Key Technologies for the Next Generation Wireless

8/14/2019 Key Technologies for the Next Generation Wireless

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IPv6 support 8

3. Long Term Evolution Advanced 9

Overview 9

Downlink 10

Uplink 11

4. WiMAX 12

Definitions 13

Uses 13

Broadband access 14

Mobile handset applications 14

IPTV over WiMAX 15

Comparison with Wi-Fi 15

Spectrum allocation issues 16

Spectral efficiency 17

Silicon implementations 18

5. Digital Multimedia Broadcasting 19

S-DMB 19

T-DMB 19

6. Software-defined radio 21

7. Smart antenna 22

Direction of arrival (DOA) estimation 22

Beamforming 22

Types of smart antennas 22

Extension of smart antennas 23

8. Applications 24

9. Conclusion 26

10.Reference 27


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Table of Figures

Figure 1:Application and Transport Technology Trends 1

Figure 2:Overlay of 4G 6Figure 3:WiMAX base station equipment with asector antenna and wireless modem ontop 12

Figure 4:A pre-WiMAX CPE of a 26 km (16 mi) connection mounted 13 meters (43 ft) abovethe ground (2004, Lithuania). 12

Figure 5:Illustration of a WiMAX MIMO board 15

Figure 6:DMB broadcasting in Mexico on a Zonda TV20 Smartphone 20

1. Introduction

In a world of fast changing technology, there is a rising requirement for people tocommunicate and get connected with each other and have appropriate and timely access toinformation regardless of the location of the each individuals or the information. Theincreasing demands and requirements for wireless communication systems ubiquity have ledto the need for a better understanding of fundamental issues in communication theory andelectromagnetic and their implications for the design of highly-capable wireless systems. Incontinuous development of mobile environments, the major service providers in the wirelessmarket kept on monitoring the growths of 4th generation (4G) mobile technology. 2G and 3Gare well-established as the mainstream mobile technology around the world. 3G is stumblingto obtain market share for a different reasons and 4G is achieving some confidence.


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Figure 1: Application and Transport Technology Trends

Next generation wireless is mainly about increasing the rate of data transmission.

There are different technologies for achieving this goal like the 4G, WiMax, LTE, Smart

Antenna, SDR and DMB.

4G refers to the Fourth Generation of cellular wireless standards. It is a successorto3G and2G standards, with the aim to provide a wide range of data rates up to ultra-broadband (gigabit-speed) Internet access to mobile as well as stationary users. Although 4Gis a broad term that has had several different and more vague definitions, this article uses 4Gto refer to IMT Advanced (International Mobile Telecommunications Advanced), as definedby ITU-R.

LTE Advanced (Long-term-evolution Advanced) is a candidate for IMT-Advancedstandard, formally submitted by the 3GPPorganization to ITU-T in the fall 2009, andexpected to be released in 2011. The target of 3GPP LTE Advanced is to reach and surpassthe ITU requirements. LTE Advanced should be compatible with first release LTEequipment, and should share frequency bands with first release LTE.

The Mobile WiMAX(IEEE 802.16e-2005) mobile wireless broadband access (MWBA)standard is sometimes branded 4G, and offers peak data rates of 128 Mbit/s downlink and 56Mbit/s uplink over 20 MHz wide channels. The IEEE 802.16m evolution of 802.16e is underdevelopment, with the objective to fulfill the IMT-Advanced criteria of 1000 Mbit/s forstationary reception and 100 Mbit/s for mobile reception.
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Digital Multimedia Broadcasting(DMB) is a digitalradio transmission technologydeveloped by South Korea as part of the nationalIT project for sending multimedia such asTV, radio and data castingto mobile devices such as mobile phones. This technology,sometimes known as mobile TV, should not be confused with Digital AudioBroadcastingwhich was developed as a research project for the European Union. DMB was

originally developed in South Korea as the next generation digital technology to replace theFM radio. The world's first official mobile TV service started in South Korea in May 2005,although trials were available much earlier.

SDR(software-defined radio) is one form of open wireless architecture (OWA). Since 4Gis a collection of wireless standards, the final form of a 4G device will constitute variousstandards. This can be efficiently realized using SDR technology, which is categorized to thearea of the radio convergence.

Smart antennas (also known as adaptive array antennas, multiple antennas andrecently MIMO) are antenna arrayswith smart signal processing algorithms used to identifyspatial signal signature such as thedirection of arrival (DOA) of the signal, and use it tocalculate beamformingvectors, to track and locate the antenna beam on the mobile/target.The antenna could optionally be any sensor.

2. 4GA 4G cellular system must have target peak data rates of up to approximately 100 Mbit/s forhigh mobility such as mobile access and up to approximately 1 Gbit/s for low mobility suchas nomadic/local wireless access, according to the ITU requirements. Scalablebandwidths upto at least 40 MHz should be provided. A 4G system is expected to provide a comprehensiveand secure all-IP based solution where facilities such as IP telephony, ultra-broadbandInternet access, gaming services and HDTV streamed multimedia may be provided to users.

On the other hand 4G visions take into account installed base and past investments. It hasfaster data transmission and higher bit rate and bandwidth, allow more business applicationsand commercialization. Has advantage for personalized multimedia communication tools.

Technology Companies with 4G networks are knocking on the door and mobile operators arebeginning to answer. 4G networks and Next Generation Networks (NGNs) are becoming fastand very cost-effective solutions for those wanting an IP built high-speed data capacities inthe mobile network.IP is pushing its way into the mobile wireless market, said Visant Strategies Senior AnalystAndy Fuertes, author of The Road to 4G and NGN: Wireless IP Migration Paths. By 2010,the just-published study finds, there will be 113 million NGN and 4G users, with the marketstarting to take effect 2006 and 2007.

Objectives

4G is being developed to accommodate theQoSand rate requirements set by furtherdevelopment of existing 3G applications like wireless broadband access, MultimediaMessaging Service(MMS), video chat,mobile TV, but also new serviceslike HDTV content, minimal services like voice and data, and other services that utilize
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bandwidth. It may be allowed roaming with wireless local area networks, and be combinedwithdigital video broadcastingsystems.

The 4G working group has defined the following as objectives of the 4G wirelesscommunication standard:

Flexible channel bandwidth, between 5 and 20 MHz, optionally up to 40 MHz.

A nominal data rate of 100 Mbit/s while the client physically moves at high speeds relative tothe station, and 1 Gbit/s while client and station are in relatively fixed positions as defined bythe ITU-R,

A data rate of at least 100 Mbit/s between any two points in the world,

Peaklink spectral efficiencyof 15 bit/s/Hz in the downlink, and 6.75 bit/s/Hz in the uplink

(meaning that 1000 Mbit/s in the downlink should be possible over less than 67 MHzbandwidth)

System spectral efficiencyof up to 3 bit/s/Hz/cell in the downlink and 2.25 bit/s/Hz/cell forindoor usage. Smoothhandoffacross heterogeneous networks, Seamless connectivity andglobal roamingacross multiple networks, High quality of service for next generationmultimedia support (real time audio, high speed data, HDTV video content, mobile TV, etc)Interoperability with existing wireless standards, and

An all IP,packet switchednetwork.

4G features

According to the members of the 4G working group, the infrastructure and the terminals of4G will have almost all the standards from 2G to 4G implemented. Although legacy systemsare in place to adopt existing users, the infrastructure for 4G will be only packet-based (all-IP). Some proposals suggest having an open Internet platform. Technologies considered to beearly 4G include: Flash-OFDM, the 802.16e mobile version ofWiMax (also knownas WiBro in South Korea), and HC-SDMA.
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Figure 2: Overlay of 4G

Access schemesAs the wireless standards evolved, the access techniques used also exhibited increase inefficiency, capacity and scalability. The first generation wireless standards usedplain TDMA and FDMA. In the wireless channels, TDMA proved to be less efficient inhandling the high data rate channels as it requires large guard periods to alleviate themultipath impact. Similarly, FDMA consumed more bandwidth for guard to avoid intercarrier interference. So in second generation systems, one set of standard used thecombination of FDMA and TDMA and the other set introduced an access schemecalled CDMA. Usage of CDMA increased the system capacity, but as a drawback placed asoft limit on it rather than the hard limit (i.e. a CDMA network will not reject new clientswhen it approaches its limits, resulting in a denial of service to all clients when the networkoverloads). Data rate is also increased as this access scheme (providing the network is not
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reaching its capacity) is efficient enough to handle the multipath channel. This enabled thethird generation systems, such as IS-2000, UMTS, HSXPA,1xEV-DO, TD-CDMA and TD-SCDMA, to use CDMA as the access scheme. However, the issue with CDMA is that itsuffers from poor spectral flexibility and computationally intensive time-domain equalization(high number of multiplications per second) for wideband channels.

Recently, new access schemes like Orthogonal FDMA(OFDMA),Single CarrierFDMA (SC-FDMA), Interleaved FDMA andMulti-carrier CDMA(MC-CDMA) are gainingmore importance for the next generation systems. These are based on efficient FFT algorithmand frequency domain equalization, resulting lower number of multiplications per second.They also make it possible to control the bandwidth and form the spectrum in a flexible way.However, they require advanced dynamic channel allocation and traffic adaptive scheduling.

The other important advantage of the above mentioned access techniques are that theyrequire less complexity for equalization at the receiver. This is an added advantage especiallyin the MIMO environments since the spatial multiplexingtransmission of MIMO systemsinherently requires high complexity equalization at the receiver.

IPv6 supportUnlike 3G, which is based on two parallel infrastructures consistingofcircuit switchedandpacket switchednetwork nodes respectively,4G will be based on packet switchingonly. This will requirelow-latencydata transmission.

By the time that 4G is deployed, the process ofIPv4 address exhaustion is expected to be in

its final stages. Therefore, in the context of 4G, IPv6support is essential in order to support alarge number of wireless-enabled devices. By increasing the number ofIP addresses, IPv6removes the need for Network Address Translation (NAT), a method of sharing a limitednumber of addresses among a larger group of devices, although NAT will still be required tocommunicate with devices that are on existingIPv4networks.

As of June 2009,Verizon has posted specificationsthat require any 4G devices on itsnetwork to support Ipv6.

3. Long Term Evolution AdvancedLTE (Long Term Evolution) is the project name of a new high performance air interface

for cellular mobile communication systems. It is the last step toward the 4th generation ( 4G)of radio technologies designed to increase the capacity and speed of mobile telephonenetworks. Where the current generation of mobile telecommunication networks arecollectively known as 3G (for "third generation"), LTE is marketed as 4G. However, it doesnot fully comply with theIMT Advanced 4G requirements. Most major mobile carriers in theUnited States and several worldwide carriers have announced plans to convert their networksto LTE beginning in 2009. The world's first publicly available LTE-service was openedby Telia Sonera in the two Scandinavian capitals StockholmandOsloon the 14th of
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December 2009. LTE is a set of enhancements to the Universal Mobile TelecommunicationsSystem (UMTS) which will be introduced in 3rd Generation Partnership Project (3GPP)Release 8. Much of 3GPP Release 8 will focus on adopting 4G mobile communicationstechnology, including an all-IPflat networking architecture. On August 18, 2009,the European Commissionannounced it will invest a total of 18 million into researching the

deployment of LTE and 4G candidate systemsLTE Advanced.While it is commonly seen as a mobile telephone or common carrier development, publicsafety agencies in the US have also endorsed LTE as the preferred technology for the new700 MHz public-safety radio band. Agencies in some areas have filed for waivers hoping touse the 700 MHz spectrum with other technologies in advance of the adoption of anationwide standard.

Overview

The LTE specification provides downlink peak rates of at least 100 Mbps, an uplink of atleast 50 Mbps and RANround-trip timesof less than 10 ms. LTE supports scalablecarrierbandwidths, from 20 MHz down to 1.4 MHz and supports both frequency divisionduplexing (FDD) and time division duplexing (TDD).

Part of the LTE standard is theSystem Architecture Evolution, a flatIP-basednetworkarchitecture designed to replace the GPRS Core Networkand ensure support for, andmobility between, some legacy or non-3GPP systems, for example GPRS and WiMax respectively.

The main advantages with LTE are high throughput, low latency, plug andplay, FDD and TDD in the same platform, an improved end-user experience and a simplearchitecture resulting in low operating costs. LTE will also support seamless passing to celltowers with older network technology such as GSM, CDMA One,W-CDMA (UMTS),andCDMA2000.

While 3GPP Release 8 is an unratified, formative standard, much of the Release addressesupgrading 3G UMTS to 4G mobile communications technology, which is essentially amobile broadband system with enhanced multimedia services built on top.

DownlinkLTE uses OFDM for the downlink that is, from the base station to the terminal. OFDMmeets the LTE requirement for spectrum flexibility and enables cost-efficient solutions forvery wide carriers with high peak rates. It is a well-established technology, for example instandards such as IEEE 802.11a/g, 802.16, HIPERLAN-2, DVB and DAB.

In the time domain there is a radio frame that is 10 ms long and consists of 10 sub frames of1ms each. Every sub frame consists of 2 slots where each slot is 0.5 ms. The subcarrierspacing in the frequency domain is 15 KHz. Twelve of these subcarriers together (per slot) iscalled a resource block so one resource block is 180 KHz. 6 Resource blocks fit in a carrierof 1.4 MHz and 100 resource blocks fit in a carrier of 20 MHz.

In the downlink there are three main physical channels. The Physical Downlink SharedChannel (PDSCH) is used for all the data transmission, the Physical Multicast Channel
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(PMCH) is used for broadcast transmission using a Single Frequency Network and thePhysical Broadcast Channel (PBCH) is used to send most important system informationwithin the cell. Supported modulation formats on the PDSCH areQPSK, 16QAMand 64QAM.

ForMIMO operation, a distinction is made between single user MIMO, for enhancing one

user's data throughput, and multi userMIMO for enhancing the cell throughput.

UplinkIn the uplink, for the Physical Uplink Shared channel (PUSCH) only, LTE uses a pre-codedversion of OFDM called Single Carrier Frequency Division Multiple Access (SC-FDMA).This is to compensate for a drawback with normal OFDM, which has a very high peak-to-average power ratio (PAPR). High PAPR requires expensive and inefficient power amplifierswith high requirements on linearity, which increases the cost of the terminal and drains thebattery faster. SC-FDMA solves this problem by grouping together the resource blocks in away that reduces the need for linearity, and so power consumption, in the power amplifier. Alow PAPR also improves coverage and the cell-edge performance.

In the uplink there are three physical channels. While the Physical Random Access Channel(PRACH) is only used for initial access and when the UE is not uplink synchronized, all thedata is sent on the Physical Uplink Shared Channel (PUSCH). If there is no data to betransmitted on Uplink for an UE, control information would be transmitted on the PhysicalUplink Control Channel (PUCCH). Supported modulation formats on the uplink data channelare QPSK, 16QAM and 64QAM.

4. WiMAXWiMAX, meaning Worldwide Interoperability for Microwave Access, isatelecommunications technology that provides wireless transmission of data using a varietyof transmission modes, frompoint-to-multipointlinks to portable and fully mobile internetaccess. The technology provides up to 10 Mbps broadband speed without the need for cables.The technology is based on the IEEE 802.16 standard (also calledBroadband WirelessAccess). The name "WiMAX" was created by the WiMAX Forum, which was formed inJune 2001 to promote conformity and interoperability of the standard. The forum describesWiMAX as "a standards-based technology enabling the delivery oflast mile wirelessbroadband access as an alternative to cable and DSL".
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Figure 3:WiMAX base station equipment with asector antenna and wireless modem on top

Figure 4:A pre-WiMAX CPE of a 26 km (16 mi) connection mounted 13 meters (43 ft) above the ground

(2004, Lithuania).

Definitions

The 802.16 standards are sometimes referred to colloquially as "WiMAX", "mobileWiMAX", "802.16d" and "802.16e." Their formal names are as follow:

802.16-2004 is also known as 802.16d, which refers to the working party that has developedthat standard. It is sometimes referred to as "fixed WiMAX," since it has no support formobility.

802.16e-2005, often abbreviated to 802.16e, is an amendment to 802.16-2004. It introducedsupport for mobility, among other things and is therefore also known as "mobile WiMAX".

Uses

The bandwidth and range of WiMAX make it suitable for the following potentialapplications:

Connecting Wi-Fi hotspotsto the Internet.

Providing a wireless alternative to cable and DSL for "last mile"broadband access.

Providing data, telecommunications and IPTV services (triple-play).
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Providing a source of Internet connectivity as part of a businesscontinuity plan. That is, if a business has both a fixed and a wireless Internetconnection, especially from unrelated providers, they are unlikely to be affected bythe same service outage.

Providing portable connectivity.

Broadband access

Companies are evaluating WiMAX forlast mile connectivity. The resulting competition maybring lower pricing for both home and business customers or bring broadband access toplaces where it has been economically unavailable.

WiMAX access was used to assist with communications inAceh, Indonesia, afterthe tsunami in December 2004. All communication infrastructures in the area, otherthan amateur radio, were destroyed, making the survivors unable to communicate withpeople outside the disaster area and vice versa. WiMAX provided broadband access thathelped regenerate communication to and from Aceh.

In addition, WiMAX was donated by Intel Corporationto assist theFCCandFEMA in theircommunications efforts in the areas affected by Hurricane Katrina. In practice, volunteersused mainly self-healing mesh,VoIP, and a satellite uplink combined with Wi-Fi on the locallink.

Mobile handset applications

Sprint Nextelannounced in mid-2006 that it would invest about US$ 5 billion in a WiMAXtechnology build out over the next few years ($5.29 billion in real terms). Since that timeSprint has faced many setbacks, which have resulted in steep quarterly losses. On May7, 2008, Sprint Nextel, Google,Intel,Comcast,Bright House, and Time Warnerannounced apooling of an average of 120 MHz of spectrum and merged withClearwire to form acompany which will take the name Clear. The new company hopes to benefit from combinedservices offerings and network resources as a springboard past its competitors. The cablecompanies will provide media services to other partners while gaining access to the wirelessnetwork as a Mobile virtual network operator. Google will contribute Android handset devicedevelopment and applications and will receive revenue share for advertising and otherservices they provide. Sprint and Clearwire gain a majority stock ownership in the newventure and ability to access between the new Clear and Sprint 3G networks. Some detailsremain unclear including how soon and in what form announced multi-mode WiMAX and3G EV-DO devices will be available. This raises questions that arise for availability ofcompetitive chips that require licensing of Qualcomm's IPR.

IPTV over WiMAXDeploying Internet access and Voice over IP using WiMAX radio access is quite easy. Inorder to have a full triple-play offer, IPTV service has to be added. But it's not straightforward, since the use of IP multicast over a WiMAX radio transmission to carry the IPTVchannels may be a technical challenge. Such commercial services are not yet available, buttrials have been conducted or are underway.

Technical Information
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Figure 5:Illustration of a WiMAX MIMO board

WiMAX refers to interoperable implementations of theIEEE 802.16 wireless-networksstandard, in similarity with Wi-Fi, which refers to interoperable implementations of the IEEE802.11 Wireless LAN standard.

Comparison with Wi-Fi

Comparisons and confusion between WiMAX andWi-Fiare frequent because both arerelated to wireless connectivity and Internet access.

WiMAX is a long range system, covering many kilometers that uses licensed or unlicensedspectrum to deliver a point-to-point connection to the Internet.

Different 802.16 standards provide different types of access, from portable (similar to acordless phone) to fixed (an alternative to wired access, where the end user's wirelesstermination point is fixed in location.)

Wi-Fi uses unlicensed spectrum to provide access to a network.

Wi-Fi is more popular in end user devices.

WiMAX and Wi-Fi have quite different quality of service (QoS)mechanisms:

WiMAX uses a QoS mechanism based on connections between the basestation and the user device. Each connection is based on specific schedulingalgorithms.

Wi-Fi has a QoS mechanism similar to fixed Ethernet, where packets canreceive different priorities based on their tags. For example VoIP traffic may begiven priority over web browsing.

Wi-Fi runs on the Media Access Control's CSMA/CA protocol, which isconnectionless and contention based, whereas WiMAX runs a connection-orientedMAC.

Both802.11 and 802.16 define Peer-to-Peer (P2P)and ad hoc networks, where an end usercommunicates to users or servers on another Local Area Network (LAN)using its accesspointorbase station.
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Spectrum allocation issues

The 802.16 specification applies across a wide swath of the RF spectrum, and WiMAX couldfunction on any frequency below 66 GHz, (higher frequencies would decrease the range of aBase Station to a few hundred meters in an urban environment).

There is no uniform global licensed spectrum for WiMAX, although the WiMAX Forum haspublished three licensed spectrum profiles: 2.3 GHz, 2.5 GHz and 3.5 GHz, in an effort todecrease cost: economies of scale dictate that the more WiMAX embedded devices (such asmobile phones and WiMAX-embedded laptops) are produced, the lower the unit cost. (Thetwo highest cost components of producing a mobile phone are the silicon and the extra radioneeded for each band.) Similareconomy of scalebenefits apply to the production of BaseStations.

In the unlicensed band, 5.x GHz is the approved profile. Telecommunication companies areunlikely to use this spectrum widely other than forbackhaul, since they do not own andcontrol the spectrum.

In the USA, the biggest segment available is around 2.5 GHz, and is already assigned,primarily toSprint NextelandClearwire. Elsewhere in the world, the most-likely bands usedwill be the Forum approved ones, with 2.3 GHz probably being most important in Asia.Some countries in Asia like India and Indonesia will use a mix of 2.5 GHz, 3.3 GHz andother frequencies. Pakistan'sWateen Telecom uses 3.5 GHz.

Analog TV bands (700 MHz) may become available for WiMAX usage, but await thecomplete roll out ofdigital TV, and there will be other uses suggested for that spectrum. Inthe USA the FCCauction for this spectrumbegan in January 2008 and, as a result, thebiggest share of the spectrum went to Verizon Wireless and the next biggest to AT&T. Bothof these companies have stated their intention of supportingLTE, a technology whichcompetes directly with WiMAX. EU commissionerViviane Redinghas suggested re-

allocation of 500800 MHz spectrum for wireless communication, including WiMAX.

WiMAX profiles define channel size, TDD/FDD and other necessary attributes in order tohave inter-operating products. The current fixed profiles are defined for both TDD and FDDprofiles. At this point, all of the mobile profiles are TDD only. The fixed profiles havechannel sizes of 3.5 MHz, 5 MHz, 7 MHz and 10 MHz. The mobile profiles are 5 MHz,8.75 MHz and 10 MHz. (Note: the 802.16 standard allows a far wider variety of channels,but only the above subsets are supported as WiMAX profiles.)

Since October 2007, the Radio communication Sector of the InternationalTelecommunication Union (ITU-R) has decided to include WiMAX technology in the IMT-2000 set of standards. This enables spectrum owners (specifically in the 2.5-2.69 GHz band

at this stage) to use Mobile WiMAX equipment in any country that recognizes the IMT-2000.

Spectral efficiencyOne of the significant advantages of advanced wireless systems such as WiMAX is spectralefficiency. For example, 802.16-2004 (fixed) has a spectral efficiency of 3.7 (bit/s)/Hertz,
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and other 3.54G wireless systems offer spectral efficiencies that are similar to within a fewtenths of a percent. The notable advantage of WiMAX comes from combining SOFDMAwithsmart antenna technologies. This multiplies the effective spectral efficiency throughmultiple reuse and smart network deployment topologies. The direct use of frequencydomain organization simplifies designs using MIMO-AAS compared to CDMA/WCDMA

methods, resulting in more effective systems.

Silicon implementations

A critical requirement for the success of a new technology is the availability of low-costchipsetsand silicon implementations.

Mobile WiMAX has a strong silicon ecosystem with a number of specialized companies producing baseband ICs and integrated RFICs for implementing full-featured MobileWiMAX Subscriber Stations based on the IEEE 802.16e standard. It is notable that most ofthe major semiconductor companies have not developed WiMAX chipsets of their own andhave instead chosen to invest in and/or utilize the well developed products from smallerspecialists or start-up suppliers. These companies include but not limited to Beceem, Sequansand PicoChip. The chipsets from these companies are used in the majority of MobileWiMAX devices.

Intel Corporationis a leader in promoting WiMAX, but has limited its WiMAX chipsetdevelopment and instead chosen to invest in these specialized companies producing siliconcompatible with the various WiMAX deployments throughout the globe.

5. Digital Multimedia BroadcastingIt can operate via satellite (S-DMB) or terrestrial (T-DMB) transmission. DMB has alsosome similarities with the main competing mobile TV standard, DVB-H.

S-DMB

S-DMB (Satellite-DMB) is a hybrid version of the Digital Multimedia Broadcasting. The S-DMB uses the S band (2170-2200 MHz) of IMT-2000 and delivers around 18 channels at128 kbps in 15 MHz. It incorporates a high powergeostationary satellite, the MBSat 1. Foroutdoor and light indoor coverage is integrated with a terrestrial repeater (low power gap-filler) network for indoor coverage in urban areas.

A similar architecture is also used in XM Satellite Radio,Sirius Satellite Radio,DVB-SH and ETSI Satellite Digital Radio(SDR).

T-DMB

T-DMB is made for transmissions on radio frequencybands band III (VHF) andL (UHF),for terrestrial. Because the United States and Canada still allocatethe first band for televisionbroadcasting (VHF channels 7 to 13) and the United States reserves the L band for military
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applications, DMB is still unavailable in North America. Qualcomm's Media FLO isaproprietarysystem used there instead, using UHF channel 55. In Japan,1segis the standard,using ISDB.

T-DMB usesMPEG-4 Part 10(H.264) for the video and MPEG-4 Part 3 BSAC orHE-AAC V2 for the audio. The audio and video is encapsulated in anMPEG transport

stream (MPEG-TS). The stream is forward error corrected by Reed Solomonencoding andthe parity word is 16 bytes long. There is convolutioninterleaving made on this stream andthe stream is broadcast in data stream mode on DAB. In order to diminish the channel effectssuch as fading and shadowing, DMB modem uses OFDM-DQPSKmodulation. A single-chipT-DMB receiver is also provided by an MPEG transport streamdemultiplexer. DMBhas several applicable devices such as mobile phone, portable TV, PDAandtelemetricdevices for automobiles.

T-DMB is an ETSI standard (TS 102 427 and TS 102 428). As of December 14,2007, ITU formally approved T-DMB as the global standard, along with three otherstandards, like DVB-H, OneSeg, and Media FLO.

Figure 6:DMB broadcasting in Mexico on a Zonda TV20 Smartphone

6. Software-defined radioA software-defined radio system, orSDR, is a radiocommunication system wherecomponents that have typically been implemented in hardware (e.g. mixers, filters,amplifiers, modulators/demodulators, detectors, etc.) are instead implemented using softwareon a personal computer or embedded computing devices. While the concept of SDR is notnew, the rapidly evolving capabilities of digital electronics are making practical manyprocesses that were once only theoretically possible.

A basic SDR system may consist of a personal computerequipped with a sound card, orotheranalog-to-digital converter, preceded by some form ofRF front end. Significantamounts ofsignal processingare handed over to the general-purpose processor, rather thanbeing done in special-purpose hardware. Such a design produces a radio that can receive andtransmit widely different radio protocols (sometimes referred to as a waveforms) based solelyon the software used.
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Software radios have significant utility for the military and cell phoneservices, both of whichmust serve a wide variety of changing radio protocols in real time.

In the long term, software-defined radios are expected by proponents to become thedominanttechnologyin radio communications. SDRs, along with software definedantennas are the enablers of the cognitive radio.

Ideal concept

The idealreceiverscheme would be to attach an analog-to-digital converter to an antenna.A digital signal processorwould read the converter, and then its software would transformthe stream of data from the converter to any other form the application requires.

An ideal transmitterwould be similar. A digital signal processor would generate a stream ofnumbers. These would be sent to a digital-to-analog converterconnected to a radio antenna.

7. Smart antennaSmart antenna techniques are used notably in acoustic signal processing, track andscan RADAR,radio astronomyandradio telescopes, and mostly in cellular systemslikeW-CDMA andUMTS.

Smart antennas have two main functions: DOA estimation andBeamforming.

Direction of arrival (DOA) estimation

The smart antenna system estimates the direction of arrival of the signal, using techniquessuch as MUSIC (Multiple Signal Classification),estimation of signal parameters viarotational invariance techniques(ESPRIT) algorithms, Matrix Pencil method or one of theirderivatives. They involve finding a spatial spectrumof the antenna/sensor array, andcalculating the DOA from the peaks of this spectrum. These calculations are computationally

intensive.

Matrix Pencil is very efficient in case of real time systems, and under the correlated sources.

Beamforming

Beamformingis the method used to create the radiation patternof the antenna array byadding constructively the phases of the signals in the direction of the targets/mobiles desired,and nulling the pattern of the targets/mobiles that are undesired/interfering targets. This canbe done with a simple FIRtapped delay line filter. The weights of the FIR filter may also bechanged adaptively, and used to provide optimal beamforming, in the sense that it reducesthe MMSE between the desired and actual beam pattern formed. Typical algorithms are

the steepest descent, and LMS algorithms.

Types of smart antennas

Two of the main types of smart antennas include switched beam smart antennas andadaptivearraysmart antennas. Switched beam systems have several available fixed beam patterns. Adecision is made as to which beam to access, at any given point in time, based upon therequirements of the system. Adaptive arrays allow the antenna to steer the beam to any
http://en.wikipedia.org/wiki/Cell_phonehttp://en.wikipedia.org/wiki/Technologyhttp://en.wikipedia.org/wiki/Technologyhttp://en.wikipedia.org/wiki/Radio_communicationshttp://en.wikipedia.org/wiki/Radio_communicationshttp://en.wikipedia.org/wiki/Software_defined_antennahttp://en.wikipedia.org/wiki/Software_defined_antennahttp://en.wikipedia.org/wiki/Cognitive_radiohttp://en.wikipedia.org/wiki/Cognitive_radiohttp://en.wikipedia.org/wiki/Receiver_(radio)http://en.wikipedia.org/wiki/Receiver_(radio)http://en.wikipedia.org/wiki/Receiver_(radio)http://en.wikipedia.org/wiki/Digital_signal_processorhttp://en.wikipedia.org/wiki/Transmitterhttp://en.wikipedia.org/wiki/Digital-to-analog_converterhttp://en.wikipedia.org/wiki/RADARhttp://en.wikipedia.org/wiki/RADARhttp://en.wikipedia.org/wiki/Radio_astronomyhttp://en.wikipedia.org/wiki/Radio_telescopehttp://en.wikipedia.org/wiki/Radio_telescopehttp://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/W-CDMAhttp://en.wikipedia.org/wiki/W-CDMAhttp://en.wikipedia.org/wiki/W-CDMAhttp://en.wikipedia.org/wiki/UMTShttp://en.wikipedia.org/wiki/UMTShttp://en.wikipedia.org/wiki/Beamforminghttp://en.wikipedia.org/wiki/Beamforminghttp://en.wikipedia.org/wiki/Beamforminghttp://en.wikipedia.org/wiki/Multiple_signal_classificationhttp://en.wikipedia.org/wiki/Estimation_of_signal_parameters_via_rotational_invariance_techniqueshttp://en.wikipedia.org/wiki/Estimation_of_signal_parameters_via_rotational_invariance_techniqueshttp://en.wikipedia.org/wiki/Estimation_of_signal_parameters_via_rotational_invariance_techniqueshttp://en.wikipedia.org/w/index.php?title=Spatial_spectrum&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Spatial_spectrum&action=edit&redlink=1http://en.wikipedia.org/wiki/Beamforminghttp://en.wikipedia.org/wiki/Radiation_patternhttp://en.wikipedia.org/wiki/Radiation_patternhttp://en.wikipedia.org/wiki/Finite_Impulse_Responsehttp://en.wikipedia.org/wiki/Minimum_mean_square_errorhttp://en.wikipedia.org/wiki/Steepest_descenthttp://en.wikipedia.org/wiki/Least_mean_squareshttp://en.wikipedia.org/w/index.php?title=Switched_beam&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Adaptive_array&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Adaptive_array&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Adaptive_array&action=edit&redlink=1http://en.wikipedia.org/wiki/Cell_phonehttp://en.wikipedia.org/wiki/Technologyhttp://en.wikipedia.org/wiki/Radio_communicationshttp://en.wikipedia.org/wiki/Software_defined_antennahttp://en.wikipedia.org/wiki/Software_defined_antennahttp://en.wikipedia.org/wiki/Cognitive_radiohttp://en.wikipedia.org/wiki/Receiver_(radio)http://en.wikipedia.org/wiki/Digital_signal_processorhttp://en.wikipedia.org/wiki/Transmitterhttp://en.wikipedia.org/wiki/Digital-to-analog_converterhttp://en.wikipedia.org/wiki/RADARhttp://en.wikipedia.org/wiki/Radio_astronomyhttp://en.wikipedia.org/wiki/Radio_telescopehttp://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/W-CDMAhttp://en.wikipedia.org/wiki/W-CDMAhttp://en.wikipedia.org/wiki/UMTShttp://en.wikipedia.org/wiki/Beamforminghttp://en.wikipedia.org/wiki/Multiple_signal_classificationhttp://en.wikipedia.org/wiki/Estimation_of_signal_parameters_via_rotational_invariance_techniqueshttp://en.wikipedia.org/wiki/Estimation_of_signal_parameters_via_rotational_invariance_techniqueshttp://en.wikipedia.org/w/index.php?title=Spatial_spectrum&action=edit&redlink=1http://en.wikipedia.org/wiki/Beamforminghttp://en.wikipedia.org/wiki/Radiation_patternhttp://en.wikipedia.org/wiki/Finite_Impulse_Responsehttp://en.wikipedia.org/wiki/Minimum_mean_square_errorhttp://en.wikipedia.org/wiki/Steepest_descenthttp://en.wikipedia.org/wiki/Least_mean_squareshttp://en.wikipedia.org/w/index.php?title=Switched_beam&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Adaptive_array&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Adaptive_array&action=edit&redlink=1


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direction of interest while simultaneously nulling interfering signals. Beam direction can beestimated using the so-called direction-of-arrival (DOA) estimation methods.

In 2008, the United StatesNTIAbegan a major effort to assist consumers in the purchaseofdigital television converter boxes. Through this effort, many people have been exposed tothe concept of smart antennas for the first time. In the context of consumer electronics, a

"smart antenna" is one that conforms to the EIA/CEA-909 Standard Interface.

Extension of smart antennas

Smart antenna systems are also a defining characteristic ofMIMO systems, such asthe IEEE802.11n standard. Conventionally, a smart antenna is a unit of a wirelesscommunication system and performs spatial signal processing with multiple antennas.Multiple antennas can be used at either the transmitter or receiver. Recently, the technologyhas been extended to use the multiple antennas at both the transmitter and receiver; such asystem is called a multiple-input multiple-output (MIMO) system. As extended SmartAntenna technology, MIMO supports spatial information processing, in the sense thatconventional research on Smart Antennas has focused on how to provide a beamformingadvantage by the use of spatial signal processing in wireless channels. Spatial informationprocessing includes spatial information coding such as spatial multiplexing and DiversityCoding, as well as beamforming.

8. Applications

At the present rates of 15-30 Mbit/s, 4G is capable of providing users with streaming highdefinition television. At rates of 100 Mbit/s, the content of a DVD-5 (for example a movie),can

be downloaded within about 5 minutes for offline access.

Next generation wireless technologies can serve in various aspects like:

Voice: Voice is and remains the most important type of application in mobiletelecommunications. However, it will increasingly be combined with other forms ofcommunication to form multimedia communication. Even the pure voice service can providenew possibilities for applications. It is already possible to set up multipoint conference calls,but this has not been widely exploited.

Messaging:The basic text-based SMS will also be available in 3G/4G, but the faster datarates of the new system make it possible to send much more than plain text in thesemessages. There is a new concept developed based on the notion of an enhanced SMSconcept. This is called the multimedia messaging service (MMS). An MMS message cancontain more than one component; these components are then combined in the user interfaceto produce a multimedia presentation. A simple MMS application could be an electronic picture postcard. Other MMS examples include electronic newspapers, news, trafficinformation, maps and driving instructions, music on demand, advertisements, and on-lineshopping.
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Internet access: Fortunately, this access will be relatively easy to implement in a 4Gterminal. The 3GPP is specifying an all-IP network, which means that Internet protocolscould be used all the way down to the terminal level. A mobile terminal would be an Internetnode, just like any PC, with its own IP address number

Location based applications: This includes emergency services, value added personal

services, commercial services, traffic and coverage measurement, location speed anddirection, security and privacy.

Games:Games will be another major application segment in 4G. Most people do not admitthat they like playing computer games, but despite this, the games are still selling extremelywell. So this would be another important application of next generation wireless system.

Electronic agents: Electronic agents are defined as mobile programs that go to places in thenetwork to carry out their owners instructions. Agents are self-contained programs thatroam communication networks, delivering and receiving messages or looking for informationor services. This is an efficient way to get things done on the move. Certainly, 4G terminalswill give their owners much more control over their lives than todays mobile phones. They

will be e-assistance, e-secretaries, e-advisors, e-administrators etc. This kind of control iswhat home automation applications anticipate.

Dating applications:Many people prefer to get to know other people without revealing theirown identity first. The technical implementation of a dating application may vary. It can be asimple bulletin board with dating adverts combined with an anonymous e-mail server, or itcould be a lonely-hearts mobile chat room. Users can also set up their own profiles (or theprofile for the company they seek), and wait until the matchmaker application finds a suitablevictim. Dating ads may also include still images and audio clips.

9. Conclusion

Nowadays, wireless technology is getting popular and important in the network and theInternet field. 4G just right started from 2002 and there are many standards and technologies,which are still in developing process. Therefore, no one can really sure what the future 4Gwill look like and what services it will offer to people. However, we can get the general ideaabout 4G from academic research; 4G is the evolution based on 3Gs limitation and it willfulfill the idea of WWWW, World Wide Wireless Web, offering more services and smoothglobal roaming with inexpensive cost.

10.Reference

http://www.fcc.gov/oet/cognitiveradio/.


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http://www.fcc.gov/oet/ea/presentations/files/may04/May_04_Software_defined&Cognitive_Radio-AL.pdf

http://en.wikipedia.org/

http://www.it.kth.se/~jmitola/Mitola_Dissertation8_Integrated.pdf

http://grouper.ieee.org/groups/emc/emc/1900/3/index.htm

Documents

Key Technologies for the Next Generation Wireless