Long Term Evolution ( LTE )

Long Term Evolution

LTE (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 telephone networks [2].

Mobile broadband will be the main focus in the next internet generation since it grows such a way that it can adapt broadband access in everywhere. Service providers will have a LTE network platform to deliver best mobile broadband services to the customer that can support the fast growth rate of subscriber including with high data rates [6]. LTE will not only make existing applications faster, but also enable those new applications which are previously available only on a wired internet connection [4]. LTE will also bring more improved business proposition compared to the related or similar previous technologies.

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Motivation for LTE:

Broadband subscriptions are expected to reach 3.4 billion by 2014[6]. About 80 percent of broadband subscribers will use mobile broadband (Figure 1) where fixed broadband subscribers are about near to 18 percent. The figure strongly supports that mobile broadband users will increase significantly in the next few years. Packet data traffic increased much more than voice traffic [10] since last 3 year (see Figure 2). Packet data traffic crossed voice traffic during May 2007, because of the introduction of HSPA [7] in the networks. In many cases, mobile broadband can compete with fixed broadband on price, performance, security and convenience. These all worked as a motivation for introduction of new technique which can satisfy this continuing high data rate user demand.

A number of broadband applications are significantly enhanced with mobility. Community sites, search engines, presence applications and content-sharing sites such as YouTube are a few examples. These applications become significantly more valuable to users including mobility. The high peak rates and short latency of LTE also enable real-time applications in mobile networks such as gaming and video-conferencing.

-->The motivation of LTE includes some basic criteria such as shifting UMTS towards packet only system, higher data rate, reduced control plane latency significantly, simplify architecture, and reduce number of network elements and high quality of service.

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Figure1: User Growth rate in Broadband service from 2007 – 2014 [6]

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Figure2: Data traffic Growth in WCDMA networks worldwide [6]

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LTE Evolution:

As LTE introduced for high data rates, it varies significantly with previous GSM technologies in terms of data rate. The data rate of LTE is 100 Mbps whereas HSDPA (3.5G) data rate is only 14.4 Mbps. The following figure -3 depicts the general evolution trend in GSM world considering the data rate. The evolution starts from 2G and ends at 4G with respective data rate.

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Figure-3: LTE Evolution [12]

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The technical idea about the evolution of LTE with the different forms of 3G architectures can be understand from the figure-4. Although LTE uses a different form of radio interface, using OFDMA / SC-FDMA instead of CDMA, there are many similarities with the earlier forms of 3G architecture.

LTE can be seen for provide a further evolution of functionality, increased speeds and general improved performance.

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Feature	WCDMA (UMTS)	HSPA HSDPA / HSUPA	HSPA+	LTE
Max downlink speed bps	384 k	14 M	28 M	100M
Max uplink speed bps	128 k	5.7 M	11 M	50 M
Latency round trip time approx	150 ms	100 ms	50ms (max)	~10 ms
3GPP releases	Rel 99/4	Rel 5 / 6	Rel 7	Rel 8
Approx years of initial roll out	2003 / 4	2005 / 6	HSDPA 2007 / 8 HSUPA 2008 / 9	2009 / 10
Access methodology	CDMA	CDMA	CDMA	OFDMA / SC-FDMA

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Table 1: LTE evolution with different 3G architecture [13]

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Main characteristics of LTE:

There are many characteristics of LTE are available. Some of the important and main characteristics are as follows [5]:

Data Rate: Peak data rates target 100 Mbps (downlink) and 50 Mbps (uplink) for 20 MHz spectrum allocation, assuming 2 receive antennas and 1 transmit antenna at the terminal.

Throughput: Target for downlink average user throughput per MHz is 3-4 times better than release 6. Target for uplink average user throughput per MHz is 2-3 times better than previous 3GPP release 6

Spectrum Efficiency: Downlink target is 3-4 times better than release 6. Uplink target is 2-3 times better than previous 3GPP release 6.

Latency: The one-way transit time between a packet being available at the IP layer in either the UE or radio access network and the availability of this packet at IP layer in the radio access network/UE shall be less than 5 ms.

Bandwidth: Scalable bandwidths of 5, 10, 15, 20 MHz shall be supported. Also bandwidths smaller than 5 MHz shall be supported for more flexibility, i.e. 1.4 MHz and 3 MHz.

Simple Architecture: A large amount of the work is aimed at simplifying the architecture of the system, as it transits from the existing UMTS circuit + packet switching combined network, to an all-IP flat architecture system

Common Platform: Through the LTE core network, mobile operators will be able to connect different access technologies to a single core network, allowing users, wherever they are, using any device, to access common operator provided applications and content through any access technology. This will allow the true realization of a converged multimedia personalized user experience

Interworking: Interworking with existing UTRAN/GERAN systems and non-3GPP systems shall be ensured. Multimode terminals shall support handover to and from UTRAN and GERAN as well as inter-RAT measurements. Interruption time for handover between E-UTRAN andUTRAN/GERAN shall be less than 300 ms for real time services and less than 500 ms for non-real time services.

Multimedia Broadcast Multicast Services (MBMS): MBMS shall be further enhanced and is then referred to as E-MBMS. Note: E-MBMS specification has been largely moved to 3GPP release 9.

Costs: Reduced CAPEX and OPEX including backhaul shall be achieved. Reasonable system and terminal complexity, cost and power consumption shall be ensured. All the interfaces specified shall be open for multi-vendor equipment interoperability.

Mobility: The system should be optimized for low mobile speed (0-15km/h), but higher mobile speeds shall be supported as well including high speed environment as special case.

Spectrum allocation: Operation in paired (Frequency Division Duplex / FDD mode) and unpaired spectrum (Time Division Duplex / TDD mode) is possible.

Co-existence: Co-existence in the same geographical area and colocation with GERAN/UTRAN shall be ensured. Also, co-existence between operators in adjacent bands as well as cross-border coexistence is a requirement.

Quality of Service: End-to-end Quality of Service (QoS) is supported. VoIP should be supported with at least as good radio and backhaul efficiency and latency as voice traffic over the UMTS circuit switched networks

Less Power Consumption: Allow for reasonable terminal power consumption. It is one of the important characteristics of LTE

Increased Service Provisioning: It is possible to provide more services at lower cost with better user experience using LTE

Architecture of LTE:

LTE introduces simple architecture in the cellular network. LTE is implemented including SAE which is known as System Architecture Evolution. System Architecture Evolution (SAE) is the core network architecture of 3GPP’s future LTE wireless communication standard.

SAE is the evolution of the GPRS core network, with some differences like simplified architecture, all IP Network (AIPN)[8], support for higher throughput and lower latency radio access networks (RANs), support for, and mobility between, multiple heterogeneous RANs, including legacy systems as GPRS, but also non-3GPP systems (WiMAX).

LTE enabled base station is called eNodeB. LTE is directly connected with SAE gateway, which is working as a core network element and reduces other intermediary node for better performance in service and cost efficiency in operation. Packet Data Serving Node (PDSN) of CDMA network, Service GPRS support node (SGSN) is packet serving node for both GSM and WCDMA, which are also connected to the SAE gateway. Control signaling, for example for mobility, is handled by the Mobility Management Entity (MME) node, separate from the gateway, facilitating optimized network deployments. Home Subscriber Server (HSS), which contain the subscriber profile, connects to MME through diameter protocol same as like as Policy and charging rules function (PCRF). This means all

Interfaces in the architecture are IP interfaces

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Figure 4: Flat Architecture of LTE [6]

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LTE Technology:

The pre-4G technology 3GPP Long Term Evolution (LTE) is often branded "4G", but the first LTE release does not fully comply with the IMT-Advanced requirements. LTE has a theoretical net bitrate capacity of up to 100 Mbit/s in the downlink and 50 Mbit/s in the uplink if a 20 MHz channel is used - and more if multiple-input multiple-output (MIMO), i.e. antenna arrays, are used. The physical radio interface was at an early stage named High Speed OFDM Packet Access (HSOPA), now named Evolved UMTS Terrestrial Radio Access (E-UTRA).

E-UTRAN Air Interface:

The proposed E-UTRAN system uses orthogonal frequency division multiplexing (OFDMA) for the downlink (tower to handset). OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for wide carriers with high peak rates. It is a well-established technology, for example in standards such as Institute of Electrical and Electronics Engineers (IEEE) 802.11a/b/g, 802.16.

OFDMA for Downlink:

OFDM uses a large number of narrowband sub-carriers or tones for multi-carrier transmission. The basic LTE downlink physical resource can be explained as a time-frequency grid, as illustrated in Figure 5. In the frequency domain, the spacing between the sub-carriers is 15 kHz. One resource element carries QPSK, 16QAM or 64QAM modulated bits. For example with 64QAM, each resource element carries six bits. The OFDM symbols are grouped into resource blocks. The resource blocks have a total size of 180 kHz in the frequency domain and 0.5ms in the time domain.

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Figure -5: The LTE downlink physical resource based on OFDM

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Each user is allocated a number of a resource blocks in the time–frequency grid. The more resource blocks a user receives and the higher the modulation used in the resource elements, the higher the bit-rate. The allocation of resource block for users depends on the advanced scheduling mechanisms in the frequency and time dimensions.

SC-FDMA for Uplink:

LTE uses Single Carrier FDMA (SC-FDMA) for the uplink .SC-FDMA overcomes the drawback of normal FDMA, which has the high Peak to Average Power Ratio (PAPR). High PAPR is expensive, inefficient power amplifier, increase the cost of terminal and drains the battery faster. LTE solves this problem by grouping the resource block in such a way that reduces the power consumption. A low PAPR also improves the coverage and cell edge performance.

Frequency bands for FDD & TDD

LTE can be used in both paired (FDD) and unpaired (TDD) spectrum. With Frequency Division Duplexing (FDD), downlink and uplink traffic is transmitted simultaneously in separate frequency bands. With TDD, the transmission in uplink and downlink is discontinuous within the same frequency band. Each mode has its own frame structure within LTE and these are aligned with each other meaning that similar hardware can be used in the base stations and terminals to allow for economy of scale.

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Figure -6: FDD & TDD in LTE

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Advanced antennas:

Advanced antenna solutions introduced in HSPA Evolution are also used by LTE. LTE employs MIMO (Multiple input multiple output) with up to four antennas per station. By using MIMO, these additional signal paths can be used to increase the throughput.

When using MIMO, it is necessary to use multiple antennas to enable the different paths to be distinguished. Accordingly schemes using 2 x 2, 4 x 2, or 4 x 4 antenna matrices can be used. Solutions

Incorporating multiple antennas meet next generation mobile broadband network requirements for high peak data rates, extended coverage and high capacity.

LTE Specification:

LTE specification is defined by 3rd Generation Partnership Project (3GPP) [9]. The specification includes major parameters and user equipment categories of LTE are given below: [all specifications are according to www.3gpp.org]

Access Scheme	UL	DFTS-OFDM
	DL	OFDMA
Bandwidth		1.4, 3, 5, 10, 15, 20 MHZ
Minimum TTI		1 msec
Sub-carrier spacing		15 KHz
Cyclic prefix length	Short	4.7 µsec
	Long	16.7 µsec
Modulation		QPSK, 16QAM, 64QAM
Spatial Multiplexing		Single layer for UL per UE Up to 4 layers for DL per UE MU-MIMO supported for UL and DL

Table-2: 3GPP LTE Release 8 Major Parameters

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Category		1	2	3		4		5
Peak rate Mbps	DL	10	50	100		150		300
	UL	5	25	50		50		75
Capability for Physical Functionalities
RF bandwidth		20 MHz
Modulation	DL	QPSK, 16QAM, 64QAM
	UL	QPSK, 16QAM		QPSK, 16QAM, 64QAM
Multi-antenna
2 Rx diversity		Assumed in performance requirements
2 X 2 MIMO		Not Supported			Mandatory
4 X 4 MIMO		Not Supported					Mandatory

Table -3: 3GPP LTE-Release 8 User Equipment Categories

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Technical Specification of LTE radio interfaces:

o LTE is based on Frequency Domain Multiplexing ( OFDM )

o For every 20 MHz of spectrum, peak download rates of 326.4 Mbit/s for 4x4 antennas, and 172.8 Mbit/s for 2x2 antennas. [2]

o Peak upload rates of 86.4 Mbit/s for every 20 MHz of spectrum using a single antenna[2]

o Increased spectrum flexibility, with supported spectrum slices as small as 1.5 MHz and as large as 20 MHz[3].

o A pre-coder is used to limit peak-to-average power ratios and thereby reduce terminal complexity.

o Based on channel quality modulation (up to 64 QAM) and channel coding rates are dynamically selected: FDD, TDD and half duplex FDD are supported.

o On the MAC layer, dynamic scheduling is done on a resource block pair basis, based on QoS parameters and channel quality.

o At least 200 active users in every 5 MHz cell. (Specifically, 200 active data clients)[2]

o Optimal cell size of 5 km, 30 km sizes with reasonable performance, and up to 100 km cell sizes supported with acceptable performance[2]

o Retransmissions are handled with two loops, a fast inner loop taking care of most errors complemented with a very robust outer loop for residual errors [1].

o Co-existence with legacy standards [ e.g. users can transparently start a call or transfer of data in an area using an LTE standard, and, should coverage be unavailable, continue the operation without any action on their part using GSM/GPRS or W-CDMA-based UMTS or even 3GPP2 networks such as CDMA2000]

o Support for MBSFN (Multicast Broadcast Single Frequency Network). This feature can deliver services such as Mobile TV using the LTE infrastructure, and is a competitor for DVB-H-based TV broadcast.

LTE advantages:

1. Flat architecture with few nodes and facilitates simple operation and maintenance.

2. Common Platform: LTE can be deployed in new and existing frequency bands. Through the LTE core network, mobile operators will be able to connect different access technologies like WCDMA, 2G, and 3G etc. to a single core network.

3. High Data Rate: Data rates 300 Mbps, delays 10 ms and spectrum efficiency gains over early 3G system releases.

4. High throughput, low latency, plugs and play.

5. Simultaneous user support: LTE provides the ability to perform two-dimensional resource scheduling (TDD and FDD), allowing support of multiple users in a time slot which is not possible in existing 3G technology because it performs one-dimensional scheduling. As a result, it limits service to one user for each timeslot. This capability of LTE results in a much better always-on experience.

6. An improved end-user experience and a simple architecture resulting in low operating costs.

7. Lower the costs of providing mobile broadband connectivity

8. Deliver new and improved services and applications.

9. LTE supports handover and roaming with the 3GGP mobile networks.

10. LTE needs lower power consumption. One of the reasons of this is the use of SC-FDMA modulation in uplink channels.

11. Security: LTE provides enhanced security through the implementation of UICC Subscriber Identity Module (SIM) [14]

12. Interworking: Interworking with existing UTRAN/GERAN (GSM/EDGE Radio Access Network) systems and non-3GPP systems is also a great advantage of LTE.

13. Real time Applications: LTE also enable real-time applications in mobile networks such as gaming and video-conferencing.

14. End-to-End Quality of Service (QoS) is ensured by LTE.

15. Scalable bandwidth is supported by LTE.

Comparison of LTE and Mobile WiMAX [11]:

Mobile WiMAX or 802.16e is a telecommunications technology that provides wireless transmission of data using a variety of transmission modes, from point-to-multipoint links to portable and fully mobile internet access. The technology provides up to 10 Mbps broadband speed without the need for cables. The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001.

WiMAX is already deployed by so many operators worldwide[15]. So LTE is considered as a very strong competitor of WiMAX in future. The following detail will try to find out the key parameter difference between the two technologies and also the strength and weakness of LTE and Mobile WiMAX.

Table - 1 presents the key comparison between LTE and mobile WiMAX. The comparisons mainly focus on the physical layer aspects of the radio network technology of two standards.

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Aspect	Mobile WiMAX	LTE
Access Technology	Downlink: OFDMA Uplink: OFDMA	Downlink: OFDMA Uplink: SC-FDMA
Frequency Band	2.3 – 2.4 GHz, 2.496 – 2.69 GHz 3.3 – 3.8 GHz	Existing and new Frequency Band (~ 2 GHz)
Bit-rate	Downlink: 75 Mbps ( MIMO 2 TX 2RX ) Uplink: 25 Mbps	Downlink: 100 Mbps ( MIMO 2 TX 2 RX ) Uplink: 50 Mbps
Channel Bandwidth	5, 8.75, 10 MHz	1.4 – 20 MHz
Latency	50 ms	10 ms
Cell Radius	2 – 7 Km	5 Km
Cell Capacity	100 - 200 user	More than 200 user at 5 Hz More than 400 user for larger BW
Mobility: Speed Handovers	up to 120 Km/H Optimized hard handover supported	Up to 250 Km/H Inter-cell soft handover supported.
Legacy	IEEE16.a through IEEE16.d	GSM/GPRS/EGPRS/UMTS/HSPA
Roaming Framework	New ( work in progress in WiMAX forum)	Auto through existing. GSM/ UMTS
Schedule Forecast: Standard Completed Initial Deployment Mass Market	2005 2007 – through 2007 2009	2007 2010 2012

Table -4: Comparison between Mobile WiMAX & LTE

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Comparative points between LTE and WiMAX to show advantage and disadvantage [16]:

1. Time advantage: WiMAX is already in the market while LTE is still in the lab or testing phase. So WiMAX has clearly time advantage over LTE.

2. Latency: LTE has less latency (10 ms) than WiMAX (50 ms) which has significant impact on real time applications. LTE has made possible to run the real time application in mobile broadband.

3. Easy upgrade and mobility: LTE is fully compatible with 3GPP standards. So LTE is working fine with all previous 3GPP architectures. LTE provides full mobility like WiMAX needs a mobile target with a speed lower than 120 km/h, LTE still operates with a target up to 350 km/h.

4. Handover Roaming: LTE supports handover and roaming with 3GPP mobile networks. This feature is not supported by WiMAX.

5. Power Consumption: LTE power consumption is significantly less than WiMAX because its uses SC-OFDMA modulation technique for uplink channel.

6. Infrastructure requirement: The initial costs of WiMAX are lower than LTE while the operators don’t have 2G – 3G network. WiMAX could be a good choice because the CAPEX of WiMax is lower than the CAPEX of LTE.

7. SIM Card: SIM card is mandatory for LTE. Without SIM card, user can’t have LTE service which is not as like as WiMAX. There is no such condition like SIM card in WiMAX.

8. WiMAX with Intel: WiMAX is already considered as an integrated feature with intel products which is obviously a great advantage of WiMAX against LTE.

9. Cell Capacity: The number of users can be supported by LTE cell is more than the WiMAX. Thus LTE cell capacity is much more than the mobile WiMAX.

LTE is considerd to be as a strong competitor of mobile WiMAX. LTE has lot of advantages against WiMAX to replace the technology. Though LTE is still in testing phase but LTE will take the leading position in future days. The challenge is to implement the LTE specification in real world environment.

LTE deployments and experience:

LTE specifications are almost done, now it’s time to implement the technology in the real world environment. The activities required to implement the technology and prepare it for commercial rollout, are prototyping, interoperability testing and field trials.

LSTI

A global group of vendors and operators have formed the LTE/SAE Trial Initiative (LSTI) to coordinate activities needed to take the technology from the standards to commercial rollout [18]. The initiative was formally launched in May 2007 by leading telecommunications companies like Alcatel-Lucent, Ericsson, Nokia, Nokia Siemens Networks, Nortel Nortel, Orange, T-Mobile, and Vodafone. [19] The LSTI is concerned with trials of the technology on actual implementations of the standard and it compares measurements from equipment in the lab and field against requirements and design targets from both 3GPP and The Next Generation Mobile Networks (NGMN) specification.

LSTI activity is divided into 5 sections, which are as follows:

1. Proof of Concert (POC)

2. Inter-operability Development Testing (IODT)

3. Interoperability Testing (IOT)

4. Friendly Customer Trials

5. PR/Marketing

A Proof of Concert (POC)

A proof of Concept activity combines the results of performing the LTE/SAE prototyping and field trial by different vendors to realize whether industry expectation on LTE can be achievable or not [17]. The activity was performed in early 2009. The measured result is presented in the figure-8, where the combine result of peak data rates of different LSTI vendors can be seen. From the figure it can be seen that 100 Mbps data rate is possible in uplink direction using 64 QAM technique which proves the specification of 3GPP standard. Results are plotted against “code rate,” which is the ratio of information bits to transmitted bits. Lower code rates are more robust to errors, but result in lower data rates.

The right hand picture of the figure-7, represents the spectral efficiency in LTE by different vendors. In order to prove that LTE will meet industrial expectations, a number of “proof points” were agreed between vendors and operators.

Figure -7: Peak data rates measured by different LSTI vendors.[17]

The proof points are as follows: [17]

• Peak data rates and spectral efficiencies meet targets of 100 Mb/s downlink (DL), 50 Mb/s uplink (UL)

• Expected data rates for end users

Impact of UE speeds up to 350 km/h

Sharing of resource between multiple users per cell

Benefits of frequency selective scheduling (FSS) and multi-user multiple-input

Multiple-output (MIMO) impact of protocol overheads to end application throughput

• Single and Multicell field testing.

• Voice over Internet Protocol (VoIP) and Quality of Service (QoS) support.

• Latency

–Air interface user-plane (U-plane) latency <>

–End-to-End U-plane latency <>

–Idle-active control-plane (C-plane) latency<>

Inter-operability Development Testing (IODT)

IODT is based on the cross vendor testing over the essential features of the air interface. The testing will includes the equipment compliant with the March 2009 version of the LTE/SAE standards. IODT will focus on the basic interoperability between handsets and infrastructure from one vendor partnership.

Interoperability Testing (IOT) will continue its testing from IODT with enhanced feature set. The testing includes S1 & X2 interface testing including with air interface from different vendors.

Friendly Customer Trials is the final stage in testing phase before the technology commercially launched. Friendly User will test the specified feature of LTE in pre-commercial environment. LTE is presently working on defining the test methods for this phase of LSTI activity.

Marketing is actually the last stage of LSTI activity to launch the product worldwide. After commercial launch, we also need to make sure that, it performs according to its standard.

The following figure-8 depicts the LSTI activity timeline:

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Figure-8: LSTI activity timeline [18]

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LSTI deployments

Most major mobile carriers in the United States and several worldwide carriers announced plans to convert their networks to LTE beginning in 2009. The world's first publicly available LTE-service was opened by TeliaSonera in the two Scandinavian capitals Stockholm and Oslo on the 14th of December 2009.

According to nokiasiemensnetworks.com, there are plenty of telecom carriers around the world that are going to LTE instead of WiMax. Some examples of this are:

· Biggest carriers in USA: AT&T, Verizon.

· Vodafone

· China Mobile

· DoCoMo (2010-2011).

· Others: KDDI, Telstra, Telecom Italia, China Telecom, Orange, and T-Mobile.

Future Challenge in LTE

LTE is considered as 3.9G which is obviously a strong step towards 4G. LTE will bring lot of changes in the mobile communication system. The future challenge of LTE is LTE-advanced. LTE advanced is considered as the 4G technology.

LTE Advanced is a suggestion for mobile communication standard, formally submitted as a candidate 4G systems to International Telecommunications Union Terrestrial (ITU-T) in the fall 2009, and expected to be released in 2011. It is standardized by the 3rd Generation Partnership Project (3GPP) as a major enhancement of the pre-4G 3GPP Long Term Evolution (LTE) standard. The major differences in LTE and LTE-advanced will be as like as table-5:

Feature	LTE	LTE -Advanced
Max downlink speed bps	100M	1G```
Max uplink speed bps	50 M	500 M
Latency (round trip time approx.)	~10 ms	Less than 5 ms
3GPP releases	Rel 8	Rel 10
Approx years of initial roll out	2009 / 10
Access methodology	OFDMA / SC-FDMA	OFDMA / SC-FDMA

Table-5: Feature of LTE and LTE-advanced [13]

LTE does not meet the IMT-advanced requirements for 4G also called IMT Advanced as defined by the International Telecommunication Union such as peak data rates up to 1 Gbits/s. International Mobile Telecommunications - Advanced (IMT-Advanced) is a concept from the ITU for mobile communication systems with capabilities which go further than that of IMT-2000. The future challenge of LTE will be the implementation of following feature of LTE-advanced. The feature for LTE advance will be as follows [13]:

1. Peak data rates: downlink - 1 Gbps; uplink - 500 Mbps.

2. Spectrum efficiency: 3 times greater than LTE.

3. Peak spectrum efficiency: downlink - 30 bps/Hz; uplink - 15 bps/Hz.

4. Spectrum use: the ability to support scalable bandwidth use and spectrum aggregation where non-contiguous spectrum needs to be used.

5. Latency: from Idle to Connected in less than 50 ms and then shorter than 5 ms one way for individual packet transmission.

6. Cell edge user throughput to be twice that of LTE.

7. Average user throughput to be 3 times that of LTE.

8. Mobility: Same as that in LTE

9. Compatibility: LTE Advanced shall be capable of interworking with LTE and 3GPP legacy systems.

Conclusion:

There is no doubt in the point that LTE is going to take the lead in the mobile communication system. LTE is not only providing the faster communication system but also making a lot of significant step towards GSM evolution. Mobile communication is shifting towards from voice traffic to data traffic. The transformation also includes circuit switching to packet switching. LTE is the perfect candidate to adopt these technological changes and take the communication technology farther beyond our imagination.

Glossary

DL Downlink

DVB Digital Video Broadcast

EDGE Enhanced Data for Global Evolution

FDD Frequency division duplex/duplexing

3GPP 3^rd Generation Partnership Project

GSM Global System for Mobile Communication

GPRS General Packet Radio Service

HSDPA High Speed Downlink packet Access

HSPA High Speed Packet Access

HSS Home Subscriber Server

IEEE Institute of Electrical and Electronics Engineers

LTE Long Term Evolution

MBMS Multimedia Broadcast Multicast Service

MIMO Multiple input, multiple output

MME Mobility Management Entity

NGMN Next generation mobile networks

OFDM Orthogonal frequency division multiplexing

PAPR Peak-to-average power ratio

PCRF Policy and Charging Rules Function

PDSN Pack Data Serving Node

QoS Quality of service

RAN Radio access network

SAE System Architecture Evolution

SC-FDMA Single Carrier Frequency Division Multiple Access

SGSN Serving GPRS Support Node

TDD Time division duplex/duplexing

UTRA Universal Terrestrial Radio Access

UE User Equipment

UL Uplink

UTRAN Universal Terrestrial Radio Access Network

UMTS Universal Mobile Telecommunication System

WCDMA Wideband Code Division Multiple Access

WiMAX Worldwide Interoperability for Microwave Access

Reference:

1. Andres Furuskar, Tomas Jonsson and Magnus Lundevall – “The LTE Radio Interface – Key Characteristics and Performance” – Ericsson Research, Sweden.

2. Wikipedia – [ www.wikepedia.com ]

3. Nomor Research Newsletter: LTE Physical Layer Signals and Channels-[ http://www.nomor-research.com/home/technology/3gpp-newsletter/-2007-08--lte-phy---signals-and-channels]

4. Experience LTE by Motorolla – [http://business.motorola.com/experiencelte/home.html]

5. 1MA111: UMTS Long Term Evolution (LTE) Technology Introduction- [http://www2.rohde-schwarz.com]

6. LTE-an Introduction- Ericsson [ www.ericsson.com]

7. EDGE, HSPA and LTE- The Mobile Broadband Advantage – Pysavy Research

8. 3GPP Long-Term Evolution Overview/ System Architecture Evolution-Ulrich Barth, September 2006, Alcatel-Lucent Ltd.

9. LTE, The Mobile Broadband Standard, 3GPP [http://www.3gpp.org/article/lte]

10. Verizon Wireless Global LTE Deployment Plans [http://news.vzw.com/LTE/]

11. A comparison of two Fourth Generation Technologies- WiMax and LTE –Jacob Scheim, December 2006, Communication and Signal Processing Ltd.[http://www.comsysmobile.com]

12. LTE Evolution [telecominfo.wordpress.com].

13. 3GPP Long Term Evolution & LTE-advanced[www.radio-electronics.com]

14. Benefits of LTE [www.lte.vzw.com]

15. WiMAX Mobile or 802.16e [www.wimax.com]

16. Comparison of LTE and Mobile WiMAX [www.4gwirelessjobs.com]

17. The LTE/SAE Trial Initiative: Taking LTE/SAE from Specification to Rollout – Julius Robson, Nortel and LSTI, LTE Part II, Release 8.

18. The LTE/SAE Trial Initiative; [ www.lstiforum.com ]

19. LSTI, “Latest Results from the LSTI,” Feb. 2009

[http://www.lstiforum.com/file/news/Latest_LSTI_Results_Feb09_v1.pdf]