Quiz 1 notes.txt

Ch 2. Invented by AT&T Bell in 1970 1G Systems: NMT – 1981 TACS – 1983 AMPS – 1983 These are important to know, but exact year is not necessary, same with full acronym. Just know generation and who invented it These systems are region locked Locations a...

Ch 2. Invented by AT&T Bell in 1970 1G Systems: NMT – 1981 TACS – 1983 AMPS – 1983 These are important to know, but exact year is not necessary, same with full acronym. Just know generation and who invented it These systems are region locked Locations are not important to know Different systems cannot communicate with each other Due to it just being deployed and high cost of devices, less than 1% of the world population used 1G Key Technologies Cellular Structure Analog FM FDMA (Frequency Division Multiple Access) (Need to know what FDMA stands for) If we have the frequency, we divide it into channels, and each user can use specific channels In the example we have 4 FM channels, so 4 users can use. Multiple users in the same cell can connect to the base station without colliding to each other when using different frequencies Cellular Structure Base stations have communication range, has cells, base stations (BS) and users Invented by AT&T Bell Disadvantages of 1G Large cell phone size Poor battery Poor voice quality No security Expensive service fee A type of question we might face What is the most important worth of 1G system? Cellular, because the same structure is being used until now and in the future Second Generation The keyword is Digital (binary, 0 and 1s) Deployed in 1990s 2G Systems: GSM – 1991 CDMA – 1995 US TDMA PDC (Japan) GSM cannot communicate with CDMA (region locked) 11% of population used it Key Technologies of 2G Digital Modulation BPSK – sends one bit per symbol (binary, 0 or 1) QPSK – sends two bits per symbol (00, 01, 10, 11) No need to memorize the acronym of these TDMA (Time division multiple access) Time is divided into different time slots, and during each time a user can use it. Diagram is on lecture slide CDMA (Code division multiple access) Coding data over bits, then sending it through medium (wireless) and then decode it. We will be asked to find the original data from coded data, for users like user 1 user 2 …. (we will learn coding and decoding) (in the future) 2G Services Data Service rate avg. 64 Kbps SMS (Short Message System) Limitations of 2G Slow data rate No video calls No web surfing Needs at least 1Mbps? (maybe for web surfing and video calls?) Comparison Comparison is on lecture slide Voice and Transmission are important changes Third Generation Similar to 2nd gen, it was digital Data bsed communication 3G Systems: Based on IMT – 2000 WCDMA CDMA2000 CDMA technology was developed by Qualcomm (know this) The standard organizations 3GPP and 3GPP2 is under IMT-2000 (know this) No new technology By upgrading the modulation technique, 2mbps was possible Modulation technique that was used is 16-QAM – 4 bit per symbol (2nd gen used QPSK (4-QAM) - 2 bit per symbol) This modulation technique raised the data to 2mbps instead of 64 kbps The reason 32 – QAM and 64 – QAM were not possible in the 3rd gen was because they didn't have the ability to check for errors in each bit, since there would be more bits the chances of error would be high, and quality would be low (not necessary to know FOR NOW) 1G-2G – revolution Analog to digital 2G-3G – technical evolution Technically no revolutionary changes CDMA was the only technique used anywhere in the world (know this) Data rate avg. 2mbps, up to 10mbps in the year 2008 Insufficient data rate for High quality multimedia services HD movies High quality video calls 10Mbps is not good enough for these, we need more. Fourth Generation Deployed in 2010s Over 7.5 billion subscribers (over 100%) Designed specifically for Data 3G was for voice and data Voice is a small portion of 4G, voice is treated as data Long Term Evolution (LTE) It is called LTE because an evolution happened, the voice being a data rather an analogue 3GPP is the only standard body developed 4G 4G used more bandwidth 5MHz -> 20MHz (what bandwidth means and etc. Will be explained, just know we had a certain bandwidth for 3G and previous, but now we have 20MHz in 4G More bandwidth = more data can be sent CDMA cannot be used with this wide bandwidth (20MHz) That's why they came up with OFDMA (orthogonal frequency divisional multiple access) a different technique Important development OFDMA was a revolution Started using multiple antennas for transmitting and receiving Started using MIMO (multiple input & multiple output) One protocol for voice and data (voice is included in data) Fourth Generation can also be called IP protocol 4G LTE Features High data rate of avg 100Mbps Can serve up to 100000 devices/km^2 at a time High speed up to 350km/h Ip based communication VoLTE (voice over LTE): all IP network Uses LTE standard system Fifth Generation (5G) Why we need 5G when 4G has enough data rate? IoT Virtual reality Online 3d games 3d video communication Target for the 5G Over 1gbps of data rate 1 million devices/km^2 Speed over 500km/h Around 1ms of transmission delay Spectral efficiency (bandwidth efficiency) Transmission bandwidth rate reaches 3 times (bps/Hz) 5G Technology More bandwidth by using millimeter wave, and upper band LTE frequency range 600MHZ to 6GHz Millimeter wave bands is 24-86GHz (don't have to memorize number, ut know what is LTE and millimeter wave) Many cells More cells = less users in each base stations Higher spectrum efficiency Massive MIMO NOMA Non-orthogonal multiple access Distinguishing user by using the power of the signal or the transmission New technology Massive connectivity IoT (Internet of Things) M2M (machine to machine) D2D (device to device)