The document provides an overview of the history and evolution of mobile communication technologies from 1G to 4G. It discusses the key characteristics of each generation including 1G which used analog signals for voice calls only, 2G which added digital signaling and SMS, 3G which aimed to provide higher data rates but did not meet expectations, and 4G technologies like LTE and WiMAX that use OFDMA and provide significantly higher broadband speeds. It also covers concepts like MIMO, OFDMA, and SC-FDMA used in 4G networks.

1. Prof. N P GAJJAR
EC DEPARTMENT
INSTITUTE OF TECHNOLOGY
NIRMA UNIVERSITY
npgajjar@yahoo.com
1

2.  History
 Introduction to LTE
 LTE specification
 MIMO and different input output schemes
 OFDMA and SC-FDMA
2

3.  The 0th generation ( 0G).
 The first generation (1G) analog systems
 The second generation (2G) digital systems.
 The Third generation (3G) systems.
 The Fourth generation (4G) systems.
3

4.  Mobile radio telephoneTechniques:
 PTT : Push To Talk
 MTS: Mobile Telephone Services, through
operator
 IMTS improved MTS, no operator
 AMTS – Advanced Mobile Telephone System.
4

5.  Wireless telephone technology
 Voice during call was modulated @ 150 MHz
carrier using Analog modulation.
 Standards
NMT: Nordic Mobile Telephony
AMPS: Advanced Mobile Phone Systems
NTT: Nippon Telegraph and Telephone
TACS: Total Access Communication Systems
5

6.  Digital encrypting of all telephone calls
 Launched “SMS” data services
for mobile
 More efficient
 2 techniques:
TDMA and CDMA
6

7. 2G systems –
• GSM
• CDMA
2G systems were
primarily designed
• To support voice
communication
• Data transmission
7

8.  TDM
 CDMA
 FDM
8

9.  Channel access method for shared medium
networks
 TDMA is a type of Time-division
multiplexing, with the special point that
instead of having one transmitter connected to
one receiver, there are multiple transmitters
 GSM,PDC and IDEN
9

10.  Digital, circuit switching with full
duplex voice telephony – 2G
 Circuit switched data transport
 Improved Packet data transport via GPRS – 2.5 G
 Packet data transport with enhanced speed -2.75
G
 TDMA and FDMA
 GMSK Gaussian minimum-shift keying
10

11.  Enhanced Data rates for GSM Evolution (EDGE)
 Pre-3G radio technology
 Improved data transmission rates.
 backward-compatible extension of GSM
 threefold increase in capacity and performance compared
with an ordinary GSM/GPRS connection.
 Peak bit-rates of up to 1Mbit/s and typical bit-rates of
400kbit/s can be expected.
 Evolved EDGE continues in Release 7 of the 3GPP standard
providing reduced latency and more than doubled
performance e.g. to complement High-Speed Packet Access
(HSPA)
11

12.  Allows several transmitters to send information
simultaneously over a single communication
channel
 CDMA is a form of spread-spectrum signalling,
since the modulated coded signal has a much
higher data bandwidth than the data being
communicated.
 Standards:
cdmaOne, cdma 2000 1x ,cdma 2000 3x
12

13. 13

14. 14

15.  1G
 Narrow band analogue Network so only voice calls.
 We can contact within premises of nation , No roaming
 2G
 More clarity to the conversation and can send SMS.
 GPRS is not available , No packet data transmission.
 In 2.5G packet data service is available but slow data
rates.
15

16. 16

17.  The ITU-R initiative on IMT-2000 (international
mobile telecommunications 2000) paved the way for
evolution to 3G.
 Requirements
 peak data rate of 2 Mb/s and support for vehicular mobility
were published under IMT-2000 initiative.
 Both GSM and CDMA standards formed their own
separate 3G partnership projects (3GPP and 3GPP2,
respectively) to develop IMT-2000 compliant
standards based on the CDMA technology.
17

18.  GSM 3G (3GPP )-
 Wideband CDMA(WCDMA) because it uses a larger
5MHz bandwidth.
 CDMA ( 3GPP2 )-
 CDMA2000 and it uses 1.25MHz bandwidth.
 5MHz version supporting three 1.25MHz
subcarriers referred to as cdma2000-3x.
18

19.  Problems with 3G
 3G standards did not fulfil its promise of high-speed data
transmissions as the data rates supported in practice were
much lower than that claimed in the standards.
 The 3GPP2 first introduced the HRPD (high rate
packet data) system that supported high speed data
transmission.
 HRPD requires a separate 1.25Mhz for data transmission
and no voice service.
 So it is referred to as cdma-1x EVDO system.
19

20.  The 3GPP introduced HSPA (high speed packet
access) enhancement to the WCDMA system.
 A difference relative to HRPD, however, is that both voice
and data can be carried on the same 5MHz carrier in HSPA.
20

21. 21

22. 22

23. 23

24.  WIMAX –
 IEEE 802 LMSC(LAN/MAN Standard Committee)
introduced the IEEE 802.16e standard for mobile
broadband wireless access.
 Enhancement to an earlier IEEE 802.16 standard for fixed
broadband wireless access.
 Technology - OFDMA (orthogonal frequency division
multiple access)
 Better data rates and spectral efficiency than that provided
by HSPA and HRPD.
 Known as WiMAX (worldwide interoperability for
microwave access) .
24

25.  The introduction of Mobile WiMAX led both 3GPP
and 3GPP2 to develop their own version of beyond
3G systems based on the OFDMA technology and
network architecture similar to that in Mobile
WiMAX.
 The beyond 3G system in 3GPP is called evolved
universal terrestrial radio access (evolved UTRA)
and is also widely referred to as LTE (Long-Term
Evolution) while 3GPP2’s version is called UMB
(ultra mobile broadband).
25

26. 26

27.  LTE is also known as Long Term Evolution and it is
considered a system beyond existing 3G systems.
 The goal of LTE –
 High-data-rate, low-latency and packet-optimized radio
access technology supporting flexible bandwidth
deployments.
 Because of OFDMA and SC-FDMA access
schemes, LTE system supports flexible bandwidth.
 In LTE , uplink access is based on SC-FDMA and
downlink access is based on OFDMA.
27

28.  LTE supports flexible carrier bandwidths, from
1.4MHz up to 20MHz as well as both FDD
(Frequency Division Duplex) and TDD (Time
Division Duplex).
 LTE architecture is referred to as EPS and
comprises the E-UTRAN on the access side and
EPC via SAE ,on the core network side.
28

29. 30

30. 31

31.  Increased downlink and uplink peak data rates.
 Scalable channel bandwidths of 1.4, 3, 5, 10,
15, and 20 MHz in both the uplink and the
downlink.
 Spectral efficiency improvements.
 Sub-5 ms latency for small internet protocol
(IP) packets.
 Optimized Performance.
32

32. 33

33. 34

34. 35

35.  SISO –
 Standard transmission mode.
 Single transmitter , single receiver.
 SIMO –
 Single transmitter , multiple receiver.
 It aids received data integrity , where signal to
noise ratio is poor due to multipath fading.
 MISO –
 Multiple transmitter , single receiver.
 The transmitters send the same underlying user
data, but in different parts of the RF frequency
space.
36

36.  Multiple transmitter , multiple receiver.
 LTE provides multiple access and that is
explained using concept of MIMO.
 MIMO is also known as spatial multiplexing.
 MIMO is required to increase high band width
application such as streaming video.
 Multiple antennas improve capacity.
37

37. 38

38.  OFDMA –
 It is FDM used as a digital multi carrier modulation
method. A large number of closely-spaced orthogonal
sub-carriers are used to carry data.
 The data is divided into several parallel data channels.
Each sub-carrier is modulated with a conventional
modulation scheme such as QAM or PSK at a lower
rate.
 Total data rates similar to single carrier modulation
schemes in the same bandwidth.
 Due to low symbol rate, guard interval can be provided
between symbols and hence ISI can be eliminated.
39

39. 40

40.  SC-FDMA –
 SC-FDMA can be interpreted as a linearly precoded
OFDMA scheme, in the sense that it has an additional
DFT processing preceding the conventional OFDMA
processing.
 In SC-FDMA, multiple access among users is made
possible by assigning different users, different sets of
non-overlapping Fourier-coefficients (sub-carriers).
 A prominent advantage of SC-FDMA over OFDMA is
that its transmit signal has a lower peak-to-average
power ratio (PAPR).
 Due to low PAPR ,it benefits the mobile terminal in
terms of transmit power efficiency.
41

41.  In LTE , OFDMA scheme is used for downlink
access.
 The basic principle of OFDM is to divide the
available spectrum into narrowband parallel
channels referred to as subcarriers and transmit
information on these parallel channels at a
reduced signalling rate.
 The name OFDM comes from the fact that the
frequency responses of the sub channels are
overlapping and orthogonal.
42

42. 43

43.  The multi-path interference problem of
WCDMA increases for larger bandwidths such
as 10MHz – 20MHz required by LTE.
 Difficult to employ multiple 5MHz WCDMA
carriers to support 10 and 20MHz bandwidths.
 Lack of flexible bandwidth support as
bandwidths supported can only be multiples of
5MHz and also bandwidths smaller than
5MHz cannot be supported.
44

44.  In LTE , SC-FDMA scheme is used for uplink
access.
 SC-FDMA enables a lower peak-to-average
ratio (PAR) to conserve battery life in mobile
devices.
 Single-carrier FDMA scheme provides
orthogonal access to multiple users
simultaneously accessing the system.
45

45.  Uplink transmissions should be of low peak
signal due to the limited transmission power at
the user equipment (UE).
46

46. 47

47. 48

48.  Introduction
 LTE Architecture and Network
 LTE Radio Interface Architecture and different
parameters
 MIMO Spatial Multiplexing
49

49.  Things which we have covered in review-1
 Basic Introduction of 1G,2G,2.5G,2.75G,3G and
4G.
 Introduction of LTE
 LTE attributes
 LTE uplink and downlink
50

50. The LTE network architecture is
designed with the following goals.
Supporting packet- Quality of service
switched traffic with (QoS) Minimal latency
seamless mobility
51

51.  LTE encompasses the evolution of:
 The radio access through the E-UTRAN
 The non-radio aspects under the term System
Architecture Evolution (SAE)
 Entire system composed of both E-UTRAN and
SAE is called the Evolved Packet System (EPS)
52

52.  The LTE network is comprised of:
 Core Network (CN), called Evolved Packet Core
(EPC) in SAE
 Access network (E-UTRAN)
 CN is responsible for overall control of UE and
establishment of the bearers.
 A bearer is an IP packet flow with a defined QoS
(Quality of service) between the gateway and the
User Terminal (UE).
53

53.  The LTE network is comprised of:
 Core Network (CN), called Evolved Packet Core
(EPC) in SAE
 Access network (E-UTRAN)
 CN is responsible for overall control of UE and
establishment of the bearers.
 A bearer is an IP packet flow with a defined QoS
(Quality of service) between the gateway and the
User Terminal (UE).
54

54.  Main logical nodes in EPC are:
 PDN Gateway (P-GW)
 Serving Gateway (S-GW)
 Mobility Management Entity (MME)
 EPC also includes other nodes and functions, such:
 Home Subscriber Server (HSS)
 Policy Control and Charging Rules Function (PCRF)
 E-UTRAN solely contains the evolved base stations,
called
 eNodeB or eNB
55

55. 56

56. 57

57. 58

58.  All the network interfaces are based on IP protocols.
 The eNBs are interconnected by means of an X2
interface and to the MME/GW entity by means of an
S1 interface.
 The S1 interface supports a many-to-many
relationship between MME/GW and eNBs.
 The functional split between eNB and MME/GW is
shown in following figure,
59

59.  Radio resource management
 IP header compression and encryption
 Selection of MME at UE attachment
 Routing of user plane data towards S-GW
 Scheduling and transmission of paging messages and
broadcast information
 Measurement and measurement reporting
configuration for mobility and scheduling
62

60.  Non-access stratum (NAS) signaling and NAS
signaling security
 Access stratum (AS) security control
 Idle state mobility handling
 EPS bearer control
 Roaming, authentication
 Security negotiations.
 Authorization and P-GW/S-GW selection
63

61.  Mobility anchor point for inter eNB handovers
 Termination of user-plane packets for paging reasons
 Switching of user plane for UE mobility
64

62.  UE IP address allocation
 Per-user-based packet filtering
 Lawful interception
 This was all about functions of different
components in LTE architecture. Now we will see
about LTE Radio Interface and its architecture.
65

63. Control plane protocol
User plane Protocol
66

64.  IP packets are passed through multiple protocol entities:
 Packet Data Convergence Protocol (PDCP)
 IP header compression based on Robust Header
Compression(ROHC)
 Ciphering and integrity protection of transmitted data
 Radio Link Control (RLC)
 Segmentation/Concatenation
 Retransmission handling
 In-sequence delivery to higher layers
67

65.  Medium Access Control (MAC)
 Handles hybrid-ARQ retransmissions
 Uplink and Downlink scheduling at the eNodeB
 Physical Layer (PHY)
 Coding/Decoding
 Modulation/Demodulation (OFDM)
 Multi-antenna mapping
 Other typical physical layer functions
68

66.  RLC offers services to PDCP in the form of radio bearers
 MAC offers services to RLC in the form of logical
channels
 PHY offers services to MAC in the form of transport
channels
69

67. It includes
• Radio Access Modes
• Transmission Bandwidth
• Supported Frequency Bands
• Peak single user data rates and UE
capabilities
70

68.  LTE air interface supports
 FDD and TDD
 Another mode half duplex FDD.
 Half-duplex FDD allows the sharing of hardware
between the uplink and downlink since the uplink and
downlink are never used simultaneously.
 The LTE air interface also supports the multimedia
broadcast and multicast service (MBMS)
71

69.  LTE specifications include variable channel
bandwidths selectable from 1.4 to 20 MHz, with
subcarrier spacing of 15 kHz.
 A subcarrier spacing of 7.5 kHz is also possible.
Subcarrier spacing is constant regardless of the
channel bandwidth.
 The smallest amount of resource that can be allocated
in the uplink or downlink is called a resource block
(RB). An RB is 180 kHz wide and lasts for one 0.5
ms timeslot. Thus involving FDD as well as TDD.
72

70.  The LTE specifications inherit all the frequency
bands defined for UMTS.
 FDD spectrum requires pair bands, one of the uplink
and one for the downlink, and TDD requires a single
band as uplink and downlink are on the same
frequency but time separated. As a result, there are
different LTE band allocations for TDD and FDD. In
some cases these bands may overlap.
 Frequency bands for FDD duplex mode and TDD
duplex mode is shown in following figure.
73

71. 74

72. 75

73.  The estimated peak data rates feasible in ideal
conditions
 100 to 326.4 Mbps on the downlink
 50 to 86.4 Mbps on the uplink
 These rates represent the absolute maximum the
system could support and actual peak data rates will
be scaled back by the introduction of UE categories.
A UE category puts limits on what has to be
supported.
76

74. 77

75. Mimo spatial multiplexing
78

76.  Multiple transmitter , multiple receiver.
 As we have seen in the attributes of LTE that LTE
provides multiple access and that is explained using
concept of MIMO.
 MIMO is also known as spatial multiplexing.
 MIMO is required to increase high band width
application such as streaming video.
 Multiple antennas improve capacity.
79

77. 80

78.  Physical channels: These are transmission channels
that carry user data and control messages.
 Transport channels: The physical layer transport
channels offer information transfer to Medium Access
Control (MAC) and higher layers.
 Logical channels: Provide services for the Medium
Access Control (MAC) layer within the LTE protocol
structure.
87

79.  Downlink:
Physical Broadcast Channel (PBCH): This physical channel carries
system information for UEs requiring to access the network.
 Physical Control Format Indicator Channel (PCFICH)
 Physical Downlink Control Channel (PDCCH) : The main purpose of this
physical channel is to carry mainly scheduling information.
 Physical Hybrid ARQ Indicator Channel (PHICH) : As the name implies,
this channel is used to report the Hybrid ARQ status.
 Physical Downlink Shared Channel (PDSCH) : This channel is used for
unicast and paging functions.
 Physical Multicast Channel (PMCH) : This physical channel carries
system information for multicast purposes.
 Physical Control Format Indicator Channel (PCFICH) : This provides
information to enable the UEs to decode the PDSCH.
88

80.  Uplink:
Physical Uplink Control Channel (PUCCH) : Sends
Hybrid ARQ acknowledgement
 Physical Uplink Shared Channel (PUSCH) : This
physical channel found on the LTE uplink is the
Uplink counterpart of PDSCH
 Physical Random Access Channel (PRACH) : This
uplink physical channel is used for random access
functions.
89

81. Physical layer transport channels offer information transfer to
medium access control (MAC) and higher layers.
 Downlink:
Broadcast Channel (BCH) : The LTE transport channel maps
to Broadcast Control Channel (BCCH)
 Downlink Shared Channel (DL-SCH) : This transport
channel is the main channel for downlink data transfer. It is
used by many logical channels.
 Paging Channel (PCH) : To convey the PCCH
 Multicast Channel (MCH) : This transport channel is used to
transmit MCCH information to set up multicast transmissions.
90

82.  Uplink:
 Uplink Shared Channel (UL-SCH) : This
transport channel is the main channel for uplink
data transfer. It is used by many logical channels.
 Random Access Channel (RACH) : This is used
for random access requirements.
91

83.  Control channels:
Broadcast Control Channel (BCCH) : This control channel
provides system information to all mobile terminals connected to the
eNodeB.
 Paging Control Channel (PCCH) : This control channel is used for
paging information when searching a unit on a network.
 Common Control Channel (CCCH) : This channel is used for
random access information, e.g. for actions including setting up a
connection.
 Multicast Control Channel (MCCH) : This control channel is used
for Information needed for multicast reception.
 Dedicated Control Channel (DCCH) : This control channel is used
for carrying user-specific control information, e.g. for controlling
actions including power control, handover, etc..
92

84.  Traffic channels:
Dedicated Traffic Channel (DTCH) : This traffic
channel is used for the transmission of user data.
 Multicast Traffic Channel (MTCH) : This channel is
used for the transmission of multicast data.
93

85.  LTE for 4G Mobile Broadband by Farooq Khan
 LTE-Advanced Signal Generation and Measurement
Using System Vue Application Note By Jinbiao Xu,
Agilent EEsof EDA
 En.wikipedia.org
 Long Term Evolution (LTE) - A Tutorial by Ahmed
Hamza, Network Systems Laboratory, Simon Fraser
University
96

86.  Introduction of WiMAX
 Back Ground
 How WIMAX works ?
 WIMAX feature
 Advantages of WIMAX
 Channel Access
 Comparison of LTE and WIMAX
98

87.  Emerging technology for broadband wireless access.
Both fixed and mobile broadband wireless Internet
access.
 Defines deployment of broadband wireless
metropolitan area networks.
 Promises high data rates and wide coverage at low
cost.
 Allows accessing broadband Internet even while
moving at vehicular speeds of up to 125 km/h.
99

88.  IEEE 802.16-2004 and IEEE 802.16e-2005 air-
interface standards.
 The WiMAX Forum is developing mobile WiMAX
system profiles that define the mandatory and
optional features of the IEEE standard that are
necessary to build a mobile WiMAX compliant air
interface which can be certified by the WiMAX
Forum.
100

89. 101

90. Types of • Fixed (IEEE 802.16-2004)
• Mobile(IEEE 802.16e-2005)
WIMAX
102

91.  It is a non-profit industry body dedicated to
promoting the adoption of this technology and
ensuring that different vendors’ products will
interoperate.
 It is doing this through developing conformance and
interoperability test plans and certification program.
 WiMAX Forum Certified™ means a service provider
can buy equipment from more than one company and
be confident that everything works together.
103

92. 104

93. Channel ( TDM – FDM )
Access network
Internet access (Dial-up, DSL and cable modem,
Broadband Wireless Access )
point-to-point (PTP) telecommunications
point-to-multipoint (PMP) telecommunications
105

94. 106

95.  WiMAX network consists of
 WiMAX base station
 Multiple WiMAX subscriber stations (fixed or
mobile).
 WiMAX base station is mounted on a tower.
 WiMAX subscriber station is a WiMAX customer
premise equipment (CPE) that is located inside the
house.
 WiMAX base station on the tower is physically wired
to the Internet service provider's (ISP) network
through fibre optic cables.
107

96.  OFDMA
 High Data Rates:
 Peak downlink (DL) data rates up to 128 Mbps
 Peak uplink (UL) data rates up to 56 Mbps
 Quality of Service (QoS):
 Fundamental premise of the IEEE 802.16
architecture is QoS.
108

97.  Scalability :
 It utilizes scalable OFDMA (SOFDMA) and has
the capability to operate in scalable bandwidths
from 1.25 to 20 MHz to comply with various
spectrum allocations worldwide.
 Security:
 Most advanced security features
 Extensible Authentication Protocol (EAP) based
authentication, Advanced Encryption Standard
(AES) based authenticated encryption, and Cipher-
based Message Authentication Code (CMAC) and
Hashed Message Authentication Code (HMAC)
based control message protection schemes.
109

98. 110

99.  Uplink and Downlink Transmissions
 Duplexing
 TDD and FDD
111

100.  Transmission from base station to subscriber stations
is called downlink transmission.
 Transmission from subscriber station to base station
is called uplink transmission.
 Uplink uses Time Division Multiple Access (TDMA).
 Downlink uses Time Division Multiplexing (TDM).
112

101. 113

102.  WiMAX provides broadband speeds for voice, data,
and video applications
 WiMAX provides wide coverage, high capacity at
low cost
 WiMAX enjoys a wide industry support
 WiMAX being a wireless technology, costs less
because there is no need for service providers to
purchase rights-of-way, dig trenches and lay cables.
 WiMAX is standards-based. (IEEE)
114

103.  WiMAX can be used for fixed and mobile broadband
Internet access for data and voice using VoIP (Voice-
over-IP) technology.
 Because WiMAX is based on wireless technology,
and because it is cost-effective, it is easier to extend
broadband Internet access to suburban and rural
areas. This helps in bringing wireless broadband to
the masses and to bridge the digital divide that exists
especially in developing and underdeveloped
countries.
115

104.  According to WiMax Forum it supports 5
classes of applications:
1. Multi-player Interactive Gaming.
2. VOIP and Video Conference
3. Streaming Media
4. Web Browsing and Instant Messaging
5. Media Content Downloads
116

105. Comparison of LTE-WiMAX
117

106.  Both LTE and WiMAX both are considered to be
standards for 4G mobile communication.
 LTE is the most recent in the line of the GSM
broadband network evolvement.
 WiMAX evolved from a Wi-Fi, IP-based
background. IEEE standard 802.16.
118

107. 1. Both use orthogonal frequency division multiple
access (OFDMA) in the downlink. But WiMax
optimizes for maximum channel usage by processing
all the information in a wide channel. LTE, on the
other hand, organizes the available spectrum into
smaller chunks.
119

108. 2. LTE uses single-carrier frequency division multiple
access (SC-FDMA) for uplink signalling, while
WiMax sticks with OFDMA. A major problem with
OFDM-based systems is their high peak-to-average
power ratios. LTE opted for the SC-FDMA
specifically to boost PA efficiency.
3. Although both the IEEE 802.16e standard and the
LTE standard support FDD and TDD, WiMax
implementations are predominantly TDD. LTE seems
to be heading in the FDD direction because it is true
full-duplex operation: Adjacent channels are used for
uplink and downlink.
120

109. Mobile WiMAX
Rel 1.0 Rel 1.5 Rel 2.0
802.16e-2005 802.16e Rev 2 802.16m
IP e2e Network
3GPP IMT-
121 HSPA HSPA+ Advanced
Rel-6 Rel-7 & Rel-8
Ckt Switched Network
LTE & LTE Advanced
IP e2e Network
Mobile WiMAX
time to market
advantage
CDMA-Based OFDMA-Based
2008 2009 2010 2011 2012
121

110. Parameter LTE Mobile WiMAX Rel 1.5
Duplex FDD and TDD FDD and TDD
Frequency Band for 2000 MHz 2500 MHz
Performance Analysis
Channel BW Up to 20 MHz Up to 20 MHz
Downlink OFDMA OFDMA
Uplink SC-FDMA OFDMA
DL Spectral Efficiency1 1.57 bps/Hz/Sector 1.59 bps/Hz/Sector
(2x2) MIMO2 (2x2) MIMO
UL Spectral Efficiency1 0.64 bps/Hz/Sector 0.99 bps/Hz/Sector
(1x2) SIMO2 (1x2) SIMO
Mobility Support Target: Up to 350 km/hr Up to 120 km/hr
Frame Size 1 millisec 5 millisec
HARQ Incremental Redundancy Chase Combining
Link Budget Typically limited by Mobile Device Typically limited by Mobile Device
Advanced Antenna DL: 2x2, 2x4, 4x2, 4x4 DL: 2x2, 2x4, 4x2, 4x4
Support UL: 1x2, 1x4, 2x2, 2x4 UL: 1x2, 1x4, 2x2, 2x4
122

111.  Introduction to WiMax and Broadband Access
Technologies By M. Farhad Hussain
 WiMAX - An Introduction by N. Srinath (Department
of Computer Science and Engineering, Indian
Institute of Technology Madras)
 WiMAX INTRODUCTION by Paul DeBeasi
 Introduction to mobile WiMAX Radio Access
Technology by Dr. Sassan Ahmadi (Wireless
Standards and Technology, Intel Corporation)
123

112. 124