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CDMA (Download Full Seminar Report) - jayasandhya89 - 08-16-2017 [attachment=4612] This article is presented by: Malathy Elumalai Advance topics in Communication Spring 2010 COMPARISON OF CDMA AND TDMA SYSTEMS ABSTRACT In this report two candidates for high capacity cellular systems are simulated and analyzed, one CDMA and one TDMA system. Simulations of the CDMA example indicate a high sensitivity to variations in certain system parameters. The TDMA example is a GSM system using random frequency hopping and operating without frequency planning. The outage probabilities of both the systems that have been compared in the reference IEE paper are also simulated in this project. INTRODUCTION
In today s world cell phone have become the single greatest tool in day today life. It has become a necessity that business associates should be able to communicate on the go. That s why it has become so important to make choices in choosing which handheld device one should go for. A handheld device is selected according to its features and benefits, like does it provide access to internet and email or does it look slick and more.An important question when designing and standardizing cellular systems is the Selection of the multiple access schemes. Multiple Access methods address the problem of how many users can share the same spectrum resources in an efficient manner. We distinguish between them as follows Multiple access within one cell, i.e., a fixed assignment of resources in time or bandwidth to specific users Random access, i.e., a dynamic assignment of spectrum resources in time or bandwidth to users, according to their needs Frequency reuse, i.e., assignment of spectrum resources considering the location of users and the attenuation of radio signals that travel over sufficiently large distances Examples of multiple access schemes are FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access), and CDMA (Code Division Multiple Access). All three principles allow Multiple users to share the same physical channel. But the two competing technologies differ in the way user sharing the common resource. TDMA allows the users to share the same frequency channel by dividing the signal into different time slots. Each user takes turn in a round robin fashion for transmitting and receiving over the channel. CDMA uses a spread spectrum technology that is it spreads the information contained in a particular signal of interest over a much greater bandwidth than the original signal. In TDMA users can only transmit in their respective time slot. Unlike TDMA, in CDMA several users can transmit over the channel at the same time. CDMA (Download Full Seminar Report) - prakyath nonda - 08-16-2017 SUBIMITTED TO:-
ms. Neelam Arya Deptt. Of EC ITM GWALIOR SUBIMITTED BY:- Rajendra ku. Bansal [attachment=7800] Why CDMA? CDMA is extremely robust and provides excellent audio quality CDMA is the technology of choice for both 800 MHz Cellular and 1900 MHz PCS service providers CDMA satisfies CTIA Users Performance Requirements CDMA provides high capacity (many times the capacity of AMPS) CDMA provides privacy through its coding scheme What is Multiple Access? Multiple Access: Simultaneous private use of a transmission medium by multiple, independent users. Since the beginning of telephony and radio, system operators have tried to squeeze the maximum amount of traffic over each circuit Types of Media Twisted pair - copper Coaxial cable Fiber optic cable Air interface (radio signals) Advantages of Multiple Access Increased capacity: serve more users Reduced capital requirements since fewer media can carry the traffic Decreased per-user expense Easier to manage and administer Each pair of users enjoys a dedicated, private circuit through the transmission medium, unaware that the other users exist. Multiple Access Technologies Channel: An individually-assigned, dedicated pathway through a transmission medium for one user s information The physical transmission medium is a resource that can be subdivided into individual channels according to different criteria depending on the technology used: Here s how the three most popular technologies establish channels: FDMA (Frequency Division Multiplex Access) each user on a different frequency a channel is a frequency TDMA (Time Division Multiplex Access) each user on a different window period in time ( time slot ) a channel is a specific time slot on a specific frequency CDMA (Code Division Multiplex Access) each user uses the same frequency all the time, but mixed with different distinguishing code patterns a channel is a unique set of code patterns CDMA (Download Full Seminar Report) - dhan17 - 08-16-2017 (Code Division Multiple Access) A method for transmitting real-time signals over a shared portion of the spectrum. The foremost application of CDMA is the digital cellular phone technology that operates in the 800MHz band and 1.9GHz . Unlike GSM and TDMA, which divides the spectrum into different time slots CDMA uses a spread spectrum technique to assign a code to each conversation. After the speech codec converts voice to digital, CDMA spreads the voice stream over the full 1.25MHz bandwidth of the CDMA channel coding each stream separately so it can be decoded at the receiving end. The rate of the spreading signal is known as the chip rate, as each bit in the spreading signal is called a chip voice conversations use the full bandwidth at the same time. One bit from each conversation is multiplied into 128 coded bits by the spreading techniques, giving the receiving side an enormous amount of data it can average just to determine the value of one bit. http://pptpdf.net/subcategory.php?categ=unknown&categ_id=1&/computer%20science%20and%20electronics/Code%20Division%20Multiple%20Access.pdf&name=Code%20Division%20Multiple%20Access.pdf CDMA (Download Full Seminar Report) - harikrishnan.vadakkath - 08-16-2017 [attachment=5228] CDMA Tutorial CDMA (Download Full Seminar Report) (Code Division Multiple Access) A method for transmitting real-time signals over a shared portion of the spectrum. The foremost application of CDMA is the digital cellular phone technology that operates in the 800MHz band and 1.9GHz . Unlike GSM and TDMA, which divides the spectrum into different time slots CDMA uses a spread spectrum technique to assign a code to each conversation. After the speech codec converts voice to digital, CDMA spreads the voice stream over the full 1.25MHz bandwidth of the CDMA channel coding each stream separately so it can be decoded at the receiving end. The rate of the spreading signal is known as the chip rate, as each bit in the spreading signal is called a chip voice conversations use the full bandwidth at the same time. One bit from each conversation is multiplied into 128 coded bits by the spreading techniques, giving the receiving side an enormous amount of data it can average just to determine the value of one bit. for more http://seminarsprojects.net/Thread-cdma-download-full-seminars-report CDMA (Download Full Seminar Report) - dileep1304 - 08-16-2017 [attachment=4762] This article is presented by: SABYASACHI RANA SAPTARSHI CHATTERJEE AVIK MODAK ANURAN ROY CHOUDHARY C D M A
What is Multiple Access?
Simultaneous private use of a transmission medium by multiple, independent users. Advantages of Multiple Access Increased capacity: serve more users Reduced capital requirements since fewer media can carry the traffic Decreased per-user expense Easier to manage and administer MOST POPULER MULTIPLE ACCESS TECHNOLOGIES THAT ESTABLISHED CHANNELS FDMA (Frequency Division Multiplex Access) each user on a different frequency a channel is a frequency TDMA (Time Division Multiplex Access) each user on a different window period in time ( time slot ) a channel is a specific time slot on a specific frequency CDMA (Code Division Multiplex Access) each user uses the same frequency all the time , but mixed With different distinguishing code patterns a channel is a unique set of code patterns CDMA (Download Full Seminar Report) - basha - 08-16-2017 :[size=x-large]) hay now i am the member of your community so i want suggestions about my new project. |