WCDMA

by

Sruthi Kodoth

PROJECT REPORTCourse Name: Wireless Systems

Course code: TSKS03

ISYLINKOPING UNIVERSITY

2016-05-09

Contents

1 Terminology 3

2 Background 42.1 Requirement of 3rd generation systems . . . . . . . . . . . . . . . . . . . . . 4

3 WCDMA 53.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4 Duplex Schemes 64.1 Time Division Duplex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4.1.1 Characterestics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64.2 Frequency Division Duplex . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5 Multipath Radio Channels and Rake Reception 7

6 Power Control 86.1 Inner loop power control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86.2 Open loop power control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86.3 Outer loop power control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

7 WCDMA handover 97.1 Soft/softer handover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97.2 Hard handover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

8 WCDMA channels 118.1 Physical channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118.2 Logical channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

8.2.1 Control channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128.2.2 Traffic channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

8.3 Transport channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138.3.1 Common Transport Channels . . . . . . . . . . . . . . . . . . . . . . 138.3.2 Dedicated Transport Channels . . . . . . . . . . . . . . . . . . . . . . 13

9 Diversity 149.1 Antenna Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149.2 Polarization Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

10 Modulation 15

11 Channel Coding 16

12 Spreading 1712.1 Uplink Spreading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1712.2 Downlink Spreading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

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13 Admission and Congestion Control 18

14 Conclusion 19

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1 Terminology

RNC - Radio Network ControllerCPICH - Common Pilot ChannelBLER - Block Error RateUE- User EquipmentSIR - Signal to Interference RatioHSDPA- High Speed Downlink Packet AccessEUL- Enhance Up LinkTPC - Transmit Power ControlUMTS- Universal Mobile Telecommunication SystemsSNR - Signal to Noise RatioTDD - Time Division DuplexFDD - Frequency Division DuplexQPSK - Quadrature Phase Shift KeyingQAM - Quadrature Amplitude ModulationDPDCH - Dedicated Physical Control ChannelDPCCH - Dedicated Physical Data Channel

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2 Background

Mobile communication has become an ubiquitous facet of modern-day life. This trend isbeing spurred by the explosive growth in the popularity of smartphones and tablets as wellas the deployment of high data- rate network standards (WCDMA, LTE). the demandson the mobile network imposed by millions of subscribers added with every passing daypresents formidable challenges. In order to support the large demand on capacity by millionof subscribers WCDMA is developed. WCDMA is one of the new standard of UMTS intendedto provide new spectrum to increase the cellular system capability.

2.1 Requirement of 3rd generation systems

In second generation communication system the data rate capability is restricted, howeverthird generation systems provides high data rate which ensures high quality of experience forthe users. The requirement of 3rd generation communication system includes

• Support of data rate up to 2Mbps.

• Different services with different quality on a single connection should be supported

• Offer variable bit rate to support bandwidth on demand

• Support for delay sensitive real time application and best effort packet service

• Provide good spectrum efficiency

• To enhance the coverage and balance the load, maintain inter system hand over.

• Different applications have different traffic in the uplink and downlink. Hence asym-metric data flow should be supported.

Compared to second generation systems , WCDMA includes transmit diversity to supportasymmetric data flow between uplink and downlink. In order to increase system throughputand guarantee quality of service, different radio resource management algorithm is requiredin third generation system. WCDMA is commonly operated on 2100MHz

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3 WCDMA

3.1 Introduction

Wide band Code Division Multiple Access is an improvement over the existing CDMA stan-dard and it uses a 5MHz wide radio signal with a chip rate of 3.84 Mcps. The WDCMAtechnology supports higher bit rate which helps to improve the quality of service. The em-ployed technique in WCDMA is not to separate users in the cell but instead separatingchannels in the cell. To support multiple services, each user should have separate channelsfor each service. WCDMA specific features are power control and soft handover. Powercontrol is one of the important feature to be employed in 3G in order to reduce the inter-ference between users because of frequency reuse. Each user should get the same amount ofpower to their handset in spite of the distance from the base station. If the amount of powerutilized by the handset is higher than required leads to an unequal shares of resources andthus creating an unnecessary interference to other users in the network. Hence the efficientpower control is an inevitable factor in improving the quality of service. WCDMA has anefficient power control mechanism that updates the power level in every 1500 seconds [1].To improve the performance of the network,soft handover feature is indispensable which al-lows the communication of users in two different cells in two or more different base stationssimultaneously [1].

3.2 Features

• It supports bandwidth on demand.

• Two modes of operations are being employed in WCDMA: (i) Frequency Division Du-plex(FDD) (ii) Time Division Duplex (TDD)

• Due to wide carrier band , it supports high data rates and increased mutipath diversity.

• Efficient packet access mechanism.

• Supports inter frequency handover.

• Reduces the interference and transmission power.

• It supports (i)HSDPA (High Speed Downlink Packet Access), the technique has beenintroduced in 3GPP release 5 which allows higher data speeds and capacity in thedownlink. (ii) EUL (Enhanced Uplink ) which has been introduced in 3GPP release 6.It is extended with additional transport channel and control to increase the performancein the uplink. Both features helps to increase the speed in the downlink and uplink.

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4 Duplex Schemes

UMTS TDD and FDD uses same 5MHz channel bandwidth.

4.1 Time Division Duplex

In time division duplex the downlink and uplink are separated by allocating different timeslots for the users in the same frequency band. It supports asymmetric flow of data transmis-sion. In UMTS TDD multi user detection is incorporated to enhance capacity and providehigh data rates. In UMTS TDD different logical channels are separated by utilizing separatespreading codes and at the receiver same code is use to recover the data.Total 15 time slotsare used in UMTS TDD where 3 slots are for overhead and remaining 12 slots used for userdata. For each user modulation and forward error correction can be altered to improve theoverall performance of the system. For UMTS TDD spectrum is allocated in the range of1900 MHz and 1920 MHZ , 2110MHz and 2170 MHz.

4.1.1 Characterestics

• Unpaired band utilization will helps to utilize the available spectrum efficiently.

• In TDDD system switching between transmit and receive will impose some amount oftime. Along with that some amount of time is involved for base station and mobiles toswitch between transmit and receiver. Hence guard band is required

• Base stations are synchronized to not to transmit when adjacent base station is receivingsince uplink and downlink share the same channel for transmission directions whichcause interference.

• Since uplink and downlink shares the same channel which utilizes same propagationcondition.

4.2 Frequency Division Duplex

Here separate frequency bands utilized at transmitter and receiver side. Due to the separatefrequency bands at receiver and transmitter, the sending signal and receiving signal do notinterfere each other. Spectrum allocation for FDD is in the range of 1920MHZ to 1980MHz and 2110MHZ and 2170 MHZ. Since the transmission and reception of signals aresimultaneous which needs two channels, spectrum availability is not utilized efficiently inFDD. In FDD it is difficult to allocate the spectrum in order to meet the capacity requirementin the uplink and downlink.

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5 Multipath Radio Channels and Rake Reception

During WCDMA transmission the data bits are encoded using forward error correction en-coder like convolution or turbo encoder. The modulation sysmbols are produced using theseencoded bits and symbols are distributed in such a way that each symbols can be denotedusing the chip sequence. The spread spectrum signal is combined to form the radio signaland transmitted.Rake receiver at the demodulator is utilized to extract the modulation from the receivedsignals. The main role of rake receiver is to minimize the effect of signal fading.Rake receivercontains many receiver sub-radios which are called finger which is responsible for tuning theindividual multi-path components. Each of these components decoded independently andfinally combined together.The propagation of radio waves is characterized by refraction, fading, multiple reflectionsand attenuation of signals. The receiver will receives the signals at different time instants.WCDMA separate multi path components and joined to form multi path diversity if thedifference in time instant between the multi-path components is larger than chip duration .For some delays many paths are approximately equal in lengths which leads to signal cancel-lation called fast fading . Due to fast fading the received data will contain error bits Hencesome measures should be deployed in WCDMA to overcome this. The fast power control andinherent diversity features helps to resolve the problem of fast fading. Coding, interleavingand retransmission protocol will add time diversity and redundancy in order to recover theuser bits.

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6 Power Control

The interference between users existing due to the utilization of same frequency and band-width by multiple users. Different user equipment will get different level of power based onhow far it situates from the base station. Hence power control is one of the crucial factorbehind the success factor of WCDMA. Power control feature is divided into three types isdiscussed in [2]

6.1 Inner loop power control

Power control is required to avoid the U.E is transmitting in high power as they move towardsbase station. The system must ensure that UE is communication with sufficient power levelto avoid interference between users. Inner loop power control is utilized once the connectionsetup is done. Main idea behind this technique to provide same signal to interference ratioto all U.E in the same cell. To counter balance for fading of signal, the inner loop powercontrol should be fast enough to adapt to the situation. Once dedicated channel is setup,the base station can control the power level of UE by sending power control messages usingTPC(Transmit Power Control) field of DPCCH (Dedicated physical control channel). Thepower can be adjusted by sending increase or decrease commands 1500 time per second.

6.2 Open loop power control

This technology is used to set the power initially while U.E making connection. The followingprocedures are included:

• U.E measures the received power over the CPICH

• The U.E also reads the base station transmit power of CPIH. U.E will get this infor-mation from the broadcast channel.

• U:E calculates the minimum value among the estimated power level to access the cell.Initiate the connection with the minimum power .

• The UE will gradually increase the power and retry if the initial attempt was a failure.

6.3 Outer loop power control

Outer loop power control is utilized to maintain the quality of communication by switchingthe value of signal to interference ratio for inner loop power control. RNC is responsiblefor setting the SIR target based on the received Block Error rate (BLER). Too much highquality will utilize resource inefficiently hence outer loop power control decrease SIR target.The RNC estimates the SIR target using block error rate and BLER quality target.

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7 WCDMA handover

Handover occurs due to mobility and user equipment mode change. When mobile devicemove from one location to another, the radio links and connections should adjust with outdropping the call. [3] discussed hand over in detail. Different kinds of handover is mentionedbelow.

7.1 Soft/softer handover

Handover occurs between the carriers of same frequency. In soft handover U.E is connectedto two or more RBS at the same time. UE constantly monitor the power level as it movesthrough different base station. Mobile station measures the signal level broadcasted fromdifferent base stations and maintains an active set of values and compares them with the setof thresholds. Based on the estimated information the network will request mobile station toadd or delete the from the active set. Softer handover is a special case of soft handover whereU.E is connected to two or more sectors belonging to the same base stations. Soft/softerhandover is a prominent part of efficient power control in WCDMA. Lack of soft/softerhandover feature leads to ineffecient power controlling mechanism as mobile moves from onecell to the neighbouring cell without being power controlled by the adjacent cell. Duringsoft/softer handover , channel between the base station and RNC (CPICH) will be measuredby the U.E. The events are occurred based on different scenarios:

• When the common pilot channel is not added into the active list. Radio link additionevent will be triggered

• Already included CPICH(common pilot channel)in the active list leaves from the range.Radio link deletion event will be triggered.

• The CPICH not included in the active list become stronger than which is in the activelist.Combined radio link addition and deletion event will be triggered.

7.2 Hard handover

Hard handover occurs between different operators utilizing different carrier frequency in-cluding handover to GSM. During hard handover un-noticeable break in communication willoccur. As the mobile is able to transmit in one frequency, when it moves towards differ-ent channel the connection is already broken and establish a new connection. Hence it isalso called inter frequency handover. Serving Radio Network Controller will generate themeasurement report and will sends the message for physical channel reconfiguration. Mea-surement report is based on the sequence of events. Sequence of events will be generatedby comparing frequency range to a certain threshold. If common pilot channel goes beyondcertain threshold, an event is triggered to generate new measurement report. Consequentlyit stop measurement on other WCDMA frequency range. Similarly these kind of events aretriggered when U.E transmission power is low. The inter frequency hand over will be sat-isfied when the frequency of U.E is low compared to the new frequency it is measuring on.Consequently U.E will generate new measurement report and an event will be triggered to

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RNC. RNC will updates with a physical channel reconfigurable message to UE about thenew frequency handover. U.E will update the reconfiguration complete message .

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L1/PHY L1/PHY

L2/MAC L2/MAC

L2/RLC L2/RLC L2/RLC L2/RLC

L3/RRC L3/RRC

PHYSICAL CHANNEL

LoGICAL CHANNEL

TRANSPORT CHANNEL

SIGNALLING RADIO BEARER

Figure 1: WCDMA channels

8 WCDMA channels

Figure 1 shows the different channels in WCDMA [4].

8.1 Physical channel

Physical channel carries data through the air. It can be divided into two parts: Higherlayer data is the coded and multiplexed transport channels. Physical layer data includespilot bit for channel estimation, transmit power control command(TPC) , other feed backinformation for closed loop transmit diversity, transport format combination indicator. Thephysical channel is communicated over the air through specific carrier frequency and usingexplicit spreading code. Different physical channels are:

• P-CCPCH- Primary common control Physical Channel: It carries broadcast channeland is used to broadcast information to all other users.

• SCH-Synchronization Channel: The channel utilized to search for cell availability andcommunication with synchronization information. It includes primary synchronizationchannel and secondary synchronization channel.

• S-CCPCH- Secondary Common Control Physical Channel: It carries forward accesschannel and paging channel.

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• PICH- Paging Indicator Channel: The physical channel utilized to save the devicebattery by informing the user equipment that the paging information will be sendingsoon.

• DPCH (UL and DL)- Dedicated physical channel in the downlink(DL):The physicalchannel utilized to transmit user data.

• PDSCH- Physical Downlink Shared Channel: The physical channel carries the downlinkpayload.

• PUSCH-Physical uplink shared channel: The physical channel used to carry the userdata. It utilizes QPSK and 16 QAM modulation technique(64QAM optional).

• PRACH - Physical Random access channel: The physical channel is utilized when UEcommunicates in non synchronized mode and it also permits the UE to synchronize thetiming between UE and eNodeB.

• PNBSCH- Physical NodeB Synchronization Channel: The channel used between eN-odeBs to provide time synchronization.

8.2 Logical channel

The channels used for communication between RRC and RLC/MAC layer.The logical chan-nels are differentiated into traffic channel and control channel.

8.2.1 Control channel

• Broadcast control channel: Broadcasting channel used to inform UR with all the net-work specifications.

• Paging control channel: Utilized to transport the paging information.

• Dedicated control channel:It is a point to point communication to carry dedicatedcontrol information in both directions.

• Common Control channel: Point to multipoint connection utilized in uplink and down-link to transfer control information.

8.2.2 Traffic channel

• Dedicated traffic channel: For each subscriber there is a dedicated traffic channel tosend user traffic to eNodeB and it is a point to point connection.

• Common traffic channel: It is point to multipoint connection used to transmit userdata to a group of specified U.Es.

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8.3 Transport channel

The transport channels are the service provided by the physical layer to MAC layer [5] . Theyare defined by how and with what characteristics the data is transported over the air. Eachtransport channel come along with Transport Format Indicator(TFI). The physical layercombines the different transport channels TFI indicator to transport format combinationindicator. Transport channels are of two types:

8.3.1 Common Transport Channels

• Broadcast channel(BCH): This channel broadcast cell and system information thathelps U.E to identify the cell.

• Paging Channel (PCH) : This channel carries paging procedure (sleep mode) used bythe network to establish connection to U.E.

• Random access channel(RACH): The channel used to gain access to system when UEtries for the first time.

• Forward access channel(FACH): The channel used to carry control information to U.Esinside the cell.

• High speed downlink shared channel(HS-DSCH): This channel is shared among multipleusers dynamically. It is flexible to change in code and modulation technique to adaptto the system.

8.3.2 Dedicated Transport Channels

• Dedicated channel: This channel is allocated to each U.E . It supports a speech channel.

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9 Diversity

The increased bandwidth utlized in WCDMA helps to resolve the multipath componentswhich gives more diversity and high capacity. Diversity technique is utilized to mitigate theeffect of degradation of radio signal due to shadowing, fading etc .

9.1 Antenna Diversity

Antenna diversity is suited for mobile station of large size and base station since diversitygain is small as diversity branches are closer. Receiver antenna diversity gives an averageof receiver’s noise opposed to fading and interference. Transmission antenna diversity canbe used to create multipath diversity where limited amount of multipath diversity is exist-ing.Transmission diversity is acheived by generating the same signal with th delay such thatrake receiver can separate it. Receiver antenna diversity is utilized to maximize the cellcoverage by increasing the limited noise range.

9.2 Polarization Diversity

Polarization technique is one of the diversity technique employed in WCDMA technologyfor downlink and uplink data flow. One of the advantage in polarization diversity is thatseparate physical antennas are not required for different diversity branches. In polarizationdiversity different signals with different polarization is send and received via antenna whereat the receiver diversity combining technique is utilized to provide a better quality signal.Basic principle of multi path diversity is to improve final signal quality by combining differentcomponent of the received signal. Maximum ratio combining(MRC) is the diversity techniqueemployed in signal processing. MRC is generally used for large phased array system whereeach received signal is assigned a weight based on the signal to noise ratio. Each of thereceived signal is added and yields the result

∞∑k=1

SNRk

where k is the received signal. Diversity function is implemented as a part of the radio accessbetween UE, RNC and base station depends on the direction of data flow and position ofnetwork element. Hence it is worth noting that diversity technique is extremely importantfor soft hand over feature .

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10 Modulation

WCDMA incorporates two modulation techniques namely dual QPSK (Quadrature PhaseShift Keying) and 16 QAM(Quadrature Amplitude Modulation). In 3GPP release 5 WCDMAprovides new feature by combining with HSDPA enhancement where QAM is coupled withHARQ (Hybrid Automatic Repeat Request) and AMC ( Adaptive Modulation and Coding). Some downlink physical utilizes QPSK or 16 QAM depending on the channel condition anddata rate. Conventionally, QAM is used to achieve high data rate in the downlink direction,dual QPSK is utilized in the uplink direction and QPSK is utilized in the downlink direction.In QPSK, the transmission of data is modulated by their carriers. Based on the differentphase shifts (0, 90, 180, 270) of a carrier 2 bits are modulated. Two carriers were used inQPSK namely In phase and Quadrature phase. 4 states of 2 bit binary code is representedby In phase from 0◦to 90◦and Quadrature phase of 180◦and 270◦.In QAM all constellation points are placed uniformly in square grid vertically and horizon-tally. Two branches of carriers are used in QAM with 90 degree phase difference, whereeach branch is modulated independently and transmit the data in the same physical channel.Compared to the 3GPP Release 4, in Release 5 QAM is combined with AMC increases thedownlink WCDMA data capability in several orders of magnitude. Though QAM upgradeupto 64QAM due to cost efficiency 16QAM in considered as feasible for UTRAN(UniversalTerrestrial Radio Access Network) applications.

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11 Channel Coding

One of the feature of WCDMA is that it has a flexible multirate data transmission schemewhich helps to provide different service based quality of service parameters and multipledata rates. Here channel coding, interleaving, data rate can be varied to gain different typeof quality of service. The channel coding scheme is a set of error correcting, rate match-ing, interleaving, transport channel which maps to the the physical channels. During eachtransmission time interval data arrives at multiplexing unit which is is a transport block set.Multi rate transmission involves adding CRC(Cyclic Redundancy Check) to the transportblock, combine the transport block with the segmentation of code block, Channel codingand rate matching, interleaving, segmenting into radio frames, multiplexing the transportchannels, segmenting the physical channel and finally mapping to the physical channels. Onthe transport block error detection achieved using CRC . The CRC is 24,16,12,8,0 and thehigher layers determines the length of the CRC. After adding the CRC the concatenationof transport blocks and code block segmentation is carried out. Code block segmentation isexecuted If the size of the number of bits in the transmission time interval is greater thanthe maximum size of the code blocks. The maximum size of the coding blocks depending thecoding scheme for eg:

• For convolutional coding it is 504

• For turbo coding it is 5114

• No channel coding it is unlimited

The equalization of radio frames has been achieved by padding the input data in such away that the output data can be segmented into equal size. When the transmission intervalis larger than 10ms the input data is mapped into consecutive radio frames which enablesinterleaving and thereby improves the spectral efficiency. Since WCDMA allows differentdata rates , the number of bits in the transport channel can be varied based on transmissiontime interval. The rate matching is performed by adapting the yielded symbol rate to thepossible symbol rate of the physical channel. One or more physical channel can be utilized totransmit the data. Physical channel segmentation separates the bits among different channelif more than one physical channel is employed.

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12 Spreading

Spreading is carried out using channelization code where every data symbol is mapped intodifferent chips which increases the bandwidth of the signal. In the downlink scrambling isused and in the uplink user separation is used.

12.1 Uplink Spreading

In uplink short and long codes are used. For the ease of execution of multi user receiver tech-nique short codes are used. Sort codes are of length 256 and long codes of length 241. Bothare truncated to form a 10ms frame. Code multiplexing used in uplink leads to parallel trans-mission of two channels and hence emphasis should be laid on modulated signal constellationand peak to average power ratio. The code multiplexing solution along with the scramblingcode results in a output back off requirement in the power amplifier which remains same forone QPSK signal. Single DPCCH(Dedicated physical Control Channel) and maximum of sixDPDCH(Dedicated Physical Data Channel) can be transmitted simultaneously.

12.2 Downlink Spreading

Downlink channel uses the same channelization code as uplink. Length of 218 has been usedfor scrambling but later it will truncate into 10 ms frame. Complex value code is generatedby adding the same truncated code with different time shifts. One primary scrambling isassigned to each cell. To reduce the cell search these scrambling code are divided into 512groups. There are 15 secondary scrambling codes are utilized along with primary scramblingcodes. Secondary scrambling codes are utilized when orthogonal channelization codes areinsufficient. Secondary scrambling codes can reduces the orthogonality between the channelcodes but however it is balanced by the spatial isolation given by the adaptive antennas.Primary scrambling code is utilised for transmission CPICH and CCPCH and secondaryscrambling along with the primary scrambling codes in the sets has been utilized for otherdownlink channels.

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13 Admission and Congestion Control

Multi path fading is a common problem in radio communications which causes distortionto the radio signals.As signals will take different paths and in vary length , the receiverwill receive the signals at different times which leads to phase distortion and intersymbolinterference during data transmission. Hence it is vital to incorporate necessary features inradio communications which reduce the effect of the above discussed problem. Authors of [6]discussed about the capacity challenges in WCDMA techiques due to the multi path fadingand interference problems. Load control is a prominent part of WCDMA since load, qualityand coverage are corelated.Increase in interference due to system load can affect the coverageof the cells and quality of service of the network. Utilizing load control mechanisms willhelp to increase the system capacity thereby ensuring the coverage and quality of service bycontrolling the key resources like power, downlink channelization code, channel elements etc. The admission control is done based on the load conditions in the air, uplink interference, downlink power and number of requested users. Admission control is able to distinguishbetween guranteed service and best effort service and hence will solve the problem of overloadsituations. Using these available services it will be allocating resources inside the cell. Henceit does not do admission control on common channel. Congestion control will reduce the loadsituation by using different scenarios

• Minimize the packet throughput traffic

• Handover to other WCDMA carrier

• Delaying the best effort service

• Bit rates of real time U.E’s is decreased

• Cancel the low priority calls in a controlled way

The authors in [7] discussed some of the congestion control techniques in WCDMA. Au-thors also provided the different quality of experience analysis when total load in differentiatedinto different services.

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14 Conclusion

WCDMA standard has enabled vastly increased data rates for cellular phone subscribers byleveraging the advantages of CDMA architecture. Use of chip codes at increased chip rateshelps simultaneous use of available spectrum with higher data throughput. It is worth notingthat successful implementation of WCDMA should regulate the output power levels in thenetworks.

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References

[1] B. Gestner and B. Persson. (2002) RNC3810−Ericsson’s first WCDMA radio networkcontroller. Ericsson.

[2] Power control fundamentals in WCDMA. online. telecomsource.

[3] 3GPP specification detail. online. 3gpp.

[4] 3G UMTS Data Channels. online.

[5] Quality of Experience for Mobile Data Networks. Online. Citrix.

[6] J. Y. K. Aulin and D. Jeremic, “Compressive sensing aided determination of WCDMAconstrained capacity,” in IEEE Int. Conf. Communications (ICC), June 2012, pp. 4072–4077.

[7] Congestion control in WCDMA with respect to different service class. online.

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