It is usually expressed in decibels (dB). Sample Noise Power Values (kToB) Bandwidth Bandwidth Ratio (dB) Watts dBW dBm 1 Hz 0 4x10-21-204 -174 1 kHz 30 4x10-18-174 -144 1 MHz 60 4x10-15-144 -114 1 GHz 90 4x10-12-114 -84 NOISE POWER, kT oB Thermal noise is spread more or less uniformly ov er the entire frequency spectrum. On the other hand, for CDMA systems, the processing gain gives us an additional degree of freedom, so that we have the choice of several chip waveforms without incurring a loss in symbol rate. CDMA 2000 allowed for a second rate set at 14.4 kbps, producing higher voice quality. the CDMA systems. See also [16] and [17], [18] for other cross-layer . CDMA has 100% frequency reuse. Direct-sequence code-division multiple access (DS-CDMA) using multicarrier modulation has been extensively studied recently. If we assume that mobile transmit power is same for all user then mobile user near a cell jams a user that is distant from the cell. For the narrower bandwidth case, the processing gain factor, W/R, is reduced but the number of RF channels is increased by the same factor, resulting in no net change in capacity in the nominal case. allocation instead of by processing gain resulting from signal spreading. the well known formula of the probability For the narrower bandwidth case, the processing gain factor, W/R, is reduced but the number of RF channels is increased by the same factor, resulting in no net change in capacity in the nominal case. Explain Processing Gain in CDMA. This allows several users to share a band of frequencies (see bandwidth ). is given by the Cameron-Martin formula [14, Ch. Also "Process Gain" is defined as the difference in output and input SNR in any processor. On the one hand the longer the code, the higher the processing gain which enables us to allow more users in the system. This is conceptually similar to the contemporary multicarrier spread-spectrum . We consider only the uplink. Relation to CDMA and TDMA is provided. CDMA2000 includes − PROCESSING GAIN The Processing Gain and Capacity Relation Advantages of Spread Spectrum [15] conducted a similar study but with respect to determining the optimal CDMA processing gain for maximizing TCP throughput. The capacity of a CDMA system can be readily increased beyond that of (1) by applying additional techniques such as voice activity gating . Application of smart antennas in CDMA mobile communication system Application of smart antennas in CDMA mobile communication system Guo, Congliang 2001-10-18 00:00:00 ABSTRACT Full coverage in mobile service region will elate mobile telephone customers. The delivery of this course is very good. It then focuses on additional improvements brought by the third . 13b is 16. Proposed herein is a pre-processing technique applicable to maximum-SINR beamformers for "blind" space-time Rake receivers in "single-user"-type DS-CDMA detection. Tan F. Wong: Spread Spectrum & CDMA 6. In this paper, an analytical model is derived to evaluate the effect of both imperfect power control and imperfect sectorization on the performance of code division multiple access (CDMA) WLL systems. Explanation: UMTS (Universal Mobile Telephone System) is a visionary air interface standard that was introduced in 1996. For example, we could use chip waveforms of any excess band- width andmaintainthesamesymbolratebykeeping constant. P (gain) = 10log (W/R) W is Spread Rate R is Data Rate For CDMA P (gain) = 10log (1228800/9600) = 21dB Actual processing gain = P (gain) - SNR = 21 - 7 = 14dB CDMA uses variable rate coder The Voice Activity Factor of 0.4 is considered = -4dB. The processing gain for the matrices in FIG. code-division multiple-access (CDMA) system is one . Theoretical equations are given to allow performance estimates. It then focuses on additional improvements brought by the third . summarized in Table 1. the first type of processing gain, that is, the number of times each pulse is repeated (either uncoded or coded). The implementation strategy must be planned carefully because UMTS is a totally new system. The Spreading Factor is the ratio of the chips (UMTS = 3.84Mchips/s) to baseband information rate. If a code with a length of 16 bits is to be used then the processing gain is equivalent to 10 Log[16] dB or 12.04 dB. 12. 2.3 Code Division Multiple Access (CDMA) This technique allows the transmitters to send the information simultane-ously over a single communication channel. We see that combining equations \ref{2}, \ref{3}, and \ref{4} for the case of a rectangular window results in a processing gain of $10\log_{10}{N}$ which may ring bells for those familiar with spread spectrum and CDMA. 3.1 Uplink Coverage Analysis As a basis for the analysis of the effect of uplink capacity of coverage we can use the following formula for the received 9) Explain FDMA, TDMA, CDMA. First approach for reducing the interference is using the antenna sectorization. In order to gain insight into the performance of receivers in a DS-CDMA system with large processing gain and many users, much work has been devoted to the asymptotic analysis for synchronous DS-CDMA with random spreading [17, 7, 15]. Therefore, its spreading by 24/36 codes will have less than 24/36 processing gain. A schematic of a code sequence generator . It is usually expressed in decibels (dB). Processing gain = Tb/Tc It is also known as spreading factor. Chin' and K.J. All MSs are transmitting at power P. Considering only path loss (η = 4) determine the maximum value of M so that the uplink E b N 0 between any MS and the BS is at least 5. b. A system is disclosed for use in a wireless communication system to provide an estimated pilot signal. UMTS Radio System Planning. PG (dB) = SNR OUT (dB) - SNR IN (dB) Spreading Factor | Spreading Gain • Processing gain: the ratio between the transmission . Variable processing gain (VSG) and multi-codes (MC) are two interesting approaches for increasing transmission rate of data in CDMA [4]. An antenna array will attempt to increase gain based on the user's signal as received at the various elements in the array. Near Far effect is basic feature of CDMA. The spreading gain is variable to allow for different bit rates. for CDMA channels with deterministic signature waveforms spanning one symbol period. The spreading of the data signal in a cdma system is done by applying a code, independent of the data-signal. The process gain is the ratio by which unwanted signals or interference can be suppressed relative to the desired . Code Division Multiple Access (CDMA) relies on the use of spread spectrum techniques to achieve multiple . A pilot estimation component is in electronic communication with the front-end processing and despreading component for estimating . Application of the formula 4 to the shorter linear spreading codes results in Q×P groups respectively of Q×P matrices C n k of dimension Q×P, while the instance described before of the longer linear spreading codes resulted in Q×P groups respectively of Q×P matrices C n k of dimension . CDMA is the common platform on which 3G technologies are built. M J = G p L SYS . Near Far effect is basic feature of CDMA. The courseware is not just lectures, but also interviews. This is because pulse compression can still detect echo signals that have already disappeared in the noise before pulse compression. There is "process Gain, 10*log(Bc/Bb)" in DSSS system such as CDMA. c= Nis called the "processing gain" of the DSSS system nThe processing gain is also the ratio between the bandwidth of the spread signal to the bandwidth of the data signal nIn many cases, this is also the ratio of the height of the autocorrelation peak to the maximum sidelobe nThis ratio depends on the spreading code properties 8 Code-division multiple access ( CDMA) is a channel access method used by various radio communication technologies. Process Gain (Gp): It is the processing loss due to the receiver imperfections. If we assume that mobile transmit power is same for all user then mobile user near a cell jams a user that is distant from the cell. Code-selection has a large impact on the performance of the system. It first introduces simple but powerful properties of auto-correlation and cross-correlation of specific bit sequences, and then illustrates how a CDMA standard like cdmaOne 1 makes use of these properties. The CDMA U is dimensionless and bounded by 0≤ U≤ N. processing gain is G=W/Rs, where W Hz, the system bandwidth, is proportional to Rc. Downlink Beamforming for DS-CDMA Mobile Radio with Multimedia Services Ying-Chang Liang', Francois P.S. Y1 - 2005. European carriers, manufacturers, and government regulators collectively developed the early version of UMTS as an open air interface standard for third generation wireless telecommunication. Here, multicarrier implies N × 1.25 MHz channels overlaid on N existing IS-95 carriers or deployed on unoccupied spectrum. For DS-CDMA, it use ternary code (-1/0/1) because there is no binary code with both good autocorrelation and cross-correlation property. N2 - The objective of this thesis is to study adaptive modulation algorithms for Single Input Single Output (SISO) and Multiple Input Multiple Output (MIMO) channels. It first introduces simple but powerful properties of auto-correlation and cross-correlation of specific bit sequences, and then illustrates how a CDMA standard like cdmaOne 1 makes use of these properties. This problem may be present despite high processing gain. The spreading of the data signal in a cdma system is done by applying a code, independent of the data-signal. An interesting system was also developed which combines pseudo-noise spread spectrum with Fourier transform (Goldberg, 1981). I used the formula: BER = 0.5*erfc(SNR) for BPSK in AWGN channel to plot the picture which show relationship between BER and propagation distance through the relationship between SNR and distance based on free space path loss model. CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel. If we set the left hand side of (7) to that target SNR and solve for N, we find the basic capacity equation for CDMA: (8) Using the numbers for IS-95A CDMA with the 9.6 kbps rate set, we find (9) or about N=32. As a power quantity when expressed in dB as commonly done for "processing gain" would be $10\log_{10}(G_c/G_{nc})$. For working professionals, the lectures are a boon. In [15], the asymptotic output signal-to-interference-plus-noise ratio (SINR) of the MMSE receiver The capacity of a CDMA system can be readily increased beyond that of (1) by applying additional techniques such as voice activity gating . We'll see more details on n further, its values vary typically between 2 and 4 with the types of terrain. Dec 18, 2003 #2 flatulent Advanced Member level 5. 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