If you want to buy cheap dsss compatible receiver, choose dsss compatible receiver from. Hi, i need a matlab source code for rake receiver in dsss system. Software dsss receiver block diagram my understanding. Direct sequence spread spectrum dsss each bit in original signal is represented by multiple bits in the transmitted signal spreading code spreads signal across a wider frequency band the amount of sperading is in direct proportion to number of pseudonoise pn bits used one technique combines digital information. Center for ocean research, saic, 10260 campus point drive, san diego, ca 92121. Mlse receiver for directsequence spreadspectrum systems on a multipath fading channel kai tang, member, ieee, laurence b. Rake receiver and multiple user transmission based on dsss are considered afterwards. Dsss receiver users manual u executive summary the directsequence spreadspectrum dsss receiver program is a multifaceted contribution to defence wireless communications capability it provides an alternative modulation scheme for specialpurpose link scenarios as well as an advanced. Capture effect in wireless lans with rake reception of. The rake receiver was patented in the us by robert price and paul e. How to design a rake receiver for dsss matlab answers. The rake receiver is a matched filter that uses a tap delay. In chapter 8 the simulation of the receiver with all. If the conditions on the multipathchannel change, the parameters of the rake receiver have to be adapted.
Qpsk dsss datasheet, cross reference, circuit and application notes in pdf. We then address multipath issues in wireless communications and show how code division multiple access cdma takes advantage of multipath in improving system performance with a rake receiver 6. Software rake receiver enhanced gps system daniel iancu, john glossner. What does this mean at the receiver cidsss receiver must. Analysis of spread spectrum system with rake same as previous diversity analysis. In telecommunications, directsequence spread spectrum dsss is a spreadspectrum modulation technique primarily used to reduce overall signal interference. The optimal receiver, which is best suited for our channel model, is the rake receiver. Noting that the desirable features of spread spectrum system rely heavily on the spreading signal design, we then discuss the design of spreading codes. Low complexity rake receiver and channel estimator. Frequencydomain prerake transmission transmitter and receiver structures for frequencydomain prerake transmission for a dssstdd system are illustrated in. Dsss communication system, as designed and analyzed in chapters 4, 5 and 6, were done prior to hardware implementation, in order to evaluate and verify correctness of the theoretical design. Mlse receiver for directsequence spreadspectrum systems on.
This thesis investigates the feasibility and performance of using directsequence spreadspectrum dsss modulation for utilitypacket transmission in seaweb underwater wireless acoustic communications networks. Receiver performs a time correlation operation to detect only desired codeword rake receiver multiple parallel receivers used to combat multipath interference and intersymbol interference telcom 2720 22 is95 multipath combining multipath. Cck encoding with pic based microcontrollers for the. Coherent rake receiver for cpmbased direct sequence spread. This report presents a comparative analysis of the performance of three uwb dsssrake modems used to communicate. Comparative performance of three dsssrake modems over. In this technology, a data signal at the sending station is combined with a high data rate bit sequence, which divides user data based on a spreading ratio. Covert underwater acoustic communications jun ling, hao he.
Spread spectrum multiple access the premise of spread spectrum multiple access is to modulate user signals with orthogonal or semiorthogonal codes. Our rake receiver is designed such that this delay range is taken care of. Implementing a rake receiver for wireless communications on. A rake receiver is a radio receiver which is designed for the purpose to counter the effects of multipath fading. Here, a bank of correlators is used to separate the m combining techniques for dscdma rake receiver ieee conference publication. Performance comparison of rake and hypothesis feedback.
Combine the chips and make final decision dsss combiner decision chip 0s receiver chip 1s receiver chip n1 s receiver rt. June 1990 microcellular directsequence spreadspectrum radio system using npath rake receiver urs grob, member, ieee, arnold l. Coherent rake receiver for cpmbased direct sequence. May 04, 20 roughly speaking,the rake receiver is an inverse of the multipath channel. Siegel, fellow, ieee abstract to accommodate highspeed data transmissions, it may be necessary to substantially reduce the. Mlse receiver for directsequence spreadspectrum systems. Implementing a rake receiver for wireless communications. Performance comparison of rake and hypothesis feedback direct.
It endeavors to provide the products that you want, offering the best bang for your buck. Direct sequence spread spectrum is often claimed to have particular properties that makes it less vulnerable to multipath reception. Rake receivers only became common after 16bit cpus capable of signal processing became widely available. I design a simple dsss transmitter but always do wrong about rake receiver. Can coherently combine all multipath components via a rake receiver 6 rake receiver lmultibranch receiver lbranches synchronized to different mp components lthese components can be coherently. In 3 the performance gain achieved with rake receivers in dscdma systems is shown. This report presents a comparative analysis of the performance of three uwb dsss rake modems used to communicate. Direct sequence spread spectrum lbit sequence modulated by chipsequence lspreads bandwidth by large factor g ldespread by multiplying by s c. Miriam leeser motorola, sps dept of electrical and computer eng. Recent listings manufacturer directory get instant insight. To get diversity gains over a rayleighfading multipath channel as in conventional direct sequence spreadspectrum binary phase shift keying dsss bpsk system, a new class of coherent rake receivers is proposed. Channel effects on directsequence spread spectrum rake.
If, in a mobile radio channel reflected waves arrive with small relative time delays, self interference occurs. The directsequence modulation makes the transmitted signal wider in bandwidth than the information bandwidth. Welti, student member, ieee, hans kaufma, member, ieee ernst zollinger, member, ieee, roland kung, member, ieee, and abstracta microcellular local area network lan for indoor com. Frequencydomain pre rake transmission transmitter and receiver structures for frequencydomain pre rake transmission for a dsss tdd system are illustrated in. Tang et al mlse receiver for directsequence spreadspectrum systems on a multipath fading channel 1175 fig. In chapter 7 the simulation of the dsss transmitter, employing complex spreading sequences, is done. Microcellular system we consider an indoor radio system using dsss with code division multiple access organized in a microcellular structure with one base station per cell. As you know, rake receiver is usually used with dsss modulation, so can we use it with ofdm. Roughly speaking,the rake receiver is an inverse of the multipath channel. A rake receiver is a radio receiver designed to counter the effects of multipath fading.
Green in july 1956, but it took until the 1970s to design practical implementations of the receiver. Pdf low complexity rake receiver and channel estimator. Letter, the achievable ber performance with the frequencydomain pre rake transmission is evaluated by computer simulation and compared with that of frequencydomain rake reception. The rake receiver consists of, of each finger in a rake receiver are allocated on the basis of the path searcher.
It despreads the received signal without demodulating it. Capture effect in wireless lans with rake reception of dsss. After this lecture you will be able to understand block diagram. Rake receiver for dsss systems file exchange matlab. The latter techniques have the advantage of causing far less time domain interference with other users. The use of a rake receiver in directsequence spreadspectrum systems provides a unique and valuable means of combating the adverse effects of shortterm multipath fading in radio propagation environments. Towards this goal, two promising variants of this technology, a rake based receiver architecture 2 and a hypothesisfeedback equalization based architecture 1are investigated. Sarkar department of electronics and telecommunication engineering jadavpur university kolkata 700032, india r. Combining techniques for dscdma rake receiver ieee. Qpsk dsss datasheet, cross reference, circuit and application notes in pdf format. Direct sequence spread spectrum dsss is a transmission technology used in local area wireless network transmissions.
On page 5 theres a summary, and the modulation is clearly called out as dsss direct sequence spread spectrum. Comparative performance of three dsssrake modems over mobile. Adv14ip is powered by a direct sequence spread spectrum dsss transceiver within the 225400 mhz frequency band, up to 1 mbps. Due to reflections from multiple obstacles in the environment, the radio channel can consist of multiple copies of the transmitted signal having different amplitude, phases or delays. Tapped delay line rake receivers are commonly used to achieve path diversity gain in dscdma systems. I believe fasst uses one pseudorandom sequence xord in with the data at high speed for dsss modulation, and a second low speed pseudorandom sequence xord in to the local oscillator which makes it hop across the entire 2. It does this by using several subreceivers called fingers, that is, several correlators each assigned to a different multipath component. Low complexity rake receiver and channel estimator implementation for dsss cdma systems athanasios doukas, georgios panitsas, christos masouros,grigorios kalivas department of electrical and computer engineering, university of patras patras, greece email. Low complexity rake receiver and channel estimator implementation for dsss cdma systems. Welti, student member, ieee, hans kaufma, member, ieee ernst zollinger, member, ieee, roland kung, member, ieee, and abstracta microcellular local area. Low complexity rake receiver and channel estimator implementation for dssscdma systems. May 06, 2018 hi guys in this lecture concept of direct sequence spread spectrum dsss are explained along with its advantages and application. Center for ocean research, saic, 10260 campus point drive, san diego, ca 92121 space and naval warfare systems center, san diego, san diego, ca 92152 abstract. Rake receiver for directsequence spread spectrum systems with document added 20 march 2009.
Implementing a rake receiver for wireless communications on an fpgabased computer system. After the despreading or removal of the directsequence modulation in the receiver, the information bandwidth is restored, while. Implementing a rake receiver for wireless communications on an fpgabased computer system ali m shankiti prof. Pdf performance of directsequence spreadspectrum rake. Bera sikkim manipal institute of technology sikkim. Low complexity rake receiver and channel estimator implementation for dssscdma systems athanasios doukas, georgios panitsas, christos masouros,grigorios kalivas department of electrical and computer engineering, university of patras patras, greece email. Capture effect in wireless lans with rake reception of dsssdpsk signals. Kandar sikkim manipal institute of technology sikkim manipal university majitar, sikkim 7376, india c. Role of rake receiver block diagram use, advantage, disadvantage conclusion. Dsss receiver, a new dimension of diversity reception is. Direct sequence spread spectrum dsss in hindi youtube. Hi guys in this lecture concept of direct sequence spread spectrum dsss are explained along with its advantages and application. Direct sequence spread spectrum dsss using continuous phase modulation cpm inherits the techniques benefits, constant envelope, antiinterference, and spectral efficiency. In the first technique, the channel is divided into equal subchannels.
Abstractdirect sequence spread spectrum dsss techniques for low probability of intercept lpi and multiuser communications applications for underwater acoustic communications are investigated. Combined trellis of dsss signal with bpsk data symbols on twotap isi channel,n 4. Channel effects on directsequence spread spectrum rake receiver during the kauaiex experiment paul hursky, vincent k. Cck encoding with pic based microcontrollers for the rf wireless communications boris ribov, grisha spasov abstract. Software rake receiver enhanced gps system daniel iancu, john glossner, hua ye, mayan moudgill, and vladimir kotlyar, sandbridge technologies, inc. A matched filter is essentially a subdesign of the rake receiver. Frequencydomain prerake transmission for dsss tdd mobile. Research article coherent rake receiver for cpmbased. Learning objectives multipath rake introduction how does it works. To get diversity gains over a rayleighfading multipath channel as in conventional direct sequence spreadspectrum binary phase shift keying dsssbpsk system, a new class of coherent rake receivers is proposed in. Capture effect in wireless lans with rake reception of dsss dpsk signals.
Pdf an2252 an2252 sc140 autocorrelation scrambling code rake complex dscdma cell search 2004 matlab rake. Two promising receivers, a rake based receiver and a hypothesisfeedback equalization based architecture are considered. You have to recover the spreading sequence timing when you despread basically your receiver looks for the correlation peak or peaks, if its a rake receiver, and locks its timing to that. Seaweb networks require robust channeltolerant utility packets having a low probability of detection. We first discuss the most popular spectrum spreading method, direct sequence spread spectrum dsss. Research article coherent rake receiver for cpmbased direct sequence spread spectrum kezhou, 1,2 shilianwang, 1 anderyangzhang 1 department of electronic science and engineering, national university of defense technology, changsha, china. A filter matched to a specific pseudo random pn sequence has an impulse response. Then these signalscan be separated out at receiver using the code properties. It does this by using several subreceivers called fingers, that is, several correlators each assigned to. It uses multipath combining diversity rake reception techniques to enhance radio communications against multipaths in harsh propagation conditions. Recombine the signal while effectively dealing with interchip interference.
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