Introduction wireless communication network

Wireless communication description , introduction. basic concepts

1. 1 Introduction to Wireless Communications and Networks https://drive.google.com/drive/folders/1MOT1_zHe7TB_DuvFWoh-ywZkN6QaYwat?usp=sharing

2. Outline 2 Overview of a Communication System Digital vs. Analog Communications Examples of Wireless Communication Systems Why Wireless is Different ? Wireless System Architecture Multiple Access Techniques Evolution of Cellular Networks (1G ~ 3G) Wireless Local Area Networks (WLANs), Bluetooth and Personal Area Networks (PANs) Topics to be covered in the course

3. Wireless History Ancient Systems: Smoke Signals, Carrier Pigeons, … Radio invented in the 1880s by Marconi Many sophisticated military radio systems were developed during and after WW2 Cellular has enjoyed exponential growth since 1988 Ignited the wireless revolution Voice, data, and multimedia becoming ubiquitous Use in third world countries growing rapidly Wifi also enjoying tremendous success and growth Wide area networks (e.g. Wimax) Short-range systems: Bluetooth, UWB, …

4. Components of a Communication System (1) Figure 1: Communication Systems 4

5. Components of a Communication System (2) 5 The source originates a message, which could be a human voice, a television picture or data. The source is converted by an input transducer into an electrical waveform referred to as the baseband signal or message signal. The transmitter modifies the baseband signal for efficient transmission. The transmitter generally consists of one or more of the following subsystems: a pre-emphasizer, a sampler, a quantizer, a coder and a modulator. The channel is a medium through which the transmitter output is sent, which could be a wire, a coaxial cable, an optical fiber, or a radio link, etc. Based on the channel type, modern communication systems are divided into two categories: wireline communication systems and wireless communication systems.

6. Components of a Communication System (3) 6 The receiver reprocessed the signal received from the channel by undoing the signal modifications made at the transmitter and the channel. The task of the receiver is to extract the message from the distorted and noisy signal at the channel output. The receiver may consist of a demodulator, a decoder, a filter, and a de-emphasizer. The receiver output is fed to the output transducer , which converts the electrical signal to its original form. Transmitters and receivers are carefully designed to overcome the distortion and noise. The Goal of Physical layer Communication System is to transmit information accurately and efficiently (power and spectrum).

7. Wireless System Definitions (1) Mobile Station A station in the cellular radio service intended for use while in motion at unspecified locations. They can be either hand- held personal units (portables) or installed on vehicles (mobiles) Base station A fixed station in a mobile radio system used for radio communication with the mobile stations. Base stations are located at the center or edge of a coverage region. They consists of radio channels and transmitter and receiver antennas mounted on top of a tower.

8. Wireless System Definitions (2) Mobile Switching Center Switching center which coordinates the routing of calls in a large service area. In a cellular radio system, the MSC connections the cellular base stations and the mobiles to the PSTN (telephone network). It is also called Mobile Telephone Switching Office (MTSO) Subscriber A user who pays subscription charges for using a mobile communication system Transceiver A device capable of simultaneously transmitting and receiving radio signals

9. Wireless System Definitions (3) Control Channel Radio channel used for transmission of call setup, call request, call initiation and other beacon and control purposes. Forward Channel Radio channel used for transmission of information from the base station to the mobile Reverse Channel Radio channel used for transmission of information from mobile to base station

10. Wireless System Definitions (4) Simplex Systems Communication systems which provide only one-way communication Half Duplex Systems Communication Systems which allow two-way communication by using the same radio channel for both transmission and reception. At any given time, the user can either transmit or receive information. Full Duplex Systems Communication systems which allow simultaneous two-way communication. Transmission and reception is typically on two different channels (FDD).

11. Wireless System Definitions (5) Handoff The process of transferring a mobile station from one channel or base station to an other. Roamer A mobile station which operates in a service area (market) other than that from which service has been subscribed. Page A brief message which is broadcast over the entire service area, usually in simulcast fashion by many base stations at the same time.

12. Digital vs. Analog Communications (1) 12 Analog and Digital Signals Messages are digital or analog. Digital messages are constructed with a finite number of symbols. For example, a text file is a digital message constructed from 50 symbols, consists of 26 letters, 10 numbers, a space and several punctuation marks. Similarly, a Morse-coded telegraph is a binary message, implying only two symbols – mark and space. Analog messages are characterized by data whose values vary over a continuous range. For example, a speech waveform has amplitudes that vary over a continuous range. A picture is also an analog message.

13. Noise immunity of digital signals 13

14. Digital vs. Analog Communications (2) 14 Noise immunity of digital signals – digital data can be recovered without any error as long as the distortion and noise are within limits. On the other hand, for an analog message, even a slight distortion or interference in the waveform will cause an error in the received signal. Regenerative repeaters ––Based on this “noise immunity”, when transporting a bit stream over a long distance, regenerative repeaters or repeater stations are placed along the path of a digital system at distances short enough to ensure that noise and distortion remain within a limit. The viability of regenerative repeaters is the main reason for the superiority of digital systems over analog ones. Every possible communication can be carried on with a minimum of two symbols , i.e., by using a proper binary sequence. In the last 20 years, digital communication gradually replace its analog competitors, and the revolution is now nearly complete.

15. Interface of Analog and Digital Systems -- A/D and D/A Conversion 15 Sampling Theorem A meeting ground exists for analog and digital signals: conversion of analog signals to digital signals. The backbone that supports the interface is Shannon's Sampling Theorem, which states that if the highest frequency in the signal spectrum is B (in hertz), then the signal can be recovered from its samples, taken at a rate not less than 2B samples per second. Quantization each sample is approximated, or round off to the nearest quantized level, the information is thus digitalized. The quantized signal is an approximation of the original one. We can improve the accuracy of the quantized signal to any desired degree by increasing the number of levels. Coding Source coding Convert the quantized signal into binary sequences. Channel coding Introduce redundancy in a controlled manner to overcome the effects of noise and interferences. Mapping Map binary sequence into symbols. Transmission Symbols are applied to a transmitter filter, which produces a continuous signal for transmission over a continuous channel.

16. Examples of Wireless Communication Systems 10 Codeless telephones --- use radio to connect a portable handset to a dedicated base station over a distance of a few tens of meters. Paging systems --- Communication systems that broadcast a page from every base station in the network and send brief messages to a subscriber. Cellular telephone systems --- provide a wireless connection to the PSTN (Public Switched Telephone Network) for any user location within the radio range of a system. Garage car opener Remote controllers for home entertainment equipment Hand-held walkie-talkies Wireless keyboard and mouse Wireless Lan router and adapter ■ …..

17. Wireless Vs. Wireline Communications ---- Challenges in Wireless Communication Systems 17 Wireless channel Have time varying and multipath propagation properties. Communicate over a medium significantly less reliable than wired physical layer. Are unprotected from outside signals and interceptions. Multiuser interference (MUI) is a significant problem in wireless communications. Has neither absolute nor readily observable boundaries outside of which stations are known to be unable to receive network frames. User Mobility Destination address does not equal to a fixed destination location. Power management --- performance, interference lever and power consumption. Hand-off --- A mobile switches its serving base station while moving from cell to cell. Location management --- tracks the user’s movement, support users roaming delivers calls to the user at its current location.

18. Trends on Wireless Communications Rapid growth In the last few decades, new and cheaper wireless services are emerging continuously, due to advances in: Digital signal processing Digital and RF circuit fabrication Large scale circuit integration Digital switching techniques -> large scale deployment of radio communication networks Convergence of wireless and Internet ---- Broadband communications 3G cellular and PCS networks WLAN networks Ad-hoc Networks ( military ) 18

19. Cellular System Architecture Core Network Core Network Backbone Emergency Service Internet PSTN Mobile RNC Node B Mobile Radio Access 19 Node B

20. Cellular System Architecture 20 Radio Access : RF related signal processing and radio resource management. Mobile => base station => BSC or RNC => MSC. Core Network : Main part is MSC (mobile switching center), performs user authentication, admission control, traffic control, roaming, billing, network support and maintenance etc. Backbone networks : Providing voice services (PSTN, Public Switched Telephone Network), data services (through Internet), and emergency services. Wireless networks need to be connected to backbone networks to extend its service capabilities and geographic coverage.

21. Multiple Access Techniques 21

22. Multiple Access Techniques 22 FDMA (Frequency Division Multiple Access) each user is allocated a unique frequency band or channel, no other user can share the same frequency band. TDMA (Time Division Multiple Access) divides the radio spectrum into time slots, and in each slot, only one user is allowed to either transmit or receive. CDMA (Code Division Multiple Access) each user is assigned a special code sequence (signature) to modulate its message signal, all users are allowed to transmit over the same channel simultaneously and asynchronously. SDMA (Space Division Multiple Access) controls the radiated energy for each user in space. SDMA serves different users by using spot beam antennas.

23. How a cellular telephone call is made? 23 Receiving a call Turn on a cellular phone The cellular phone scan the control channels to determine the one with the strongest signal, it then monitors the signal drops below a usable level. At his point, it starts to search of strongest base station again. If a phone call is placed to a mobile user, the MSC dispatches the request to all the base stations in the system, the MIN (mobile identification number, i.e. the mobile’s phone number) is broadcast as a paging message through the forward control channel. The mobile receives the signal through the base station it monitors and responds by identifying itself through the reverse control channel. The base station informs the MSC of the handshake. The MSC instructs the base station to move the call to an unused voice channel within the cell. The base station signals the mobile to change frequencies to the unused unused forward and reverse voice channel pair. The base station instructs the mobile phone to ring, thereby to instruct the user to answer the phone.

24. How a cellular phone call is made (continued) 24 Initiating a call The mobile sends a call initiation request through the reverse control channel, with this the unit transmits its MIN, ESN (electronic serial number) and the phone number of the called party. Base station receives the request and sends it to the MSC. The MSC validates the request, making connection to the called party through PSTN. The MSC instructs the base station and mobile user to move to an unused forward and reverse voice channel pair. Roaming All cellular systems provide a service called roaming . This allows subscribers to operate in service areas other than the one from which the service is subscribed . The MSC issues a global command every several minutes, asking all unregistered mobiles to report their subscription information. Mobiles report back upon receiving the request. If the mobile has roaming authorization for billing purpose, the MSC registers the subscriber as a roamer .

25. 25 The third generation cellular networks were developed with the aim of offering high speed data and multimedia connectivity to subscribers. The International Telecommunication Union (ITU) provides the standard known as, IMT-2000 (International Mobile Telecommmunications-2000). IMT-2000 is intended to form the basis for 3G systems. The aim of IMT-2000 is to harmonize worldwide 3G systems to provide Global Roaming . 3G System

26. 26 A few technologies are able to fulfill the International Mobile Telecommunications (IMT) standards, such as CDMA, UMTS and some variation of GSM such as EDGE.

27. 27 For IMT-2000 intended Data Rates Low 144 kbits/s satellite and rural outdoor, Medium 384 kbits/s urban outdoor, High 2048 kbits/s indoor and low range outdoor. The speed of the MS above 10 Kmph will loose data rate.

28. 28 Common Spectrum worldwide (1.8-2.2GHz band) Multiple radio environments (cellular, cordless, satellite, LANs) Wide range of telecommunication services (voice, data, multimedia, Internet) Global seamless roaming Enhance security and performance Integration of satellite and terrestrial system. IMT-2000 Vision

29. 29 After trying to establish a single 3G standard, ITU finally approved a family of 3G standards, which are part of the 3G framework known as IMT-2000: W-CDMA CDMA2000 TD-SCDMA (Time Division- High Speed Circuit Switched Data )

30. 30 IS-95 IS-136 & PDC GSM- EDGE GPRS HSCSD IS-95B Cdma2000-1xRTT Cdma2000-1xEV,DV,DO Cdma2000-3xRTT W-CDMA EDGE TD-SCDMA 2G 3G 2.5G 3GPP 3GPP2 Evolution to 3G AMPS IS-41 ETACS Advanced Mobile Phone System European Total Access Communication System United States Digital Cellular Global Systems for Mobile Cellular Digital Packet Data AMPS ETACS U S DC GSM CD P D GPRS ED G E General Packet Radio Service Enhanced Data Rates for GSM Evolution U M TS 3GPP Universal Mobile Telecommunications System 3 rd Generation Partnership Project

31. 1G Wireless Systems 20 Appeared in late 1970s and deployed in early 1980s. All based on analog techniques, all used FDMA and FM modulation. System capacity is low . Data rate: 8~10 kbps Representative Standards: AMPS: Advanced Mobile Phone System, developed by AT&T Bell Labs in late 1970s. First deployed in 1983. The first AMPS system used large cells and omni-directional base station antennas, therefore, the number of users that can be supported was quite limited. AMPS is used all over the world and is esp. popular in US, South America, China and Australia. ETACS: European Total Access Communication Systems. Almost identical to AMPS except that the channel bandwidth is scaled to 25kHz instead of 30 kHz as in AMPS.

32. 2G Wireless Systems: Characteristics 32 Deployed in mid 1990s, 2G wireless systems all use digital voice coding and digital modulation. Can provide advanced call capabilities and at least a 3- times increase in overall system capacity. Was designed before the widespread of the Internet, mainly supported voice-centric services and limited date-service, like short messages, FAX,etc. Date rate: on the order of 10 kbps

33. 33 GSM evolution to 3G GSM 9.6kbps (one timeslot) GSM Data Also called CSD GSM General Packet Radio Services Data rates up to ~ 115 kbps Max: 8 timeslots used as any one time Packet switched; resources not tied up all the time GSM / GPRS core network re-used by WCDMA (3G) GPRS HSCSD High Speed Circuit Switched Data Dedicate up to 4 timeslots for data connection ~ 50 kbps Good for real-time applications (better than GPRS) Inefficient in a sense that ties up resources, even when nothing is sent Not as popular as GPRS (many skipping HSCSD) EDGE Enhanced Data Rates for Global Evolution Uses 8PSK modulation 3x improvement in data rate on short distances Can fall back to GMSK for greater distances Combine with GPRS (EGPRS) ~ 384 kbps Can also be combined with HSCSD WCDMA

34. 2G Wireless Systems: Representative Standards 34 GSM ( Global Systems for Mobile communications) A TDMA system, serves as the pan-European cellular service, provides a wide range of network service, including phone service, FAX, short message service. Support 24.7kbps data rate. USDC IS-136 ( United States Digital Cellular) A TDMA system which is compatible with AMPS, it supports more users (6 times) with improved performance. It shares the same frequencies, frequency reuse plan and base stations as AMPS. Provides access to VPN, supports short messages. Support 48.6kbps data rate. IS-95 (United States D igital Cellular Standard ) A CDMA standard also designed to be compatible with AMPS through using of CDMA/AMPS dual mode phones and base stations. Capacity is 8~10 times that of AMPS. Support 14.4kbps data rate.

35. 2.5G Wireless System 35 Compared to 2G systems, 2.5G systems enables high speed data communications, provides continuous connection to internet. CDPD ( Cellular Digital Packet Data), a data service for 1st and 2nd generation US cellular systems without additional bandwidth requirement, packet channels are dynamically assigned to idle voice channels. Support 48.6kbps data rate as in IS-136. GPRS ( General Packet Radio Service), based on GSM by allowing multiple slots of a GSM radio channel be dedicated to an individual user, promises data rate from 56 kbps to 114kbps --- continuous connection to the Internet for mobile phone and computer users, easy access to VPN (Virtual Private Network). EDGE ( Enhanced Data Rates for GSM Evolution), providing 384kbps rate by using improved modulation (8-PSK instead of GMSK in GSM) and relaxed error control. Also referred to as EGPRS. CDMA one (IS-95B) : Providing high speed data access on a common CDMA radio channel by dedicating multiple orthogonal user channels for specific users or specific purposes. Support 115.2kbps .

36. 36 UMTS UMTS is the European vision of 3G. UMTS is an upgrade from GSM via GPRS or EDGE. The standardization work for UMTS is carried out by Third Generation Partnership Project (3GPP). Data rates of UMTS are: 144 kbps for rural 384 kbps for urban outdoor 2048 kbps for indoor and low range outdoor Virtual Home Environment (VHE)

37. 37 A UMTS network consists of three interacting domains: Core Network (CN), UMTS Terrestrial Radio Access Network (UTRAN) and User Equipment (UE) or ME. The 3G system terminal is called ‘‘UE’’ and it contains two separate parts, Mobile Equipment (ME) and the UMTS Service Identity Module (USIM). USIM contains member specific data and enables the authenticated entry of the subscriber into the network. UMTS System Architecture

38. 38 UMTS network architecture Circuit switch domain Packet switch domain GERAN: GSM EDGE Radio Access Network The GERAN air interface is Um, whereas the UTRAN air interface is Uu

39. 39 This UMTS UE is capable of working in three modes: CS (circuit switched) mode, PS (packet switched) mode and CS/PS mode.

40. 40 Base Station is referred as Node-B and control equipment for Node-B's is called Radio Network Controller (RNC) as if the BSC of GSM. The functions of Node-B are: Air interface Transmission / Reception Modulation / Demodulation CDMA Physical Channel coding Micro Diversity Error Handing Closed loop power control The functions of RNC are: Radio Resource Control Admission Control Channel Allocation Power Control Settings Handover Control Macro Diversity Ciphering Segmentation / Reassembly Broadcast Signaling Open Loop Power Control

41. 41 Core Network (CN) : The Core Network is divided in circuit switched and packet switched domains. Some of the circuit switched elements are Mobile services Switching Centre (MSC), Visitor location register (VLR) and Gateway MSC. Packet switched elements are Serving GPRS Support Node (SGSN) and Gateway GPRS Support Node (GGSN) . Some network elements, like EIR, HLR, VLR and AUC are shared by both domains. To provide switching, routing and transit for user traffic. The basic CN architecture for UMTS is based on the GSM network with GPRS.

42. 42 Serving GPRS Support Node (SGSN) interfaces the access network of MS and the Gateway GPRS Support Node (GGSN) connects UMTS core network with external packet network like Internet, X.25 or similar. The Asynchronous Transfer Mode (ATM) is defined for UMTS core transmission. The ATM Adaptation Layer type 2 (AAL2) handles the circuit switched connection and the packet connection protocol AAL5 is designed for data delivery.

43. 43 UMTS Network Architecture

44. 44

45. 45 Two international bodies are established. Third Generation Partnership Project (3GPP) The Japanese standardization body ARIB (Association of Radio Industries and Business), Telecommunications Industry Association (TIA) of Korea, ESTI (European Telecommunication Standards Institute) of Europe proposed for WCDMA is based on DS-CDMA (direct sequence code division multiple access) technology. Third Generation Partnership Project 2 (3GPP2) , A partnership consisting of five telecommunications standards bodies: CWTS in China, ARIB and TTC in Japan, TTA in Korea and TIA in North America proposed for CDMA-2000 . Bodies Give Proposal for 3G

46. 46 3GPP North America T1 Europe ESTI China CWTS Japan ARIB/ TTC Korea TTA T1 →ANSI Committee CWTS → China Wireless Telecommunications Standard

47. 47 3GPP2 North America TIA China CWTS Japan ARIB/ TTC Korea TTA

48. 48 TIA of USA and TTA of Korea proposed 3G CDMA-2000. Code division multiple access 2000 is the natural evolution of IS-95 (cdmaOne). It includes additional functionality that increases its spectral efficiency and data rate capability. CDMA (code division multiple access) is a mobile digital radio technology where channels are defined with codes (PN sequences). CDMA permits many simultaneous transmitters on the same frequency channel. 3G CDMA-2000

49. 49 IS-95B IS-95B Uses multiple code channels Data rates up to 64kbps Many operators gone direct to 1xRTT CDMA IS-95A IS-95A 14.4 kbps Core network re-used in CDMA2000 1xRTT CDMA2000 1xRTT( Radio Transmission Technologies ): single carrier RTT First phase in CDMA2000 evolution Easy co-existence with IS-95A air interface Release 0 - max 144 kbps Release A – max 384 kbps Same core network as IS-95 1xEV-DO CDMA2000 1xEV-DO: (Evolution-Data Only) 1XEV-DO, also called 1XEV Phase One, is an enhancement that puts voice and data on separate channels in order to provide data delivery at 2.4 Mbps. 1xEV-DV CDMA2000 3xRTT EV-DV, or 1XEV Phase Two promises data speeds ranging from 3 Mbps to 5 Mbps. CDMA20003X evolution: speeds to 5Mbps (more than 3xRTT i.e. 3 times the standard 1.25 MHz ) CDMA2000 evolution to 3G

50. 50 Evolution to 3G – The Carrier’s Choice 1995 1999 2000 2001 2002 Nearly Doubles Voice, 307k, RF backward compatible Data only 2.4 Mbps RF backward compatible Voice, 14.4k Voice, 64k CDMA CDMA2000 1x IS-95A CDMA2000 1xEV-DO IS-95B 2003 2004 Evolution of CDMA Networks

51. 51 Time Division-Synchronous Code Division Multiple Access, or TD-SCDMA, is a 3G mobile telecommunications standard, being pursued in the People's Republic of China by the Chinese Academy of Telecommunications Technology (CATT). This proposal was adopted by ITU as one of the 3G options in late 1999. TD-SCDMA is based on spread spectrum technology. 3G TD-SCDMA

52. 52

53. 53 Three system parameters coverage area of a cell, quality of voice and capacity of physical channel are interlinked. Enhancement of any parameter will degrade another two parameters. For example if coverage area of a cell is increased then delay difference of multipath propagation will also increase hence BER will be high. To keep the BER within tolerable range chip rate i.e. capacity of the channel has to be reduced or size of the cell must be lowered to reduce the delay difference of mulipath propagation. Capacity Coverage Quality Three system parameters

54. CDMA 54

55. 55 CDMA physical channels are defined by RF frequency and code sequence. The logical channels in CDMA are the control and traffic channels Physical and Logical channel The Forward CDMA channel is the cell-to-mobile direction of communication or the downlink path. The Reverse CDMA channel is the mobile-to-cell direction of communication or the uplink path. Forward and Reverse Channel

56. 57

57. 58 Each Walsh code identifies one of the 64 forward channels. After the channel symbols are spread using orthogonal codes, they are further scrambled in the in-phase and quadrature phase lines by what are called the short PN-spreading codes . The PN-spreading codes (period of 32,768 chips) are orthogonal but possesses excellent autocorrelation and cross correlation properties to minimize interference among different channels. Orthogonal codes are used to isolate the transmission between different channels within a cell and the PN spreading codes are used to separate the transmission between different cells. In effect the PN sequences are used to differentiate between several BSs in the areas that are all employing the same frequency. CDMA Forward Channel

58. 59 It is a pseudo-noise code sequence Each user has a unique PN code orthogonal to all other users. Orthogonal Walsh codes are generated from Hadamard matrices. PN Sequence The forward link ( base station to mobile station ) uses Walsh codes , while the reverse link ( mobile station to base station ) uses pseudo-random noice (PN) codes for channelization.

59. 60 a a a a 1 1 1 1 OR =

60. 61 0 0 0 1 0 0 0 1 0 0 0 1 1 1 1 0 1 1 1 0 1 1 1 0 1 1 1 0 0 0 0 1 4 ×4 matrix (4-bits Walsh codes)

61. 62 Pilot Channel The pilot channel is intended to provide a reference signal for all MSs within a cell that provides the phase reference for coherent demodulation. Its data content is a sequence of zero contains no information except the RF carrier. It is about 4-6dB stronger than all other channels. It is also spread using PN-spreading code to identify the BS. The way to identify the BS is to offset (shift of chip sequence) the PN sequence by some number of chips. To QPSK modulation BPF BPF All 0s I pilot PN at 1.2288 Mcps Q pilot PN at 1.2288 Mcps Walsh W 1.2288 Mcps BBF- Baseband Filter

62. 63 Each pilot channel transmits the same spreading sequence at different time offset (in IS-95 offset of 64 chips is used), which can be used to distinguish signals of different pilots. There are 512 offset values available i.e. 512 possible spreading sequences that can be reused elsewhere in the same system. The pilot channel consists of an un-coded direct sequence spread spectrum signal with its own identifying spreading code and is shared among all users in a sector or cell. To QPSK modulation BPF BPF All 0s I pilot PN at 1.2288 Mcps Q pilot PN at 1.2288 Mcps Walsh W 1.2288 Mcps BBF- Baseband Filter

63. 64 Uniquely identifying sector/cell Providing phase/time/signal strength reference Rescanning or periodically checking for better sector/cell 4-6dB stronger than other channels No power control in pilot channel A summery of pilot channel

64. 65 Sync Channel The synchronization channel is used to acquire initial time synchronization. It provides a mobile with the system and network identification parameters required to synchronize with the network and obtain a paging channel. Sync channel message 1.2 kbps Convolutional encoder Symbol repetition Block interleaver Rate ½ Code Symbol 2.4 ksps 4.8 ksps Modulated Symbol To QPSK modulation BBF BBF 4.8 ksps I pilot PN at 1.2288 Mcps Q pilot PN at 1.2288 Mcps Walsh W 32 1.2288 Mcps

65. 66 System identification number (SID) Network identification number (NID) Verion of radio interface being supported Precise time-of-day information PN offset of the associated pilot channel Uses W32 for spreading Operates at 1200bps Provides paging channel data rate A summery of synchronization channel

66. 67 Paging Channel Paging channel message 4.8 or 9.6 kbps Convolutional encoder Symbol repetition Block interleaver Rate ½ Code Symbol 9.6 or 19.2 ksps 19.2 ksps Modulated Symbol To QPSK modulation BBF BBF I pilot PN at 1.2288 Mcps Q pilot PN at 1.2288 Mcps Walsh W 1-7 1.2288 Mcps 19.2 ksps Long code mask for paging channel Long code generator Long code decimator 1.2288 Mcps 19.2 ksps 64:1

67. 68 Used to page the MS (like GSM) in case of an incoming call, or to carry the control messages for call set up . Provides notification of incoming call. Paging channel can be used to broadcast messages. Uses W1-W7 There is no power control Additionally scrambled by PN long code, which is generated by LFSR (Linear Feedback Shift Register) of length 42 The rate 4.8 Kbps or 9Kbps Provides list of CDMA carriers.

68. 69 This channel is used for voice communication and signaling to a specific mobile during a call. Traffic (channels 8 to 31 and 33 to 63) – the forward channel supports 55 traffic channels. Supported data rates are up to 9600bps in the first proposal and 14400bps in the revision. Forward Traffic Channel Gain Control Baseband Filter Baseband Filter I PN Q PN 1.2288 Mcps Walsh Function Block Interleaving symbol Repetition 19.2 Ksps Decimator Long PN Code Generator Scrambling Long Code Mask 1.2288 Mcps 19.2 Ksps Voice traffic Power Control Bits 800 bps Decimator 800 Hz M U X Puncture 2 of every 6 input 28.8 Ksps bits chips CHANNEL ELEMENT R = 1/2, Convolutional Encoding 64:1 24:1 19.2 Ksps

69. 70 Scrambler Used for Data Encryption. Make call more secure. Randomizes data. Prevents the transition of a long series of 1’s or 0’s Decimator Under samples pulses

70. 71 Forward Traffic Channel Processing Steps Speech is encoded at a rate of 8550 bps Additional bits added for error detection Data transmitted in 2-ms blocks with forward error correction. Data interleaved in blocks to reduce effects of errors Data bits are scrambled, serving as a privacy mask Power control information inserted into traffic channel Digital bit stream modulated onto the carrier using QPSK modulation scheme

71. 72 The CDMA reverse channel (MS to BS) is fundamentally different from forward channel. It employs OQPSK (Offset QPSK) rather than OPSK since OQPSK is more power efficient for MS as a transmitter. Compared with the forward channel, there is no spreading of data symbol using orthogonal codes but uses waveform encoding (orthogonal modulation scheme) that consume BW but reduces BER (Bit Error Rate). CDMA Reverse Channels

72. 73

73. 74 The reversed access channel is one-third rate convolutionally encoded, interleaved spread-spectrum channel. It is used by a mobile to initiate a call with base station and to response to paging channel message. The reverse channel is spread by one of 2 42 -1 PN code. The encoded spread-spectrum data are then MOD2 added with the I and Q PN sequence and finally modulated. Access Channel

74. 75 Access message 4.8 kbps Convolutional encoder Symbol repetition Block interleaver Rate ½ Code Symbol 14.4 ksps 28.8 ksps Modulated Symbol To QPSK modulation BBF BBF I pilot PN at 1.2288 Mcps Q pilot PN at 1.2288 Mcps 1.2288 Mcps 64-ary orthogonal modulator 28.8 ksps Long code generator Long code mask for access channel Reverse Access Channel

75. 76 Bit rate 9600 and 4800bps System access Traffic channel request Call originations Page response System registration Summary of Reverse Access Channel

76. 3G Wireless Systems: Features 77 Features: High transmission rate and the support of multimedia services . Multiple-megabit internet services, and simultaneous voice and data access with multiple parties at the same time using a single mobile handset. Date rate: around 2Mbps. Bandwidth: in the order of MHz Seamless global roaming: wireless access from anywhere on the earth. Obviously, it will include the satellite networks. 3GPP and 3GPP2 Worldwide standardization organizations established to gather global expertise, participated by almost all the big companies . 3GPP: based on backward compatibility to GSM, IS-136, GPRS, EDGE etc. 3GPP2: based on backward compatibility to IS-95, and CDMAone.

77. 3G Wireless Systems: Challenges 78 Impact of high transmission rate --- frequency selective fading High transmission rate implies that the signal bandwidth is much wider than the coherence bandwidth of the channel, different frequency components in the signal will experience different fading characteristic. Solution : Modulate each signal components onto a different subcarrier and send them over the channel in parallel, so that each component will experience flat fading. => multicarrier systems. System capacity and user mobility Enlarged capacity and higher transmission rate requires more efficient deployment of the available bandwidth, which implies that the system needs to be reused more often. Higher degree of frequency reuse implies more complex mobile management. How to increase spectrum efficiency is the ultimate goal of communication research .

78. 79 Where I t is the total interference and thermal noise psd and E b is energy per bit. Signal strength in dB, S=P m +G m +G b +M fade +L p +L cable +L body +L pent R = transmission rate of MS in bps B w = bandwidth G b = receive antenna gain of the BS in dB G m = transmit antenna gain of MS in dB L body = body loss (dB) M fade =log-normal shadow margin (dB) L cable = cable connection loss (dB) L pent = building/vehicle penetration loss (dB) L p = path loss in dB P m = transmit power of MS in dB v f = Voice activity factor E b /I t of Reversed Link:

79. 80 The number of mobiles, are transmitting at a given time in a cell, The pole point or asymptotic cell capacity, Neglecting 1 we can rewrite the equation,

80. 81 Where = power control factor f = interference factor from the neighboring cells. is called the loading factor.

81. Thanks