Imagination Is More Important Than Knowledge

Published Date: 02 Nov 2017

Chapter 1

Chapter 2

An Overview of HSDPA Evolution

Measure what is measurable, and make measurable what is not so.

- Galileo (1564 - 1642).

2.1 Introduction

HSDPA is rapidly growing and becoming a commercial deployment in numerous networks around the world. HSDPA is defined in 3GPP Release 5. HSDPA aims to increase both the user throughput as well as the system capacity for data service. The simplified transmission system of HSDPA is shown in Figure 2 [1]. The Node B scheduler sends data to the user by the shared downlink channel based on the UE channel quality report. Based on the outcome of the decoding the UE will then reply with an ACK/NACK message by the HS-DPCCH [1].

Figure 2: Simplified HSDPA transmission system [1].

The High Speed Downlink Shared Channel (HS-DSCH) [1] supports modulation and adapting coding. The Dual-Carrier HSDPA used 64QAM and 1/1 coding in Release 8.

The High Speed Signaling Control Channel (HS-SCCH) [1] is signaled the dynamic resource allocation to the users by the Node B scheduler (per 2 ms TTI). The HS-SCCH carried the following information's:

The addressing specific UEs like UE identity via a UE specific CRC [1].

Transport Format and Resource Indicator (TFRI), which identifies the transmission format and the scheduled resource [1].

For the combining process to identify redundancy versions the Hybrid-ARQ-related information use in HS-SCCH [1].

Up to 4 HS-SCCHs can monitor by a user [1].

The High Speed Dedicated Physical Control Channel (HS-DPCCH) [1] supports the HARQ and channel based scheduling for feedback signaling in the uplink. The HS-DPCCH carried the following information's:

Channel Quality Information (CQI) is used to inform about the instantaneous channel condition to the scheduler [1].

HARQ ACK/NACK is used to inform the decoding process to the sender and request for retransmission [1].

This chapter describes a short overview of HSDPA evolution features in 3GPP Release 7 and 8.

2.2 Overview of HSDPA Evolution

HSDPA was included in the 3GPP Release 5 then Release 7, 8.9,10 and 11 have brought a number of HSDPA evolution and improves network efficiency by providing major enhancement. The HSDPA Evolution work has improved and progressed in 3GPP in parallel to LTE work. Lots of technical solutions in HSDPA evolution are similar like LTE. HSDPA Evolution aims to improve end user performance by introduces different features that support reduce latency, higher data bit rates, improve support for VoIP, increase capacity and multicast services [3, 4].

Higher-order modulation (HOM): It introduced 64 QAM in the downlink to increases the peak data bit rate 14 Mbps to 21Mbps. Physical channel also modified to support new modulation scheme, larger transport block sizes and larger range channel quality indicator(CQI) [3, 4].

Multiple input, multiple output (MIMO): It defined in Release 7 and it using two streams for transmitting up. For extending HSDPA peak data bit rate to approximately 28 Mbps, each stream can use QPSK or 16QAM.In Release 8, for extends the HSDPA peak data bit rate to 42Mbps, each stream can use 64QAM [3, 4].

Continuous packet connectivity (CPC): The packet data users activity level depends over time so to avoid the delays with state transitions it remain with a dedicated connection(CELL_DCH) even when temporarily inactive. For packet data users its make the dedicated connection state more efficient. This effort is called Continuous packet connectivity (CPC) in Release 7. It consist two main features and they are UE DTX/DRX and HS-SCCH less operation. If there is no information to transmit in the uplink then UE DTX (discontinuous transmission from the UE) imposes UEs to switch off transmission of the dedicated physical control channel (DPCCH). Two benefits of this transmission are reduced interference and reduced battery consumption and it will increases uplink capacity in terms of number of users [3, 4].

Same as in the downlink if there is no information to receive then UE DRX (discontinuous reception at the UE) impose UEs to switch off their receivers. The benefit is to reduce battery consumption. The HS-SCCH less operation becomes significant when many small packets like VoIP packets are transported in the downlink. This less operation concept reduces code usage and reduces interference from the control signaling for increase the capacity in the downlink. In Release 7, the CPC concept supports the capacity for VoIP by around 10% in the downlink and 40% in the uplink [3, 4].

Layer-2 enhancements: New MAC protocol introduce in Release 7. The flexible sizes and segmentation of RLC (radio link control) PDU (packet data unit) supports MAC-ehs. The improvement of MAC multiplexing capabilities the RLC PDUs can carry data or signaling from different radio access carriers and can be multiplexed into a single MAC-ehs PDU. The continuous improvements of the enhancements made to the downlink protocol can be applied to the uplink protocol in Release 8. The flexible RLC PDU sizes improve and support the uplink coverage and helps reduce level-2 overhead and processing [3, 4].

Enhanced CELL_FACH: It has been activated in HSDPA for users to improved and support for faster switching and background traffic to continuous transmission state in Release 7. In CELL_FACH, the uplink is also improved by activating E DCH in Release 8 [3, 4].

Multicast/broadcast single-frequency network (MBSFN): The exact and same waveform from multiple cells for simultaneous transmission is called MBSFN. This is the way that the UE receiver can understand the multiple MBSFN cells as one large cell [3, 4].

Downlink-optimized broadcast (DOB): It’s introduced in 3GPP and one step further of MBSFN operation. DOB introduced as a special mode of 3.84Mbps time division duplex (TDD) operation in disjointed bands of spectrum [3, 4].

Advanced receivers: Receiver structures in Node-Bs and UEs are constantly improved and more complex features are added to HSDPA as products evolve. The result is for higher user data bit rates and improved system performance [3, 4].

For future Evolution and Releases of the specification, 3GPP introduced and considering Multi-Carrier operation and introduced more advanced receivers.

2.3 HSDPA 3GPP Evolution Diagram

Figure 3: HSDPA 3GPP Release evolution diagram

2.4 HSDPA Evolution Table

HSDPA Evolution Table 1 [4]:

3GPP Release Modulation MIMO Bandwidth Carrier Downlink Rate

Release 5 16 QAM NO 5 MHz 1 14 Mbps

Release 6 --------------Develop only in uplink---------------------------------------

Release 7 16 QAM 2×2 MIMO 5 MHz 1 28 Mbps

Release 8 64 QAM No MIMO 10 MHz 2 42 Mbps

Release 9 64 QAM 2×2 MIMO 10 MHz 2 84 Mbps

Release 10 64 QAM 2×2 MIMO 20 MHz 4 168 Mbps

Release 11 64 QAM 2×2 MIMO/ 40 MHz 8 336-672 Mbps

4×4 MIMO

2.5 Work Flow Diagram of this Thesis

Figure 4: Work flow diagram of this thesis

Chapter 3

Evolution of Multi-Carrier HSDPA

I have had my results for a long time: but I do not yet know how I am to arrive at them.

- Gauss, Karl Friedrich (1777 - 1855).

3.1 Introduction

In UMTS Release 99, WCDMA was specified 5 MHz of nominal carrier spacing with the chip rate of 3.84Mbps. After a number of evolution steps included in 3GPP releases. Until 3GPP Release 7, all the deployment were limited and the bandwidth also same like 5MHz. Release 8 fetched Dual-Cell HSDPA and Dual-Cell HSDPA can possess a single UE to receive on two adjacent carriers. In Release 9, Dual cell improves its uplink and downlink with combine the MIMO. In Release 10, Three and four carriers introduced in the downlink direction. Release 11 will specify support of eight carriers in the downlink direction. The overview of HSDPA multicarrier evolution is shown in Figure 5 [4]. The main benefits of multicarrier evolution are better tracking efficiency and higher data rates. The peak data rate of HSDPA carrier evolution is summarized in Table 2: eight carriers with MIMO give a theoretical maximum peak rate of 336 Mbps [4].

3 GPP Release 7: 3 GPP Releases 8-9:

UE can receive on single 5 MHz carrier UE can receive on two adjacent 5 MHz carriers

3 GPP Release 10:

UE can receive on four adjacent 5 MHz carrier

Figure 5: Overview of MC-HSDPA Evolution [4].

Without MIMO With MIMO

1 carrier 21 Mbps 42 Mbps

2 carriers 42 Mbps 84 Mbps

3 carriers 63 Mbps 126 Mbps

4 carriers 84 Mbps 168 Mbps

8 carriers 168 Mbps 336 Mbps

Table 2: Downlink peak data rates with Multi-Carrier HSDPA [4].

Multiband HSDPA also introduced in Release 9 where different frequency bands can be support in the two downlink carriers. Example is like 900 MHz in one carrier and 2100 MHz in another carrier. Release 10 also extended the downlink up to four carriers on two different frequency bands [7]. The multiband evolution is shown in Figure 6 [4].

3 GPP Release 7:

UE can receive on single band

900 MHz 2100 MHz

3 GPP Release 9:

UE can receive on two band

900 MHz 2100 MHz

3 GPP Release 10:

UE can receive on two bands with up to four carriers

900 MHz 2100 MHz

Figure 6: Overview of HSDPA multiband evolution [4].

In this chapter, a brief description is given about the evolution of 3GPP Multi-Carrier HSDPA. The main technical basis of their functionality and user gain also mentioned.

3.2 Dual-Cell HSDPA Release 8.

In Release 8, if the number of users is low then Dual-Cell HSDPA can double the user data rate because each user can utilize the two parallel frequencies. When the number of users increases then the probability will be low that each user can utilize the full capacity of both parallel frequencies. But even at high system load Dual-Cell HSDPA provides lots of capacity benefits for users compared to two single carriers [2]. The gains and principles of the Dual-Cell HSDPA are shown in Figure 7 [4].

Figure 7: Data rate gain of Dual-Cell HSDPA [4]

The following features are discussed about the capacity gain of Dual-Cell HSDPA:

Frequency domain packet scheduling gain: In both carriers of HSDPA, the UE provides separate CQI reports and no faded data or packets transmit on the frequency by the Node B packet scheduler. When moving some distance like tens of centimeters, the fast fading is uncorrelated and location dependent. Between two UEs, the fast fading is independent. The frequency domain scheduling and its principles shown in Figure 8 [4].For obtain capacity gains the Long Term Evolution (LTE) also uses frequency domain scheduling. LTE provides higher capacity gains by using the frequency domain scheduling with compared to HSDPA because HSDPA frequency resolution is 5 MHz and LTE is 180 kHz [4].

Figure 8: Frequency domain scheduling with DC-HSDPA [4].

Statistical multiplexing or tracking gain: Dual-cell HSDPA can be balanced the load between two frequencies with 2ms TTI resolution but the two SC-HSDPA needs for balanced the load redirections or slow inter-frequency handovers. So the load is not ideally balanced for the two SC-HSDPA [4].

Multiuser diversity gain: The proportional fair algorithm can be utilized by HSDPA packet scheduling in the time domain. When there is huge number of UEs then the HSDPA packet scheduling algorithm gives a higher gain. For the optimized scheduling, now Dual-Cell HSDPA allows and accepts the users from two frequencies [4].

3.3 Dual-Cell HSUPA Release 9.

To improve the uplink user data rates, the 3GPP Release 9 was include the Dual-Cell HSDPA. The difference between uplink and downlink Dual-Cell benefits is:

The Node B transmission power is much higher than the UE transmission power. The transmission power is high that’s why the uplink user data rate is low and limited than the downlink user data rate [4].

Frequency domain packet scheduling is not so simple in the uplink but in the downlink is so simple because there is similar fast CQI reporting [4].

3.4 Dual Cell HSDPA with MIMO in Release 9.

Multiple input, multiple output (MIMO) was introduced in 3GPP Release 7 and Dual-Cell HSDPA was introduced in Release 8. After the evolution steps this two combinations was introduced in Release 9. The true MIMO gain comes in Release 9 and it can double the peak data rate from 42 Mbps to 84 Mbps. In Release 7, the combination of MIMO + 64QAM was not defined so here the MIMO did not double the data rate. In Release 8, the MIMO did not combined with Dual-Cell HSDPA so MIMO did not worked here properly and did not double the data rate. Now we could say that before Release 9 MIMO deployments was not happened. Note that in Release 8, there was opportunity to had Dual-Cell HSDPA UEs and MIMO UEs on the same carrier but both features did not used a single UE [2, 4, 8].

3.5 Dual Band HSDPA in Release 9.

To extend two or more HSDPA carriers in one frequency band need huge spectrum space and it is not always possible to get enough spectrum space. Therefore many operators had updated HSDPA carriers on two frequency band. So at the same time, the UE were able to receive on carriers in separate bands and the total bit rate increased. This type of Dual Band HSDPA was introduced in Release 9 [2, 4, 5, 7].

The combinations of band are listed in Table 3. Some Asian markets and the European markets can use configuration 1 with Band I (=2100 MHz) combine with Band VIII (=900MHz band). The Americas market can utilize Band II (=1900 MHz) together with Band IV (= 1700/2100 MHz). Some Asian market can utilize Band I (=2100 MHz) and Band V (=850 MHz). The further band combinations like Bands I, II, IV, V and VIII was included in the 3GPP Release 10 [2, 4, 7, 8].

Table 3. Dual band HSDPA combinations in 3GPP Release 9 [4].

If the two frequency variations are developed at the site than the Dual band HSDPA will be easy and simple for the radio network. But the Dual-band HSDPA is much more difficult for the UE implementation. Normally the UEs support minimum two HSDPA frequencies but at the same time those two frequencies were not used. In the Dual band HSDPA, the UE have to receive on two frequencies at the same time and it will increase the RF complexity in the receiver as UE and both bands have to operate continuously and negligent of which band is transmitting in the uplink by UE [4, 5, 7].

The lower frequency provides much better propagation and it creates the coverage areas of the several bands and several sizes. Based on CQI reports from UE, the scheduling can be done dynamically between two bands with 2-ms resolution. The CQI reports straight away accept into account the influence of interference and noise. The Dual band is shown in Figure 9 [4].

Figure 9: Dual Band HSDPA [4].

The Dual band HSDPA was introduced for downlink. For transmission, the uplink used only one frequency band. Radio Network Controller (RNC) only decides which of the band will be used for the uplink transmission. Some time inter-frequency handover used in the uplink carrier and its depends on the coverage area because if the higher frequency is allocated for uplink and UE runs out of the coverage area than the lower frequency can be handed for transmission by uplink. LTE-Advanced also included multiband features same as like HSDPA multiband in Release 10 [4, 5, 7].

3.6 Three and Four Carrier HSDPA in Release 10.

Most countries used 2100MHz band by three or four operators and each operator get 15 or 20MHz band because the 2100MHz band is 60MHz in total. So the spectrum accepts HSDPA to use three or four carriers. After evolution of Dual Cell HSDPA the three or four carriers HSDPA was included in Release 10. It increases the user data rate and also increases the capacity gain like 5-10% in the full buffer case [2, 4, 5, 8, 10]. The benefits and data rate of 4C-HSDPA are shown in Figure 10 [4].

Figure 10: Data rate gain of 4C-HSDPA [4].

4C-HSDPA utilize 20MHz radio frequency in UE. For LTE UEs now 20MHz bandwidth is mandatory. So 4C-HSDPA and LTE can used similar radio frequency receiver.

3.7 Eight Carriers HSDPA in Release 11.

The 8-carrier HSDPA feature was introduced in Release 11 and its carrier aggregation reach up to 40 MHz bandwidth. The 8-carrier HSDPA can be transmitting simultaneously to a single UE. The all carriers do not need reside contiguous to each other on an adjacent frequency block and now it is possible that all aggregate carriers together from more than one frequency band [5].

The 8-carrier HSDPA is awaited to increase the peak HSDPA data rate by a factor of 4 compared to 2-carrier HSDPA. The 8-carrier HSDPA can be awaited to get similar gains as obtained by the other multi-carrier HSDPA features standardized in Release 8 to Release 10. The user bit rates will be increased and will leading to a clear progress in user experience. The combination of all resources will also raise the system capacity [5].

The framework will reuse in the standardization of 8-carrier HSDPA which was developed the previous rounds of multi-carrier standardization in 3GPP. The framework will be reused as much as possible to comfort implementation of the standard [5].

For uplink, the 8-carrier HSDPA used only one carrier. The CQI carries the uplink signaling and two HS-DPCCHs carried by ACK/NACKs. Transmit the associated signaling just like 4-carrier HSDPA solution in Release 10; the two Single Frequency (SF) 128 channelization codes will be used [5].

To manage the increased data bit rates, MAC-ehs required some change in L2 and the RLC SN space will be increased so overall window size will be increased. In 8-carrier HSDPA, each carrier can be configured independently by MIMO. Mobility can be managed and it based on the primary carrier [5].

The servings Node B can be handle dynamically switch off and on carriers using by HS-SCCH orders. The procedure is important to manage the increased number of carriers [5].

In Release 11 for 8-carrier HSDPA, the multi band combination has not been discussed so far [5].

3.8 UE Categories

UE categories were introduced for DC-HSDPA. The four categories were included for DC-HSDPA in Release 8 and four in Release 9. The highest peak rate for Release 8 is 42 Mbps. Release 9 used same modulations and coding with MIMO and it double the peak rate of 84 Mbps. Here summarized the UE categories for DC-HSDPA in Table 4 [4].

Table 4: UE categories for DC-HSDPA [4]

In Release 9 also developed the UE categories for DC-HSUPA and two categories were included. Table 5 summarized the UE categories for DC-HSUPA.

Table 5. UE categories for DC-HSUPA [4].

MIMO UE implemented by two antennas but The DC-HSDPA UEs can be utilized with one or two antennas. So the MIMO UE penetration will be lower than the DC-HSDPA UE penetration.

Chapter 4

Multi-Carrier HSDPA System Design

If you speed up any nontrivial algorithm by a factor of a million or so the world will beat a

path towards finding useful application for it.

-[Press et al. 2002]

4.1 Introduction

The UTRAN side of MAC architecture for Multi-Carrier HSDPA and possible receiver architecture for Multi-Carrier was introduced in 3GPP Release 8. In this chapter, a brief description is given about the UTRAN side of MAC architecture and protocols and also possible receiver architecture for Multi-Carrier HSDPA.

4.2 Mac Architecture

Figure 11: UTRAN side of MAC architecture for Dual-Carrier HSDPA [6].

A single MAC-ehs entity is shown in figure 11 [6]. Here under the same Node B, the UTRAN and UE can be support the DATA/HS-DSCH transmission/reception in more than one cell. So the little changes need on the Layer 2 design for Dual-Carrier operation. Each DATA/HS-DSCH channel has separate Hybrid ARQ entity. One Hybrid ARQ process per Transmission Time Interval (TTI) for single carrier and two Hybrid ARQ processes per Transmission Time Interval (TTI) for Dual-Carrier transmission/reception [8]. In the physical layer, two orthogonal DATA/HS-DSCH channels viewed as independent transmission on Dual-Carrier. Each channel has associated uplink and downlink signaling. Both carriers have separate transport block and both block transmitted different or same Transport Format Resource Combination (TFRC) on both carriers based on the Channel Quality Information (CQI) feedback and Hybrid ARQ received on the associated uplink DATA/HS-DSCH channel. The Hybrid ARQ retransmissions with the same Modulation Coding Scheme (MCS) will be transmitted as like the first transmission on the same Hybrid ARQ entity [2, 6, 8, 17].

4.3 Receiver Architecture

Figure 12: possible receiver architecture for Multi-Carrier HSDPA on adjacent carriers,

as In Dual-Carrier HSDPA in 3GPP Rel. 8 (assuming N = 2 carriers) [8].

Possible receiver architecture for Multi-Carrier HSDPA was introduced in Release 8. It is highly important that when introducing new features in existing standards than it should be implemented in cost-effective ways and should be successfully employed.

Multi-Carrier HSDPA implemented several architectural options. Most of the architecture were more or less durable depending on the deployment just like; spectrum allocation of the carriers of interest. The Multi-Carrier HSDPA in 3GPP Release 8 introduced only to contiguous carriers within the same band. As shown in Figure 12 [8], per antenna branch the contiguous carriers enable the use of a single Radio Frequency (RF) chain in the receiver and the carriers operate at 10 MHz bandwidth. In two Radio Frequency (RF) chains each one operates 5 MHz bandwidth. The scenario is separate spectrum allocation but multiple Radio Frequency (RF) chains may be the desired architecture if the carriers reside in different frequency bands than the UE have to operate in Single-Carrier mode or Multi-Carrier mode and for this the analog receiver filters need to be implemented as separate fixed filters or tunable with several bandwidth. This case is similar like an LTE receiver and it can be able to operate different bandwidth just from 1.4 MHz up to 20 MHz So the same Radio Frequency (RF) architecture is may be possible to use for Multi-Carrier HSDPA + LTE capable device for both radio access standards [8].

Chapter 5

Simulation Model and Parameters

I hear and I forget.

I see and I remember.

I do and I understand.

-Confucius (551 BC - 479 BC).

In this chapter the novel approaches to evaluate the performance of Multi-Carrier HSDPA compare with Single-Carrier HSDPA are described. Two type simulation models is applied 1st one is queuing system model and 2nd one is link level simulation model and the key related parameters for both model are also described.

5.1 Queuing Model

A time-dynamical simplified traffic model is applied for this simulation. Data arrive to the model according to Poisson process and its positions are random consequent to a uniform distribution.

Assuming a files have fixed size f [bits] and file arrival intensity λ [Mbit/s/sector],the offered load per sector is λf [Mbit/s/sector] and the per packet user throughput is f/T [Mbit/s] (where T is the time that spent in the model for a packet of size f, including transmission and queuing time).

5.1.1 Single-Carrier Model

5.1.2 Multi-Carrier Model

5.2 Link Level Model

This model are basically a software implementation of one or multiple links between the Evolved base station (eNodeB) and the User Equipments (UEs), with a channel model to reflect the actual transmission of the waveforms generated. This results in very computationally intensive simulations, as transmitter and receiver procedures, which are normally performed by specialized hardware, as well as the generation of appropriate channel coefficients, are then performed in software.

Link level Simulation model is divided into three basic building blocks, namely "transmitter (TX)," "channel model"and"receiver (RX)" (see Figure 15). Depending on the type of simulation, one or several instances of these basic building blocks are employed. The transmitter and receiver blocks are linked by the channel model and evaluate the transmitted data, while signaling as well as UE feedback is assumed to be error free, but with a configurable-delay Uplink (UL).

Figure 15: Functional block diagram of the structure of the "HSDPA Link Level Simulator"

5.2.1 Transmitter Model

The layout of the transmitter is shown in Figure 16 [14], and depicts the implementation of the transmitter based on UE feedback values; a scheduling algorithm assigns each UE specific Resource Blocks (RBs) a Modulation and Coding Scheme (MCS), and an appropriate pre-coding matrix/number of spatial layers. A discrete set of coding rates specified as Transport Block (TB) sizes with 4-QAM, 16-QAM, or 64-QAM modulation alphabets, can be employed.

Figure 16: HSDPA Downlink (DL) transmitter structure of the "HSDPA Link Level

Simulator" [14]

5.2.2 Channel Model

The "HSDPA Link Level Simulator" supports both block-fading and fast-fading channels, which are used for downlink transmissions. In the block-fading case, the channel is constant for the term of one sub-frame (1 ms). In the fast-fading case, time-correlated channel impulse responses are generated for each sample of the transmit signal. The following options are considered as channel models:

1. Additive White Gaussian Noise (AWGN);

2. Flat Rayleigh fading;

3. Pedestrian A;

4. Pedestrian B;

5. TU;

6. Vehicular A;

5.2.3 Receiver Model

The receiver implemented in terms of receiver algorithm, channel estimation, and feedback calculation, among others. The structure shown in Figure 17 [14]; after the Cyclic Prefix (CP) removal and FFT, the RBs (Resource block) assigned to the UE are disassembled and passed on to the receiver, which in parallel receives information from the channel estimator and pre-coding signaling. The detected soft bits are subsequently decoded to obtain the data bits and figures of merit, such as throughput, SNR. The simulator currently supports Zero Forcing (ZF),) as detection algorithms; and regarding channel estimation, four different types of channel estimator are supported: (i) Least Squares (LS), (ii) Minimum Mean Square Error (MMSE), (iii) approximate LMMSE, and (iv) genie-driven (near) perfect channel knowledge based on all transmitted symbols. We used MMSE for channel estimation. Then the results from channel estimation, feedback calculation can be performed, which includes the Channel Quality Indicator (CQI) for all modes, the Rank Indicator (RI) for the Spatial Multiplexing (SM) modes and additionally the Pre-coding Matrix Indicator (PMI) for the CLSM mode. Together with ACK/NACK reports, this information forms the UE feedback, which is sent back to the eNodeB via a configurable-delay error-free channel.

Figure 17: HSDPA Downlink receiver structure of the "HSDPA Link Level Simulator" [14].

5.3 Simulation Parameters

5.3.1 Queuing Model Parameters

Parameter

Value

File arrival process

Poisson process

File Size

500 kB

Arrival intensity, λ

14.4 Mbps

Service rate, µ

28.8 Mbps

Table 6: Queuing model parameters

5.3.2 Link Level Model Parameters

Table 7: Link level parameters

Parameter

Value

UE (User equipment)

1

BS (Base Station)

1

Subframes

500

CQI

4

UE Receive Antenna(1 for single carrier)

2

UE Receiver

ZF (zero Forcing)

Channel Filtering

Block Fading

Channel type

AWGN, Flat Rayleigh, PedA, PedB, Vehicular A, TU

UE speed

3 Km/h

Bandwidth

5 MHz

Speed of light

299792458 m/s

HARQ

8

Max HARQ

2

Simulation type

parallel

Modulation

16 QAM and 64 QAM

Scheduler type

Fixed

Scheduler Assignment

Semi Static

Scheduler CQI

Set

Scheduler PMI

0

Up link delay

0

Channel Matrix Source

Generated

UE LLR Clipping

100

UE Config. Turbo Iterations

8

UE Config. Channel Interpolation method

Linear

UE Config. Autocorrelation Matrix type

Ideal

UE Config. Realization Number

0

UE Config. Realization Total Number

20

UE Config. Cyclic Delay Diversity (CDD)

0

UE Config. PMI Feedback Granularity

6

UE Config. CQI Feedback Granularity

6

UE Config. PMI Feedback

True

UE Config. Timing Offset

23

UE Config. Timing Sync. Method

Perfect

UE Config. CQI Feedback

True

UE Config. Predict

False

UE Config. Carrier Frequency Offset

Pi

UE Config. Perfect Frequency Sync.

True

UE Config. SINR Averaging Method

MIESM

Channel Mode Config. Interpolation Method

Shift to nearest neighbor

Channel Mode Config. Correlation for RX

0.3

Channel Mode Config. Correlation for TX

0.3

Channel Mode Config. Number of Sin Realization

10

Channel Mode Config. Time Correlation

Independent

Use PBCH

False

Use PDCCH

False

5.4 SNR Definition

In a transmission system the SNR γ is the key factor of link error prediction and measurement key for Channel Quality Information (CQI).

The HSDPA Link Level simulator SNR γ is defined as follows:

The Tx-signal vector, X = ,

where with k [1,...,] is the symbol(Tx) and it sent from the k-th Tx-

antenna (.......... number of Tx-antennas).

We get,

– the total Tx-power, = trace() = trace (E{}) = 1

– the Tx-power per Tx-antenna, = E{} =

H defines the channel matrix H, with = (... number of Rx-antennas)

v defines the noise vector v and its size with respect to the Fast Fourier Transform (FFT) and the number of subcarriers before the detector, where vec(v)

n defines the noise vector n after the FFT, where vec(n)

Channel Mode holds the Rx-signal vector y = Hx + v

– We can derive the receive SNR (before the detector),

= = = [14, 20].

– Where the SNR after the FFT becomes,

= = = [14, 20].

Chapter 6

Simulations Result

One should always generalize.

(Man muss immer generalisieren)

- Jacobi, Carl (1804 - 1851).

In this chapter , the simulation results graph for Multi-Carrier compare with Single-Carrier is given and also described the results summary .

6.1 Queuing Model Result

Figure18: User Throughput for Single and Dual-Carrier HSDPA as a function of Offered

load

6.1.1 Results Summary

In figure 1: The average user throughput is drawn as a function of offered load (average sector throughput).The performance is depicted for Single Carrier HSDPA and Dual-Carrier HSDPA. The Multi-Carrier HSDPA system configurations with N carrier fetch the desired N-fold gain in average user throughput as compared to the Single-Carrier HSDPA system with a same number of loads. In figure 1 the same offered load, the Multi-Carrier HSDPA raise the user throughput by the factor N. This gain can also expressed in conditions of supported offered load for an offered quality service level or channel conditions. So the gain depends on the offered load. If the offered load is high than the fewer resources are free so gain is low but the Dual-Carrier gain is higher than the Single-Carrier. If the offered load is low than the Dual-carrier gain is double then Single-Carrier.

6.2 Link Level Model Results

6.2.1 AWGN Channel Model Result

Figure 19: Throughput for different modes as a function of SNR (AWGN)

This subsection discusses the results obtained using AWGN channel model. Figure 19 shows the Link level performance comparison between the Multi-Carrier HSDPA and the Single-Carrier HSDPA. The results are obtained by using following settings: Single-Carrier and Multi-Carrier both used MMSE for channel estimation, block fading channel filtering used between all transmitters and receivers. zero forcing used as detection algorithm for UE receiver and UE speed is 3 km/h. 500 sub-frames or TTIs used for simulation. Single-Carrier used 16QAM and Multi-Carrier used 64QAM modulation. In Figure 19 the results indicate that the peak rate is almost 40 Mbps for Multi-Carrier and almost 10 Mbps for Single-Carrier so the Multi-Carrier throughput is higher and better than the Single-Carrier HSDPA.

6.2.2 Flat Rayleigh Channel Model Result

Figure 20: Throughput for different modes as a function of SNR (Flat Rayleigh)

This subsection also discusses the results obtained using Flat Rayleigh channel model. Figure 20 shows the Link level performance comparison between the Multi-Carrier HSDPA and the Single-Carrier HSDPA. The results are obtained by using following settings: Single-Carrier and Multi-Carrier both used MMSE for channel estimation, block fading channel filtering used between all transmitters and receivers. zero forcing used as detection algorithm for UE receiver and UE speed is 3 km/h. 500 sub-frames or TTIs used for simulation. Single-Carrier used 16QAM and Multi-Carrier used 64QAM modulation. In Figure 20 the results indicate that the peak rate is almost 40 Mbps for Multi-Carrier and almost 10 Mbps for Single-Carrier so the Multi-Carrier throughput is higher and better than the Single-Carrier HSDPA for this channel.

6.2.3 PedA Channel Model Result

Figure 21: Throughput for different modes as a function of SNR (PedA)

In this subsection discusses the results obtained using tap-delay based channel model PedA. Figure 21 shows the Link level performance comparison between the Multi-Carrier HSDPA and the Single-Carrier HSDPA. The results are obtained by using following settings: Single-Carrier and Multi-Carrier both used MMSE for channel estimation, block fading channel filtering used between all transmitters and receivers. zero forcing used as detection algorithm for UE receiver and UE speed is 3 km/h. 500 sub-frames or TTIs used for simulation. Single-Carrier used 16QAM and Multi-Carrier used 64QAM modulation. In Figure 21 the results shows that the peak rate is almost 40 Mbps for Multi-Carrier and almost 9.9 Mbps for Single-Carrier so the Multi-Carrier throughput is higher and better than the Single-Carrier HSDPA.

6.2.4 PedB Channel Model Result

Figure 22: Throughput for different modes as a function of SNR (PedB)

In this subsection also described the results obtained using tap-delay based channel model PedB. Figure 22 shows the Link level performance comparison between the Multi-Carrier HSDPA and the Single-Carrier HSDPA. The results are obtained by using same settings as previous channel PedA. In Figure 22 the results shows that the peak rate is almost 35 Mbps for Multi-Carrier and almost 10 Mbps for Single-Carrier so the Multi-Carrier user throughput is better than the Single-Carrier HSDPA for this channel model.

6.2.5 TU Channel Model Result

Figure 23: Throughput for different modes as a function of SNR (TU)

This subsection discusses the results obtained using tap-delay based TU channel model. Figure 23 shows the Link level performance comparison between the Multi-Carrier HSDPA and the Single-Carrier HSDPA. The results are obtained by using following settings: Single-Carrier and Multi-Carrier both used MMSE for channel estimation, block fading channel filtering used between all transmitters and receivers. zero forcing used as detection algorithm for UE receiver and UE speed is 3 km/h. 500 sub-frames or TTIs used for simulation. Single-Carrier used 16QAM and Multi-Carrier used 64QAM modulation. In Figure 23 the results shows that the peak rate is almost 35 Mbps for Multi-Carrier and almost 10 Mbps for Single-Carrier so the Multi-Carrier user throughput is higher than the Single-Carrier HSDPA for this channel model.

6.2.6 VehA Channel Model Result

Figure 24: Throughput for different modes as a function of SNR (VehA)

This subsection also discusses the results obtained using tap-delay based VehA channel model. Figure 24 shows the Link level performance comparison between the Multi-Carrier HSDPA and the Single-Carrier HSDPA. The results are obtained by using following settings: Single-Carrier and Multi-Carrier both used MMSE for channel estimation, block fading channel filtering used between all transmitters and receivers. zero forcing used as detection algorithm for UE receiver and UE speed is 3 km/h. 500 sub-frames or TTIs used for simulation. Single-Carrier used 16QAM and Multi-Carrier used 64QAM modulation. In Figure 24 the results shows that the peak rate is almost 37 Mbps for Multi-Carrier and almost 9.9 Mbps for Single-Carrier so the Multi-Carrier user throughput is higher and better than the Single-Carrier HSDPA for this channel model.

6.2.7 Results Summary

In figure 19,20,21,22,23,24 the throughput is plotted as a function of SNR in different transmission modes. Six different channel types are investigated here like AWGN, Flat Rayleigh, PedA, PedB, Vehicular A, and TU channels. In all cases the UE speed was 3 km/h and block fading filtering used between all transmitters and receivers. It is interesting that the peak rate of all different transmission modes is almost same like Release 5 and Release 8 in 3GPP for Single-Carrier and Multi-Carrier HSDPA. The peak rate in release 5 for single carrier is 14Mbps and in release 8 for Multi-Carrier is 42Mbps. The simulation results peak rate for all channels is given here Table 8.

Channel 

AWGN

Flat Rayleigh

PedA

PedB

VehA

TU

Peak rate for Single-Carrier(Mbps)

10

10

9.9

10

9.9

10

Peak rate for Multi-Carrier(Mbps)

40

40

40

35

37

35

The observation of all the simulated figure and results, the peak rate of Multi-Carrier HSDPA is higher and better than Single-Carrier HSDPA as a function of SNR.

Chapter 7

Summary and Conclusion

What we know is not much. What we do not know is immense.

-de Laplace, Pierre-Simon (1749 -1827).

The extreme growth of wireless data usage is leading the continuing evolution of today’s mobile broadband networks and HSPA has introduced a base for high speed data connectivity in more than 150 countries with almost 412 commercial networks and over 700 million subscribers worldwide. The Multi-Carrier HSDPA is the natural and greatest economical evolution for HSPA. The Multi-Carrier HSDPA allows operators and subscribers to make the highest efficient use of their existing investments and assets in network, spectrum and devices at low cost. The Multi-Carrier HSDPA increased the network capacity and now operators able to offer voice services and mobile broadband at low cost. The Multi-Carrier HSDPA enhances the end user experience by increase the data rates, lower latency, increase talk time.

HSDPA technologies defined in 3GPP Release 5 than continuing evolution of HSDPA, in Release 7 introduced Multiple Input Multiple Output (MIMO) and Higher Order Modulation (HOM) techniques to increase the peak data rate. Other features also introduced in Release 7 such as Continuous Packet Connectivity (CPC), Layer-2 enhancement, Multicast/broadcast single-frequency network (MBSFN), Enhanced CELL_FACH, Advanced receivers and Downlink-optimized broadcast (DOB). Evolving HSDPA continued to increase the peak data rate in Release 8 by introduced Dual-Carrier Operation. The Dual-Carrier operation combining the existing features with 64 QAM increase the peak data rate up to 42 Mbps. In Release 9 introduced Dual-Carrier with MIMO and increased the peak data rate up to 84 Mbps and also introduced Dual-Band HSDPA. Release 10 introduced four carriers HSDPA and can utilize up to 20 MHz bandwidth over two frequency bands. The peak rate reached up to 168 Mbps. In Release 11 introduced 8-Carrier HSDPA and can utilize up to 40 MHZ bandwidth with 4-Branch MIMO. The peak rate is 336 Mbps by using 2×2 MIMO and 672 Mbps by using 4×4 MIMO.

In this thesis works the HSDPA evolution and the multi-Carrier HSDPA evolution have been studied and discussed. The MAC architecture and possible receiver architecture for Multi-Carrier HSDPA also discussed. For performance evaluation, two type simulation models are developed to evaluate the user throughput performance with compare the Single-Carrier HSDPA. The first model was queuing system model where data arrived to the system according to Poisson process and positions are random according to a uniform distribution and performance measured as a function of offered load (average sector throughput). The second model was link level simulation model which were basically a software implementation of one or multiple links between the Evolved base station (eNodeB) and the User Equipments (UEs), with a channel model to reflect the actual transmission of the waveforms generated and performance measured as a function of SNR.

The first simulation model results shows that for same offered load the Multi-Carrier HSDPA achieves better user throughput with compare the Single-Carrier HSDPA. The second simulation model results shows that for different channel the Multi-Carrier HSDPA peak rate was twice than Single-Carrier HSDPA.