direct sequence spread spectrum systems

... and Spread Spectrum Systems K Fazel Marconi Communications GmbH Germany and S Kaiser German Aerospace Center (DLR) Germany Multi-Carrier and Spread Spectrum Systems Multi-Carrier and Spread Spectrum ... 1.3 Spread Spectrum Techniques 1.3.1 Direct Sequence Code Division Multiple Access 1.3.2 Advantages and Drawbacks of DS-CDMA 1.3.3 Applications of Spread Spectrum 1.4 Multi-Carrier Spread Spectrum ... multi-carrier, spread spectrum and multi-carrier spread spectrum systems We hope that this book will contribute to a better understanding of the principles of multi-carrier and spread spectrum and...

Ngày tải lên: 02/03/2013, 16:58

... s p (t) is called a direct- sequence (DS) spreadspectrum signal The despreading operation is accomplished by multiplying s p (t) by a synchronous version of the spreading sequence: = x(t) · b(t), ... the sequence length, N The chip rate was 0.5 Mchip/s In the referred conditions, the aliasing begins at a sequence period length around 250 New PN Even Balanced Sequences For Spread- Spectrum Systems ... binary sequences for spread spectrum multiplexing (Corresp.),” IEEE Trans Inform Theory, vol 13, no 4, pp 619–621, 1967 [18] R C Dixon, “Gold code sequence generators (see Appendix 7),” in Spread Spectrum...

Ngày tải lên: 23/06/2014, 00:20

... generates a random sequence of 1’s and −1’s The generated binary sequence is spread by a pseudorandom m -sequence by multiplying each information bit by this sequence in the DS spreading block Next, ... described model were run with the following parameters: the spreading factor/processing gain of the spread spectrum system was g p = 127 and the spread signal was oversampled by The filter bank was an ... techniques in spread spectrum communications,” Proceedings of the IEEE, vol 76, no 6, pp 657–671, 1988 [3] F Hsu and A Giordano, “Digital whitening techniques for improving spread spectrum communications...

Ngày tải lên: 23/06/2014, 01:20

... wideband spread spectrum cellular system,” July 1993 [44] TIA/EIA/IS-cdma2000, “Physical layer standard for cdma2000 spread spectrum systems, ” Aug 1999 [45] Turin G.L., “Introduction to spread- spectrum ... Bs before spreading Signal bandwidth B after spreading Frequency Figure 1-9 Power spectral density after direct sequence spreading There are many application fields for spreading the spectrum [13]: ... 1-4 1.3 Spread Spectrum Techniques Spread spectrum systems have been developed since the mid-1950s The initial applications have been military antijamming tactical communications, guidance systems, ...

Ngày tải lên: 09/08/2014, 19:22

... PN spread spectrum systems, ” IEEE, Transactions on Communications, vol 30, pp 913–924, May 1982 [31] Kondo S and Milstein L.B., “On the use of multicarrier direct sequence spread spectrum systems, ” ... before spreading the data symbols on each sub-channel with a userspecific spreading code in time direction, which corresponds to direct sequence spreading on each sub-channel The same spreading ... Two-Dimensional Spreading Spreading in MC-CDMA systems can be carried out in frequency direction, time direction or two-dimensional in time and frequency direction An MC-CDMA system with spreading...

Ngày tải lên: 09/08/2014, 19:22

... With multi-carrier direct sequence spread spectrum, each data symbol is spread over L multi-carrier symbols, each of duration Ts The complex-valued sequence obtained after spreading is given ... asynchronism Figure 2-24 shows the generation of a multi-carrier direct sequence spread spectrum (k) signal The data symbol rate is 1/Td A sequence of Nc complex-valued data symbols dn , n = 0, ... (L d0 − 1) 0 spreader c(0) spreader c(L − 1) serial-to-parallel converter (0) d0 L−1 user group (K d0 −L) spreader c(L − 1) spreader c(0) 1st data symbol per user + (K d0 − 1) L−1 spreader c(L...

Ngày tải lên: 09/08/2014, 19:22

... [15] Kaiser S., “Trade-off between channel coding and spreading in multi-carrier CDMA systems, ” in Proc IEEE International Symposium on Spread Spectrum Techniques and Applications (ISSSTA’96), Mainz, ... International Symposium on Spread Spectrum Techniques and Applications (ISSSTA’98), Sun City, South Africa, pp 115–120, Sept 1998 [18] Kaiser S and Fazel K., “A spread- spectrum multi-carrier multiple-access ... Workshop on Multi-Carrier Spread- Spectrum (MC-SS’97), Oberpfaffenhofen, Germany, pp 49–56, April 1997 References 113 [19] Kaiser S and Fazel K., “A flexible spread spectrum multi-carrier multiple-access...

Ngày tải lên: 09/08/2014, 19:22

... Figure 4-17, CAZAC/M sequences are generated in the frequency domain and are embedded in I and R sequences The CAZAC/M sequences are differentially modulated The length of the M sequences is much ... sequences is much larger than the length of the CAZAC sequences The I and R sequences have the same length N1 , where in the I sequence (resp R sequence) the imaginary (resp real) components are ... frequency direction on OFDM symbols containing pilot symbols, followed by filtering in time direction on all sub-carriers is shown This ordering is chosen to enable filtering in frequency direction directly...

Ngày tải lên: 09/08/2014, 19:22

... band interference in PN spread- spectrum systems, ” IEEE, Transactions on Communications, vol 30, pp 913–924, May 1982 [44] Li Y., “Simplified channel estimation for OFDM systems with multiple transmit ... Effects of Phase Noise OFDM systems are more sensitive to phase noise than single-carrier systems due to the Nc times longer OFDM symbol duration and ICI [62][63] In OFDM systems, differential modulation ... information bits of each user k = 0, , K − 1, are spread by the corresponding spreading code, where Walsh–Hadamard codes are applied For the uplink, the spread data symbol of user k is mapped onto...

Ngày tải lên: 09/08/2014, 19:22

... to maintain orthogonality among the spread user signals by spreading in the time direction than in the frequency direction The concept of two-dimensional spreading is described in detail in Section ... For high coverage areas with high delay spread, large spreading factors can be applied and for low coverage areas with low delay spread, the smallest spreading factor can be used In HIPERLAN/2, ... support different multi-carrier or spread spectrum- based transmission schemes For instance, by choosing a spreading factor of one in both the time and frequency direction, one may obtain a pure...

Ngày tải lên: 09/08/2014, 19:22

... and Sawahashi M., “Variable spreading factor orthogonal frequency and code division multiplexing (VSF-OFCDM),” in Proc International Workshop on Multi-Carrier Spread- Spectrum & Related Topics (MC-SS ... how to exploit the frequency diversity are the technique of multi-carrier spread spectrum and coding in the frequency direction — Spatial diversity: Spatially separated antennas provide replicas ... required symmetrical or asymmetrical transmission capacity, and whether they Multi-Carrier and Spread Spectrum Systems K Fazel and S Kaiser  2003 John Wiley & Sons, Ltd ISBN: 0-470-84899-5 234 Additional...

Ngày tải lên: 09/08/2014, 19:22

... (STTC) 237–238 UMTS 253 Spatial diversity 233 Spreading codes 52–54 PAPR 54, 184–185 Spreading length 34, 49, 55, 201 Spread spectrum 30–45 Spread spectrum multi-carrier multiple access (SS-MC-MA) ... enlarging/spreading the spectrum Several spreading codes can be used for spectrum spreading Synchronous: users transmitting following a given time pattern Uplink (UL): direction from the TS to ... Small Office/Home Office Soft Output Viterbi Algorithm Serial-to-Parallel (converter) Spread Spectrum Spread Spectrum Multi-Carrier Multiple Access Solid State Power Amplifier Space–Time Coding...

Ngày tải lên: 09/08/2014, 19:22

... Direct- Sequence Systems with PSK Quadriphase Direct- Sequence Systems 6.3 Wideband Direct- Sequence Systems Multicarrier Direct- Sequence System Single-Carrier Direct- Sequence System Multicarrier DS/CDMA ... Orthogonal Sequences Sequences with Small Cross-Correlations Symbol Error Probability Complex-Valued Quaternary Sequences 6.2 Systems with Random Spreading Sequences Direct- Sequence Systems with ... 18 21 25 27 37 39 40 41 42 52 53 Direct- Sequence Systems 2.1 Definitions and Concepts 2.2 Spreading Sequences and Waveforms Random Binary Sequence Shift-Register Sequences Periodic Autocorrelations...

Ngày tải lên: 20/01/2014, 06:20

Ngày tải lên: 19/02/2014, 14:20

... EXACT BER ANALYSIS AND DESIGN OF PRERAKE COMBINING SCHEMES FOR DIRECT SEQUENCE ULTRA-WIDEBAND MULTIPLE ACCESS SYSTEMS CAO WEI (B Eng, M Eng) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR ... 136 List of Publications 137 vii Summary Recently, direct sequence ultra-wideband (DS UWB) communication systems have attracted much attention of both academia and industry because ... radio spectrum becomes very precious resource Though elaborate effort on well allocating spectrum resources has been continuously taken, it is necessary to find alternative approaches to exploit spectrum...

Ngày tải lên: 12/09/2015, 11:00

... động với FHSS Ví dụ Direct Sequence Spread Spectrum Transmitter Direct Sequence Spread Spectrum Transmitter Direct Sequence Spread Spectrum Using BPSK Example Approximate Spectrum of DSSS Signal ... mã PN gồm k chíp mã tương ứng với từ tần số Trải phổ dãy trực tiếp Direct Sequence Spread Spectrum    Direct Sequence Spread Spectrum (DSSS) Sử dụng mã trải phổ băng rộng để điều chế tín hiệu ... (Frequency Hopping Spread Spectrum FHSS): Hệ thống trải phổ cách nhảy tần số sóng mang tập lớn tần số, mẫu nhảy tần giả ngẫu nhiên Trải phổ dãy trực tiếp (Direct Sequence Spread Spectrum DSSS):...

Ngày tải lên: 13/09/2012, 11:16

... Reserved 18 Direct Sequence Spread Spectrum q Spread spectrum increases the bandwidth of the signal compared to narrow band by spreading the signal q There are two major types of spread spectrum ... Narrowband vs Spread Spectrum Narrowband (High Peak Power) Power Spread Spectrum (Low Peak Power) Frequency February 2005 Copyright 2005 All Rights Reserved Narrow Band vs Spread Spectrum q Narrow ... two spread spectrum techniques to be used in the licensed free Industrial, Scientific, Medical (ISM) band, 2.4 GHz, thus 802.11 and 802.11b Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence...

Ngày tải lên: 13/09/2012, 11:16

Ngày tải lên: 29/09/2013, 20:20

... requiring spread spectrum modulation: DSSS (Direct Sequence Spread Spectrum) and FHSS (Frequency Hopping Spread Spectrum) Only the RF transmission has significant presence in the market DSSS FHSS Spreading ... IQ-modulator Then they are spread with ‘ different’pilot sequences on the I and Q channels This pilot sequence or Short Code sequence has a length of 15 chips A ‘ PN-offset’in the pilot sequences is assigned ... hops/s or a channel dwell time of less than 400 ms DE NAYER (ir J Meel) IWT HOBU-fonds Spread Spectrum Spectrum The spectrum of the transmitted signals determines the network packing DSSS FHSS 11 Msps...

Ngày tải lên: 13/12/2013, 00:15