT SEQUENCE CODE DIVISION MULTIPLE ACCESS The previous section examined the performance of a single ... that we have not considered that arise in the multiple cell scenario P2: IML MOBK023-Buehrer.cls September 28, 2006 15:54 CODE DIVISION MULTIPLE ACCESS (CDMA) 10 K=1 K = 10 K = 20 K = 30 K =...

Ngày tải lên: 07/08/2014, 21:20

... CODE DIVISION MULTIPLE ACCESS In this section, we will discuss four key principles of CDMA systems, particularly cellular systems: interference averaging, statistical multiplexing, universal frequency ... 28, 2006 15:55 CODE DIVISION MULTIPLE ACCESS (CDMA) 3.1.4 Statistical Multiplexing The final fundamental CDMA concept that we will discuss in this section is termed statistical multiplexing, which ... 28, 2006 15:54 SPREAD SPECTRUM TECHNIQUES FOR CODE DIVISION MULTIPLE ACCESS 69 where P2 is the probability of any two users hopping to the same frequency in the same symbol duration For independent...

Ngày tải lên: 07/08/2014, 21:20

... P1: IML/FFX MOBK023-03 P2: IML MOBK023-Buehrer.cls 88 September 28, 2006 15:55 CODE DIVISION MULTIPLE ACCESS (CDMA) where I0 includes thermal noise power spectral density Including the effect ... IML/FFX MOBK023-03 P2: IML MOBK023-Buehrer.cls September 28, 2006 15:55 CELLULAR CODE DIVISION MULTIPLE ACCESS 89 Sector interference sources rm ro FIGURE 3.7: Illustration of out-of-cell interference ... (3.38) P1: IML/FFX MOBK023-03 P2: IML MOBK023-Buehrer.cls 90 September 28, 2006 15:55 CODE DIVISION MULTIPLE ACCESS (CDMA) In a similar fashion, we can show that var I P dm = · 1− Q 2κ e [σ ln(10)/10]2...

Ngày tải lên: 07/08/2014, 21:20

... ALOHA, CSMA, and busy tone multiple access (BTMA) [43] Note that unlike traditional narrowband random access protocols, channel access strategies for SS/PRNs allow for multiple simultaneous transmissions ... MOBK023-Buehrer.cls 118 September 28, 2006 15:55 CODE DIVISION MULTIPLE ACCESS (CDMA) indicator of the success or failure of packet access since multiple transmissions are possible Simply sensing ... Source Modulation and coding Frequency hopper Frequency dehopper Demodulation decoding Source Modulation and coding Frequency hopper Frequency dehopper Demodulation decoding Frequency dehopper Demodulation...

Ngày tải lên: 07/08/2014, 21:20