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White PaperDecember 2008
Mobile LTE Network design with ICS telecom
Software solutions in radiocommunications
Abstract
Currently, UMTS networks worldwide are being upgraded to High Speed Downlink Packet Access (HSDPA) in order to increase data rate and capacity for downlink packet data. In the next step, High Speed Uplink Packet Access (HSUPA) will boost uplink performance in UMTS networks. However, in order to ensure the competitiveness of UMTS for the next 10 years and beyond, concepts for UMTS Long Term Evolution (LTE) have been investigated. The objective is a high-data-rate, low-latency and packet optimized radio access technology. This white paper describes the main features of the LTE concept and how these features can easily be handled by ICS telecom. Today, the ICS telecom software is able to provide a full solution for the LTE network design as well as for the coverage simulations, interference and traffic analysis and regarding the MBMS (Multimedia Broadcast Multicast Services) network management.
References
3GPP TR 25.913 ‘Feasibility Study of Evolved UTRA and UTRAN’ 3GPP TS 25.104 ‘Base Station (BS) radio transmission and reception (FDD)’ 3GPP TS 25.105 ‘Base Station (BS) radio transmission and reception (TDD)’
overview
2
Table of Content
1 Acronyms ___________________________________________________________________ 4
2 General considerations ________________________________________________________ 6
2.1 LTE standardization______________________________________________________ 6
2.2 LTE targets _____________________________________________________________ 7
2.3 What are the changes with UMTS technology?________________________________ 7
3 OFDMA downlink ____________________________________________________________ 8
3.1 OFDMA concept _________________________________________________________ 8
3.2 OFDMA structure with LTE (DL) __________________________________________ 93.2.1 Guard interval scheme ___________________________________________________ 93.2.2 Bandwidth and duplexing scheme (TDD or FDD) with LTE_____________________ 103.2.3 Time slot and frame structure _____________________________________________ 12
3.3 Generic frame structure (for TDD and TDD) ________________________________ 133.3.1 Presentation___________________________________________________________ 133.3.2 Cyclic prefix and reference symbol ________________________________________ 163.3.3 Alternative frame structure for TDD _______________________________________ 18
3.3.3.1 Tuning for alternative frame (14 slots of 0.675ms) ________________________ 183.3.3.2 Tuning for alternative frame (20 slots of 0.5ms) __________________________ 20
4 SC FDMA (UPLINK) ________________________________________________________ 21
5 LTE antenna system__________________________________________________________ 23
6 Traffic requirement for LTE ___________________________________________________ 24
7 Network design and analysis of LTE network with ICS telecom_______________________ 27
8 MBMS (Multimedia Broadcast Multicast Services)_________________________________ 29
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MOBILE LTE NETWORK DESIGNWITH ICS TELECOM
Note: all provided values are FOR IN FORMATION ONLY
1 Acronyms
ACPR Adjacent Channel Power Ratio
AASAdaptive Antenna System also Advanced Antenna
System
AMC Adaptive Modulation and Coding
BE Best Effort
BER Bit Error Ratio
BLER Block Error Ratio
BS Base Station
BS Base Station
CCI Co-Channel Interference
CINR Carrier to Interference + Noise Ratio
CP Cyclic Prefix
CPICH Common Pilot Channel
DL Downlink (forward link)
DPCH Dedicated Physical Channel
EIRP Effective Isotropic Radiated Power
eNB E-UTRAN NodeB
ErtPS Extended Non-Real-Time Packet Service
FBSS Fast Base Station Switch
FDD Frequency Division Duplex
FDD Frequency Division Duplex
FFRS Fractionnal frequency reuse scheme
FFT Fast Fourier Transform
FRS Frequency reuse scheme
FTP File Transfer Protocol
FUSC Fully Used Sub-Channel
HHO Hard Hand-Off
HiperMAN High Performance Metropolitan Area Network
HO Hand-Off
IEEE Institute of Electrical and Electronics Engineers
ISI Inter-Symbol Interference
LOS Line of Sight
MAC Media Access Control
MAN Metropolitan Area Network
MBMS Multimedia Broadcast Multicast services
MBS Multicast and Broadcast Service
MDHO Macro Diversity Hand Over
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MIMO Adaptive Multiple Input Multiple Output
MU Mobile Unit
NLOS Non Line-of-Sight
nrtPS Non-Real-Time Packet Service
OFDM Orthogonal Frequency Division Multiplex
OFDMA Orthogonal Frequency Division Multiple Access
P-CCPCH Primary Common Control Physical Channel
PICH Paging Indicator Channel
PUSC Partially Used Sub-Channel
QAM Quadrature Amplitude Modulation
QPSK Quadrature Phase Shift Keying
RSCP Received Signal Code Power
RSRP Reference Signal Received Power
RTG Receive/transmit Transition Gap
rtPS Real-Time Packet Service
SF Service Flow
SFN Single Frequency Network
SISO Single Input Single Output (Antenna)
SNIR Signal to Noise + Interference Ratio
SNR Signal to Noise RatioS-OFDMA Scalable Orthogonal Frequency Division Multiple Access
STC Space Time Coding
TDD Time Division Duplex
TDD Time Division Duplex
TTG Transmit/receive Transition Gap
UGS Unsolicited Grant Service
UL Uplink (reverse link)
UTRA UMTS Terrestrial Radio Access
UTRAN Universal Terrestrial Radio Access Network
VoIP Voice over Internet Protocol
WiMAX Worldwide Interoperability for Microwave Access
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2 General considerations
2.1 LTE standardization Following the Toronto workshop, in December 2004, 3GPP launched a feasibility study in order “to develop a framework for the evolution of the 3GPP Radio Access technology towards a high-data-rate, low-latency and packet-optimized radio-access technology”. In other words, the study would map out specifications for a radio access network (RAN) capable of supporting the broadband Internet user experience we already enjoy in today’s fixed networks – with the addition of full mobility to enable exciting new service possibilities.
Today, specifications for LTE are encapsulated in 3GPP Release 8, the newest set of standards that defines the technical evolution of 3GPP mobile network systems. Release 8 succeeds the previous iteration of 3G standards – Release 7 – that includes specifications for HSPA+, the ‘missing link’ between HSPA and LTE. Defined in 3GPP Releases 7 and 8, HSPA+ allows the introduction of a simpler, ‘flat’, IP-oriented network architecture while bypassing many of the legacy equipment requirements of UMTS/HSPA.
Fig1: Standardization timeline for 3GPP Long Term Evolution
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Fig2: 3GPP standards
2.2 LTE targets
The most important targets for the LTE technology are the following:
Provide up to 100 Mbps in downlink and 50 Mbps in uplink. 3 to 4 time the Rel6 in DL and 2 to 3 time in UL.
Reduce the latency (10ms). Increase the spectrum efficiency.
3 to 4 time the Rel.6 en DL, 2 to 3 time en UL. Modulation of the bandwidth.
1.25 / 2.5 / 5 / 10 / 15 / 20 MHz Support for inter working with existing 3G system (3GPP releases) and non-3GPP specified systems.
2G/3G/ Wlan / WiMAX PS domain for all the services (IP optimized).
Voice, data, HD video… Wide range of terminals
Mobile phones, computer, electronic devices, notebooks, gaming devices… Suppress of the dedicated channels
2.3 What are the changes with UMTS technology?
The most important targets for the LTE technology are the following:
New transmission radio technology. OFDMA in downlink, SC-FDMA in uplink and MIMO technology New network architecture (base station with more functionalities “eNodeB”, new core network
“Evolved Packet Core”).Existing GSM and WCDMA/HSPA systems are integrated to the evolved system
New physical layers.
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Fig3: Architecture of LTE and SAE (System Architecture Evolution)
3 OFDMA downlink
The technique of Orthogonal Frequency Division Multiplexing (OFDM) is based on the well-known technique of Frequency Division Multiplexing (FDM). In FDM different streams of information are mapped onto separate parallel frequency channels. Each FDM channel is separated from the others by a frequency guard band to reduce interference between adjacent channels.
3.1 OFDMA concept
LTE uses OFDM for the downlink (that is, from the base station to the terminal). OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for very wide carriers with high peak rates. It is a well-established technology, for example in standards such as IEEE 802.11a/b/g, 802.16, HIPERLAN-2, DVB and DAB. The advantages of the OFDMA technology are the following:
Reliability confirmed with the Wifi and WiMAX technology. High spectrum efficiency Flexibility in term of Time/Frequency allocation Compatibility with MIMO antennas.
The OFDM technique differs from traditional FDM in the following interrelated ways:
1. Multiple carriers (called sub-carriers) carry the information stream,
2. the sub-carriers are orthogonal to each other, and a guard time may be added to each symbol to combatthe channel delay spread.
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These concepts are illustrated in below figure:
…
Sub-carriersFFT
Time
Symbols
5 MHz Bandwidth
Guard Intervals
…
Frequency
Fig4: Frequency time representation of an OFDMA signal
In this figure, a signal with 5 MHz bandwidth is shown, but the principle is of course the same for the other E-UTRA bandwidths. Data symbols are independently modulated and transmitted over a high number of closely spaced orthogonal sub-carriers. In E-UTRA, downlink modulation schemes QPSK, 16QAM, and 64QAM are available.
In practice, the OFDM signal can be generated using IFFT (Inverse Fast Fourier Transform) digital signal processing. The IFFT converts a number N of complex data symbols used as frequency domain bins into the time domain signal.
3.2 OFDMA structure with LTE (DL)In contrast to an OFDM transmission scheme, OFDMA allows the access of multiple users on the available bandwidth. Each user is assigned a specific time-frequency resource. As a fundamental principle of E-UTRA,the data channels are shared channels, i.e. for each transmission time interval of 1 ms, a new scheduling decision is taken regarding which users are assigned to which time/frequency resources during this transmission time interval.
3.2.1 Guard interval scheme
A guard interval may be added prior to each useful OFDM symbol. This guard time is introduced to minimize the inter-OFDM-symbol-interference power caused by time-dispersive channels. The guard interval duration Tg (which corresponds to Np prefix samples) must hence be sufficient to cover the most of the delay-spread energy of a radio channel impulse response. In addition, such a guard time interval can be used to allow soft-handover.
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ICS telecom supports all the OFDMA technology (LTE, IEEE 802.11/802.16…) and allows to take in charge all
the available configurations for the using of the LTE technology.
Parameters windows for the OFDMA system with ICS telecom
ICS telecom’s OFDM parameters box for simulating multipath reflection can highlight the cases where the
signal is damaged due to the reflected signal being greater (by a user-defined margin in dB) than the direct
path threshold and with a ToA outside of the OFDM receiver Guard interval:
Constructive and Destructive OFDM signals in ICS telecom
3.2.2 Bandwidth and duplexing scheme (TDD or FDD) with LTE
LTE leverages new and wider spectrum, up to 20 MHz, to provide a capacity boost in high-demand areas, and complements the existing HSPA and HSPA+ deployments. OFDMA technology provides increasingly higher capacity for wider bandwidths—making LTE best suited for bandwidths of 10 to 20 MHz.
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At the same time, LTE is flexible enough to be deployed in any bandwidth combination, which makes it suitable for spectrum resources of various sizes. LTE deployments in smaller bandwidths have lower spectral efficiency due to the relatively higher overheads for control and signaling. In a typical 5 MHz system deployment, HSPA+ and LTE provide similar data capacity and end-user experience.
BW 1.25 MHz FDD 5 MHZ FDD 10MHz 20MHz FDDDownlink (DL)(4X4 MIMO) 16 68 138 277
Uplink (UL) 4 18 37 75Fig5: LTE DL and UL pick data rate (Mbps)
LTE supports both FDD and TDD modes, allowing operators to address all available spectrum resources. Multiple users can be multiplexed, both in time and in frequency, with pilot and signalling information. In the
frequency dimension, users data symbol can be multiplexed on different numbers of useful sub-carriers. In
addition, sub-carriers or group of sub-carriers can be reserved to transmit pilot, signalling or other kind of
symbols (Paragraph 2.4). Multiplexing can also be performed in the time dimension, as long as it occurs at the
OFDM symbol rate or at a multiple of the symbol rate (from one IFFT computation to the other, every k*Ts
seconds). The modulation scheme (modulation level) used for each sub-carrier (between 72 and 2048 sub
carriers for OFDMA system) can also be changed at the corresponding rate, keeping the computational
simplicity of the FFT-based implementation. This allows 2-dimensional time-frequency multiplexing, of the
form shown in bellow figure.
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ICS telecom deals with all the OFDMA bandwidth (1.25MHz, 5MHz, 10MHz…) and allow to take in charge all
the configurations for the LTE technology:
The choice of the duplex mode used by the LTE base stations can be done in their technical parameters:
3.2.3 Time slot and frame structure
With LTE technology (base on the OFDMA for the DL transmission), one resource element carries QPSK, 16QAM or 64QAM. 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. Each 1ms Transmission Time Interval (TTI) consists of two slots (Tslot) also called sub frame. Each user is allocated a number of resource blocks in the time–frequency grid. The more resource blocks a user gets, and the higher the modulation used in the resource elements, the higher the bit-rate. Which resource blocks and how many the user gets at a given point in time depend on advanced scheduling mechanisms in the frequency and time dimensions. The scheduling mechanisms in LTE are similar to those used in HSPA, and enable optimal performance for different services in different radio environments.
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Fig6: Description of the resource block according to the time slots
LTE proposes two kind of frame structure: Generic frame structure (for TDD and FDD mode) and alternative frame structure (only for TDD mode). The two structures are described on the newt chapter.
3.3 Generic frame structure (for TDD and TDD)
3.3.1 Presentation
The generic frame structure is used for the FDD and TDD modes. The generic frame structure is composed as follows:
10 ms radio frame is divided into 20 equally sized slots of 0.5 ms. A sub-frame consists of two consecutive slots, so one radio frame contains 10 sub-frames. This is
illustrated in the bellow figure (Ts is expressing the basic time unit corresponding to 30.72 MHz).
A prefix is generated using the last block of Np samples from the useful OFDM symbol. Note that since the prefix is a cyclic extension to the OFDM symbol, it is often termed Cyclic Prefix (CP). Similarly, a cyclic postfix could be appended to the OFDM symbol. One downlink slot consists of DL Nsymb OFDM symbols. To each symbol, a cyclic prefix (CP) is appended as guard time. DL Nsymb depends on the cyclic prefix length. The generic frame structure with normal cyclic
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prefix length contains DL Nsymb = 7 symbols (Fig7). This translates into a cyclic prefix length of TCP _5.2μs for the first symbol and TCP _4.7μs for the remaining 6 symbols. Additionally, an extended cyclic prefix is defined in order to cover large cell scenarios with higher delay spread and MBMS transmission (SFN broadcast system). The generic frame structure with extended cyclic prefix of TCP-E _16.7μs contains DL Nsymb = 6 OFDM symbols (sub-carrier spacing 15 kHz). The generic frame structure with extended cyclic prefix of TCP-E _33.3μs contains DLNsymb = 3 symbols (sub-carrier spacing 7.5 kHz).
The cyclic prefix should absorb most of the signal energy dispersed by the multi-path channel. The entire the inter-OFDM-symbol-interference energy is contained within the prefix if the prefix length is greater than that of the channel total delay spread.
In general, it is sufficient to have most of the energy spread absorbed by the guard interval, given the inherent robustness of large OFDM symbols to time dispersion, as detailed in the next section.
After the insertion of the guard interval the OFDM symbol duration becomes The OFDM sampling frequency Fo can therefore be expressed as
s
p
o T
NNF
.
Hence, the sub-carrier separation becomes:
N
Ff o .
It is also worth noting that time-windowing and/or filtering is necessary to reduce the transmitted out-of-band power produced by the ramp-down and ramp-up at the OFDM symbol boundaries in order to meet the spectral mask.
As shown bellow, the OFDM symbol number Nsymb (by slot) depends on the cyclic prefix size:
Configuration NsymbGeneric structure
Alternative Structure
Normal Cyclic prefix (CP)
(Delta F= 15Khz) 7 9
Extended Cyclic prefix (CP)
(Delta F= 15Khz) 6 8
(Delta F= 15Khz) 3 4Source: 3GPP
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Below is described an E-UTRA Generic frame structure (available for FDD and TDD):
Legend: Transmitted signal in each slot is described by a resource grid of sub-carriers and available OFDM symbols. Each element in the resource grid is called a resource element and each resource element corresponds to one complex-valued modulation symbol. The number of OFDM symbols per sub-frame is 7 for normal cyclic prefix and 6 for extended cyclic prefix. In both downlink and uplink, a basic scheduling unit is denoted a resource block. A resource block is defined as 7 or 6 consecutive OFDM symbols in the time domain depending on the cyclic prefix length and 12 consecutive sub-carriers (180 kHz) in the frequency domain.
Using the new OFDMA calculator of ICS telecom, the user can define:
The number of symbols in the OFDMA frame
The number of overhead symbols in the Downlink
The number of overhead symbols in the Uplink
The UL/DL duration ratio
The number of symbols included in the Time Transition Gap (TTG)
Based upon these inputs, the software calculates the number of data symbols used in DL and UL. If crossed with the modulation and the number of OFDMA data sub-carriers used per frame, ICS telecom can automatically calculate the corresponding throughput in DL and UL.
1. Each resource element indentified by his own frequency indices k and temporal l,
2. One resource block is defined by a consecutive OFDM symbol (called “Nsymb”) in the time and by NBW=12 consecutive sub carriers.
3. Each OFDM symbol use 12 sub carriers during a duration equal to Ts/Nsymb.
4. Each OFDM signal is supported by at least 72 sub carriers (until 2048).
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OFDMA calculator in ICS telecom: Calculation of the available sub carriers and number data symbol per OFDMA trame
3.3.2 Cyclic prefix and reference symbol
Bellow an example of long and short prefix (CP) according to the time slot structure:
Short CP:
S1 S2 S3 S4 S5 S6 S7
0.5ms Long CP:
S1 S2 S3 S4 S5 S6 S7
0.5ms
OFDM symbol (TS=66.57µs)
Cyclic prefix (long CP= 16.7µs; short CP=5.21 µs for the first one and 4.69 µs for the next).
Some symbols are used for: The measurement of the DL channel. To take in charge the coherency in term of detection/Demodulation of the receiver. Synchronization signals: Cell search and initial acquisition.
E-UTRA uses a hierarchical cell search scheme similar to WCDMA. This means that the synchronization acquisition and the cell group identifier are obtained from different SCH signals.A primary synchronization signal (P-SCH) and a secondary synchronization signal (S-SCH) are defined with a pre-defined structure. They are transmitted on the 72 centre sub-carriers (around DC sub-carrier) within the same predefined slots (twice per 10 ms) on different resource elements.
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As additional help during cell search, a Common Control Physical Channel (CCPCH) is available which carries BCH type of information, e.g. system bandwidth. It is transmitted at pre-defined time instants on the 72 sub carriers centered around DC sub-carrier.
Fig7: P-SCH and S-SCH structure
In order to reduce complexity of the LTE protocol architecture, the number of transport channels was reduced. This is mainly due to the focus on shared channel operation, i.e. no dedicated channels are used any more.
Transport channelsDownlink transport channels are:
Broadcast Channel (BCH) Downlink Shared Channel (DL-SCH) Paging Channel (PCH) Multicast Channel (MCH)
Uplink transport channels are: Uplink Shared Channel (UL-SCH) Random Access Channel (RACH)
Logical channelsLogical channels can be classified in control and traffic channels.
Control channels are: Broadcast Control Channel (BCCH) Paging Control Channel (PCCH) Common Control Channel (CCCH) Multicast Control Channel (MCCH) Dedicated Control Channel (DCCH)
Traffic channels are:
Dedicated Traffic Channel (DTCH)
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Fig8: Description of transport channels with LTE
3.3.3 Alternative frame structure for TDD
The alternative frame structures have been developed for the TDD mode (only). Two kind of alternative frames are available for LTE technology:
3.3.3.1 Tuning for alternative frame (14 slots of 0.675ms)
Transmissionbandwidth
1.25MHz 2.5MHz 5MHz 10MHz 15MHz 20MHz
Sub frame duration
0.675ms
Sub carriers spacing
15khz
Frequency Sampling
1.92MHz (1/2*3.84MHz)
3.84MHz 7.68MHz(2*3.84MHz)
15.36 MHz(4*3.84MHz)
23.04 MHz(6*3.84MHz)
30.72 MHz(8*3.84MHz)
FFT size 128 256 512 1024 1536 2048
Number of sub carriers 76 151 301 601 901 1201
Nb of OFDM symbol per sub frame
9/8
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(Long/Short CP)
CP size (µs/sample)
Short 7.29/14 7.29/28 7.29/56 7.29/112 7.29/168 7.29/224
Long 16.67/32 16.67/64 16.67/128 16.67/256 16.67/384 16.67/512
TS Interval (sample)
Short 18 36 72 144 216 288
Long 16 32 64 128 192 256Source: 3GPP TR 25.814
Additional remarks:1. The duration of one sub-frame (2 slots) correspond to the minimum TTI in DL that is 1ms.
2. It may be possible to merge several sub-frames into one TTI longer in order to optimize the QOS. In this case, the TTI transmitted by the node B (via the modulation, type of codage and the bloc size) may be a dynamic “parameter” of the channel.
3. A longer CP may be implemented for the broadcast multi cell or for the big cells in order to reduce the more important delays due to the multipath reflections.
All those parameters are take in charge by ICS telecom via the function “OFDMA calculator” as shown in the bellow table:
Parameters in ICS telecom Transmission bandwidth Configurable
Sub frame duration Automatically calculatedSub carriers spacing Automatically calculatedFrequency Sampling Automatically calculated
FFT size Automatically displayedNumber of sub carriers Configurable
Nb of OFDM symbol per sub frame (Long/Short CP) Configurable
CP size (µs/sample) Automatically calculated
Tab1: Frame tuning configuration with ICS telecom
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3.3.3.2 Tuning for alternative frame (20 slots of 0.5ms)
Transmission Bandwidth
1.25MHz 2.5MHz 5MHz 10MHz 15MHz 20MHz
Sub frame duration
0.675ms
Sub carriers spacing
15khz
Frequency Sampling
1.92MHz (1/2*3.84MHz)
3.84MHz 7.68MHz(2*3.84MHz)
15.36 MHz(4*3.84MHz)
23.04 MHz(6*3.84MHz)
30.72 MHz(8*3.84MHz)
FFT size 128 256 512 1024 1536 2048
Number of sub carriers 76 151 301 601 901 1201
Nb of OFDM symbol per sub frame
(Long/Short CP)
7/6
CP size (µs/sample)
Short (4.69/9) X 6 (4.69/18) X 6 (4.69/36) X 6 (4.69/72) X 6 (4.69/108) X 6 (4.69/144) X 6
Long 16.67/32 16.67/64 16.67/128 16.67/256 16.67/384 16.67/512Source: 3GPP TR 25.814
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4 SC FDMA (UPLINK)
OFDMA (essentially the same overall complexity). Is currently adopted for uplink multiple access schemes for 3GPP LTE.In the uplink, Single-Carrier Frequency Division Multiple Access (SC-FDMA) is selected to efficiently meet E-UTRA performance requirements. SC-FDMA has many similarities to OFDM, chief among them for the uplink that frequency domain orthogonalilty is maintained among intra-cell users to manage the amount of interference generated at the base. SC-FDMA also has a low power amplifier de-rating (Cubic Metric / PAPR) requirement, thereby conserving battery life or extending range.
The baseline SC-FDMA signal is DFT-Spread OFDM (DFTSOFDM).The only difference from OFDM is the addition of the M-point FFT (DFT) in the figure which “spreads” M symbols onto the M sub-carriers selected by the symbol to sub-carrier mapping. The selected sub-carriers must also be either adjacent to or evenly spaced to maintain the low PA power de-rating. The signal is considered single carrier as the first M-point FFT and the larger N-point IFFT cancel each other resulting in a single carrier signal in the time domain. The receiver can use simple frequency domain equalization.
Fig 10: DFT spread with SC-FDMA technology
The advantages and the disadvantage of the SC-FDMA compare to the OFDMA system are summarized bellow:
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Advantage for SC-FDMA technique
The numerology can match the OFDM downlink, with excellent spectral occupancy due to the IFFT providing pulse shaping of the signal. The OFDM numerology provides for an additional vacant DC sub-carrier to simplify some receiver architectures; a vacant sub-carrier cannot be used with DFT-SOFDM without affecting the low PA de-rating property of DFT-SOFDM.
Two types of sub carrier mapping, distributed and localized, give system design flexibility to accommodate either frequency diversity or frequency selective gain.
Low PAPR Less sensitivity carrier
Better PAPR (Peak-to-Average Power Ratio) propertiescompared to an OFDMA system
The PAPR characteristics are important for cost-effective design of UE power amplifiers. Still, SC-FDMA signal processing has some similarities with OFDMA signal processing, so parametrization of downlink and uplink can be harmonized.
The main disadvantage of multi carrier modulation is that it exhibs a high peak-to-average ration (PAPR). Namely, the peak values of some of the transmitted signal could be much larger than the typical values.This could lead to a necessity of using circuits with linear characteristics within a large dynamic range; otherwise the signal clipping at high levels would yield a distortion of the transmitted signal out-of-band radiation.
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5 LTE antenna system
LTE uses advanced antenna techniques and wider spectrum allocations to provide higher data rates throughout the cell area. LTE supports MIMO, SDMA and beamforming. These techniques are complementary and can be used to trade off between higher sector capacity, higher user data rates, or higher cell-edge rates, and thus enable operators to have finer control over the end-user experience.
Downlink MIMO
LTE supports up to 4x4 MIMO in the DL (2x2 configuration for MIMO is assumed as baseline configuration), which uses four transmit antennas at the Node B to transmit orthogonal (parallel) data streams to the four receive antennas at the user equipment (UE). Using additional antennas and signal processing at the receiver and transmitter, MIMO increases the system capacity and user data rates without using additional transmit power or bandwidth. To be most effective, MIMO needs a high signal-to-noise ratio (SNR) at the UE and a rich scattering environment. High SNR ensures that the UE is able to decode the incoming signal, and a rich scattering environment ensures the orthogonality of the multiple data streams. The MIMO benefit is therefore maximized in a dense urban environment, where there is enough scattering and the small cell sizes provide an environment of high SNRs at the UE
Beamforming
Beamforming increases the user data rates by focusing the transmit power in the direction of the user, effectively increasing the received signal strength at the UE. Beamforming provides the most benefits to users in weaker-signal-strength areas, like the edge of the cell coverage. Beamforming ensures that cell-edge rates are high, and enables the operator to deploy high-bandwidth services without concern for service degradation at the cell edge.
ICS telecom allows to take into account those kinds of antennas
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Adaptive antenna systems in ICS telecom: the user specifies the number of arrays available in DL and UL
DL UL
Adaptive antenna systems in ICS telecom: the user specifies the number of arrays available in DL and UL
6 Traffic requirement for LTE
The four LTE traffic classes are:
Conversational (IP Voice) - In this type of application, a session last as long as the user makes a phone call.
HTTP Web navigation - Web traffic is nowadays the most important application used by the Internet community. The term web traffic comprises all Hypertext Transfer Protocol (HTTP) traffic generated during a session with a typical web browser like Firefox or Internet Explorer.
Streaming: Multimedia streaming services over the Internet are more and more popular. Movies, news, education and training, video conferences, personal streaming, such as webcams or security
surveillance, are only small parts of video streaming applications. FTP (TCP): Dedicated to the File transfer protocol.
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ICS telecom allows generating a population of mobile depending on the customer profile. The user can
specify per mobile according to each service type.
Population of LTE mobiles with ICS telecom
The throughput available at each sector, calculated according to the OFDMA permutation and the
number of data sub-carriers used, the UL/DL duration ratio, the modulation…
A variation of the contention ratio according to the hour of the day.
A random traffic calculation based on the Monte-Carlo Method
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7 Network design and analysis of LTE network with ICS telecom
ICS telecom allows managing all kind of calculations specific to the LTE technology that is to say :
Network coverage calculation.
DL and UL interference analysis based on SINR calculations.
Throughput prediction plots.
Automatic frequency assignment.
Automatic searching of best candidate.
Automatic optimization of the enodeB parameters (azimuths, tilt, antenna height, power control…) according to the coverage target.
Neighbor cell management: Automatic neighbor cell calculation.
Generation of mobiles with point t o point analysis.
Traffic analysis with Monte-Carlo simulator.
...
LTE coverage map with ICS telecom
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Interference + Best server mode map
Fig11: Traffic analysis with Monte-Carlo simulator with ICS telecom
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8 MBMS (Multimedia Broadcast Multicast Services)
ICS telecom supports the MBMS (multimedia broadcast Multicast service) for LTE.All the configurations (single-cell transmission or as multi-cell transmission) are fully take in charge by ICS telecom. In case of multi-cell transmission the cells and content are synchronized to enable for the terminal to soft-combine the energy from multiple transmissions. The MBMS concept also called SFN (Single frequency network)
SFN C/I map and best server map (interfered areas in pink)
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Software solutions in radiocommunications
ATDI IbéricaC/ Orense, 8 Piso 12-D (Nuevos Ministerios)28020 Madrid - EspañaTel. +34 91 598 21 36Fax +34 91 597 03 01E-mail : [email protected] : www.atdi.es
ATDI SA (International)8, rue de l'Arcade75008 Paris, FranceTel. +33 (0)1 53 30 89 40Fax +33 (0)1 53 30 89 49E-mail : [email protected] : www.atdi.fr
ATDI Inc. (Americas)1420 Beverly Road, Suite 140 McLean, VA 22101 - USATel. +1 703 848 4750Fax +1 703 848 4752Email : [email protected] www.atdi-us.com
ATDI Ltd. (Northern Europe)Kingsland Court, Three Bridges Road Crawley West Sussex RH10 1HL, United KingdomTel. +44 (0) 1293 522 052Fax +44 (0) 1293 522 521 E-mail : [email protected] www.atdi.co.uk
ATDI ESTBd. Aviatorilor, nr 59Bucharest - RomaniaTel. +40 21 222 42 10Tel./Fax +40 21 222 42 13E-mail : [email protected] www.atdi.ro
LLC ATDI Eurasia (Russia & CIS)Sadovnicheskaya str, 72 bld 1115035 Moscow - Russian FederationTel. + 7 499 929 96 10Tel./Fax + 7 499 929 90 01E-mail : [email protected] www.atdi.ru / www.atdi-eurasia.com
ATDI South Pacific PTY Ltd79 Macarthur Street - UltimoNSW 2007 - AustraliaTel. +61 (0)2 9213 2200Tel./Fax +61 (0)2 9213 2299E-mail : [email protected] www.atdi-pacific.com
ATDI UA in partnership with LISGmyri Str. 9-V, 6th porch, Office 211 (Ground floor),02068 Kiev - UkraineTel. +38 044 594 1343Fax +38 044 239 9813E-mail : [email protected] or [email protected] www.lissoft.com.ua
ATDI GermanyKurze Mühen 1 / Spitaler Hof20095 Hamburg - Germany Tel. +49 40 32901 226Fax +49 40 32901 100E-mail : [email protected] www.atdi-de.com
ATDI ScandinaviaKirkåsveien 381850 Mysen - NorwayTel. +47 69 89 58 00Fax +47 69 89 58 01E-mail : [email protected] www.atdi.no
