1G standardNMT-Nordic Mobile Telephone , AMPS-Advanced Mobile Phone System & TACS -Total Access Communications System
Three primary benefits of 2G networks over their predecessors were that phone conversations were digitally encrypted; 2G systems were significantly more efficient on the spectrum allowing for far greater mobile phone penetration levels; and 2G introduced data services for mobile, starting with SMS text messages.
2G TDMA –Time division multiple access , PDC – Personal digital cellular CDMA – code division multiple access2.5 G GPRS was the first step towards evolution of GSM to 3G.2.75 G – EDGE is introduced which provides higher data rates than GPRS. It uses 8PSK coding .
An analogy to the problem of multiple access is a room (channel) in which people wish to talk to each other simultaneously. To avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division), or speak in different languages (code division). CDMA is analogous to the last example where people speaking the same language can understand each other, but other languages are perceived as noise and rejected. Similarly, in radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can communicate.
Also called digital AMPS.PDC – Private digital cellular.
Packet switching data transport is introduced in GPRS.EDGE is introduced in 2.75G.
EDGE is standardized by 3GPP as part of the GSM family.Through the introduction of sophisticated methods of coding and transmitting data, EDGE delivers higher bit-rates per radio channel, resulting in a threefold increase in capacity and performance compared with an ordinary GSM/GPRS connection.EDGE can be used for any packet switched application, such as an Internet connection.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). Peak bit-rates of up to 1Mbit/s and typical bit-rates of 400kbit/s can be expected.
WCDMA – wide band code division multiple access.CDMA2000 1x – Evolution of CDMAone towards 3GCDMA2000 1x EV/DO – 3G technology for CDMA. HSDPA/HSUPA – Upgradation of UMTS.UMTS – 3G mobile cellular technology for GSM. Data rates 7.2 Mbit/s.HSPA+ - provides higher data rates of 84 Mbit/s. Uses MIMO technology and 64QAM.
The 3G standard in 3GPP WCDMAThe 3G standard in 3GPP2 is CDMA2000
EVDO – evolution data only system..
Latency- time b/w ip and op
EPS – evolved packet systemE-UTRAN – evolved UMTS terrestrial Radio access networkEPC –Evolved packet coreSAE- system architecture evolution
Why to have LTE system and to reconsider architecture of system based on GSM only after a decade of introducing 3G/UMTS n/w ?The answer is the fact that the world is different from what was ten years ago. Fixed broadband is now ubiquitous with multimegabit speed at reasonable cost but wireless broadband is today’s mobile experience. Number of wireless subscribers are increasing at a rapid rate. This provides a great complement to operators to introduce mobile broadband service with greater capacity and high speed on both uplink and downlink.
In spatial multiplexing, a high rate signal is split into multiple lower rate streams and each stream is transmitted from a different transmit antenna in the same frequency channel.
Due to orthogonal property of sub-carriers , they do not interfere with one another. Hence cross talk between sub-carriers is eliminated.
Uplink supports BPSK, QPSK, 8PSK, and 16QAM.
E-UTRAN - Evolved
HSS (Home Subscriber Server): The HSS is a central database that contains user-related and subscription-related information.
A new interface called X2 connects the eNBs as a mesh network, enabling direct communication between the elements and eliminating the need to funneldata back and forth through a radio network controller (RNC).
EPS only provides a bearer path of a certain QoS, control of multimedia applications is provided by the IP Multimedia Subsystem (IMS)
Non-access stratum (NAS) is a functional layer in the wireless telecom protocol stack between core network and user equipment. The layer supports signalling and traffic between those two elements.Access Stratum (AS) is a functional layer in the Wireless Telecom protocol stack between Radio Network and User Equipment. The radio network is also called access network.
eNB and UE have control plane and data plane protocol layers as shown in following figure.
ARQ – Automatic repeat request. It is an error control mechanism.
(MBMS), a relatively new technology for broadcasting content such as digital TV to UE using point-to-multi-point connections.
LTE bands between 1 & 22 are for paired spectrum, i.e. FDD, and LTE bands between 33 & 40 are for unpaired spectrum, i.e. TDD.
if a linear receiver is used. This means that Ns streams can be transmitted in parallel, ideally leading to an Ns increase of the spectral efficiency (the number of bits per second and per Hz that can be transmitted over the wireless channel). The practical multiplexing gain can be limited by spatial correlation, which means that some of the parallel streams may have very weak channel gains.
In most cases, only partial CSI is available at the transmitter because of the limitations of the feedback channelA precoding matrix W is used to precode the symbols in the vector to enhance the performance. The column dimension Ns of W can be selected smaller than Nt which is useful if the system requires Ns~= Nt streams because of several reasons. Examples of the reasons are as follows: either the rank of the MIMO channel or the number of receiver antennas is smaller than the number of transmit antennas.
The MAC sub-layer acts as an interface between the Logical Link Control (LLC) sublayer and the network's physical layerThe Media Access Control (MAC) data communication protocol sub-layer, also known as the Medium Access Control, is a sublayer of the Data Link Layer specified in the seven-layer OSI model (layer 2), and in the four-layer TCP/IP model (layer 1)
WiMAX (Worldwide Interoperability for Microwave Access)
FIXED :The primary application was for high-speed fibre access solutions using high frequency line-of-sight (LOS) fixed wireless connections.MOBILE:Mobile communication is more complex than fixed communication. The technology must be able to hand off a wireless connection from one base station to another while the user is moving, without dropping the connection.
A channel is a division in a transmission medium so that it can be used to send multiple streams of information.Access network is that portion of the network between the customer premise and the network operator's point of presence.
WiMAX base station on the tower communicates wirelessly with the WiMAX subscriber station located inside the house.
The mobile WiMAX air interface utilizes Orthogonal Frequency Division Multiple Access (OFDMA) as the radio access method.
Prof. N P GAJJAR EC DEPARTMENTINSTITUTE OF TECHNOLOGY NIRMA UNIVERSITY email@example.com 1
History Introduction to LTE LTE specification MIMO and different input output schemes OFDMA and SC-FDMA 2
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
Mobile radio telephoneTechniques: PTT : Push To Talk MTS: Mobile Telephone Services, through operator IMTS improved MTS, no operator AMTS – Advanced Mobile Telephone System. 4
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
Digital encrypting of all telephone calls Launched “SMS” data services for mobile More efficient 2 techniques: TDMA and CDMA 6
2G systems –• GSM• CDMA 2G systems were primarily designed • To support voice communication • Data transmission 7
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
Uplink transmissions should be of low peak signal due to the limited transmission power at the user equipment (UE). 46
Introduction LTE Architecture and Network LTE Radio Interface Architecture and different parameters MIMO Spatial Multiplexing 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
The LTE network architecture is designed with the following goals. Supporting packet- Quality of serviceswitched traffic with (QoS) Minimal latency seamless mobility 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
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
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
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
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
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
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
Mobility anchor point for inter eNB handovers Termination of user-plane packets for paging reasons Switching of user plane for UE mobility 64
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
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
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
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
It includes• Radio Access Modes• Transmission Bandwidth• Supported Frequency Bands• Peak single user data rates and UE capabilities 70
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
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
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
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
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
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
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
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
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
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
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
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
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
Introduction of WiMAX Back Ground How WIMAX works ? WIMAX feature Advantages of WIMAX Channel Access Comparison of LTE and WIMAX 98
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
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
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
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 providers (ISP) network through fibre optic cables. 107
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
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
Uplink and Downlink Transmissions Duplexing TDD and FDD 111
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
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
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
According to WiMax Forum it supports 5 classes of applications:1. Multi-player Interactive Gaming.2. VOIP and Video Conference3. Streaming Media4. Web Browsing and Instant Messaging5. Media Content Downloads 116
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
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
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
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
Parameter LTE Mobile WiMAX Rel 1.5Duplex FDD and TDD FDD and TDDFrequency Band for 2000 MHz 2500 MHzPerformance AnalysisChannel BW Up to 20 MHz Up to 20 MHzDownlink OFDMA OFDMAUplink SC-FDMA OFDMADL Spectral Efficiency1 1.57 bps/Hz/Sector 1.59 bps/Hz/Sector (2x2) MIMO2 (2x2) MIMOUL Spectral Efficiency1 0.64 bps/Hz/Sector 0.99 bps/Hz/Sector (1x2) SIMO2 (1x2) SIMOMobility Support Target: Up to 350 km/hr Up to 120 km/hrFrame Size 1 millisec 5 millisecHARQ Incremental Redundancy Chase CombiningLink Budget Typically limited by Mobile Device Typically limited by Mobile DeviceAdvanced Antenna DL: 2x2, 2x4, 4x2, 4x4 DL: 2x2, 2x4, 4x2, 4x4Support UL: 1x2, 1x4, 2x2, 2x4 UL: 1x2, 1x4, 2x2, 2x4 122
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