UMTS overview Tong quan mang 3G

Development of Mobile communication st Generation nd rd Generation Generation 1990s (digital) current (digital) 1980s (analog) GSM WCDMAFDD AMPS CDMA IS95 TACS Voice to Broadband Analog to Digital NMT CDMA 2000 D-AMPS WCDMA TDD OTHERS PDC AMPS = Advanced Mobile phone service GSM=Global system for Mobile Communications TACS=Total Access Communications Systems D-AMPS=Digital-AMPS NMT=Nordic Mobile Telephone PDC=personal digital cellular Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW (81) Ericsson Internal History of 3G  Based on the IMT-200 performance objectives and frequency allocation the ITU-R formally requested a submission of RTT proposals with a closing date at the end of July 1998  By the closing date , there were a total of 10 RTT proposals were submitted from Europe , United states , Japan , Korea and, China All these proposal where accepted  Five RTT for IMT2000 • WCDMA FDD • CDMA2000 (1X-EV-DO and 3X modes) • WCDMA-TDD • UWC-136 (based on D-AMPS) • DECT  Only three 3G network implemented and currently deployed 1-CDMA 2000 (1X-EV-DO) 2-WCDMA FDD (UMTS FDD) 3-WCDMA TDD (UMTS TDD) Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW (81) Ericsson Internal 3G standardization organizations  Standardization organizations such as 3GPP, 3GPP2 were established WCDMA CDMA2000 3GPP 3G system 3GPP2 FDD/TDD mode Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW (81) Ericsson Internal Frequency allocation for IMT2000 WARC in 1992 230MHz in 2GHZ Band was allocated to IMT2000 IMT-2000 1800 IMT-2000 1900 2000 1885 2010 1980 ITU MSS IMT-2000 1895 1918 2100 1980 2025 MSS (Reg.2) 2010 2025 2200 2110 2170 2155 MSS IMT-2000 MSS (Reg.2) 2110 2170 Japan PHS Europe/ 1880 Australia IMT-2000 1900 1920 1980 DECT 1850 MSS UMTS 1910 2010 MSS 2025 IMT-2000 2110 MSS 2170 UMTS UMTS 2025 1990 1930 IMT-2000 2110 MSS 2150 2165 USA PCS MSS Unlicensed MSS MSS: Mobile Satellite Service Prep: Vikash Gupta Reserve Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW (81) Ericsson Internal MHz Frequency allocation for IMT2000  Additional (2nd of June, 2000) WRC2000 Conference has decided to allocate additional bands for IMT-2000, 800MHz, 1.8GHz, and 2.5GHz Band 2010 800 2000 1500 1000 960 806 1710 1885 2500 2025 1980 2690 IMT-2000 2110 GSM 880 960 1710 1990 (Current) PDC 810 958 1429 1513 (Current) : Additionally assigned for IMT-2000 Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW (81) Ericsson Internal MHz 2170 UMTS FDD and TDD FDD (Frequency Division Duplex) f 1: for k Up Lin L Down f 2: for ink Mobile Terminal Base station TDD (Time Division Duplex) o Up & D f 1: for k wn Lin TS TS Up Down Mobile Terminal Base station TS: Time slot Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW (81) Ericsson Internal Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW (81) Ericsson Internal Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW (81) Ericsson Internal UTRAN Architecture Prep: Vikash Gupta Appr: Sukhpreet Singh Checked: Rev: PA1 Date: 2016-08-30 UMTS OVERVIEW (81) Ericsson Internal UTRAN Architecture Prep: Vikash Gupta Appr: Sukhpreet Singh Checked: Rev: PA1 Date: 2016-08-30 UMTS OVERVIEW 10 (81) Ericsson Internal Traffic volume measurement reporting criteria Contains the measurement reporting criteria information for a traffic volume measurement Event 4a: Transport Channel Traffic Volume [15] exceeds an absolute threshold Event 4b: Transport Channel Traffic Volume [15] becomes smaller than an absolute threshold Events 7X Event 7a: The UE position changes more than an absolute threshold Event 7b: SFN-SFN measurement changes more than an absolute threshold Event 7c: GPS time and SFN time have drifted apart more than an absolute threshold Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 67 (81) Ericsson Internal Compressed Mode Operation Compressed mode is a physical layer function that allows the UE to temporarily tune to another frequency, and measure the RF environment of another UMTS frequency (e.g IFHO) or another technology (e.g IRAT), while maintaining an existing dedicated channel Unlike TDMA type air interfaces, the WCDMA physical frame does not contain any idle or unused slots to make measurements on other frequencies This is not an issue if a UE has a dual Transceiver, which would allow the second receivers to make measurements while the first receiver is processing the 10 millisecond frames However, most UEs not contain dual transceivers (at this time), thus requiring an alternate means for a single transceiver UE to make measurements on other frequencies In the case of Ericsson, compressed mode may take one of two forms depending on the radio bearer combination at the measurements on other frequencies are taken If the radio bearer contains any delay sensitive services (e.g circuit switched voice), then SF/2 is utilized If it is not critical to delay the data flow (e.g interactive or background packet switched data) then Higher Layered Scheduling (HLS) is used Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 68 (81) Ericsson Internal Halving the Spreading factor (SF/2) Method If SF/2 is required, the spreading factor (or OVSF) is reduced to half of its typical value For example, a radio bearer containing an AMR 12.2k utilizes a 128 OVSF code When compressed mode is enabled, the spreading factor will be reduced to a 64 bit OVSF This allows a transmission gap of up to seven slots (of the fifteen slots per frame) to be available for measurements on other frequency However this 50% reduction in the spreading factor has many side effects To maintain the appropriate Bit Error Rate (BER), and counter the reduced processing gain, the power of the compressed frame will have to be increased by approximately dB This is illustrated in the following figure of a compressed mode transmission from 3GPP TS 25.212 In addition to downlink power utilization, compressed mode will also affect capacity by consuming more codes in the downlink, increasing channel element usage, and increasing uplink noise rise due to increased UE transmit power Because of these side effects, care must be taken to ensure that UEs not unnecessarily trigger compressed mode In addition, the time spent in compressed mode should be minimized One frame (10 ms) Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 Transmission gap available for inter-frequency measurements UMTS OVERVIEW 69 (81) Ericsson Internal Higher Layered Scheduling (HLS) Method In the case of HLS, the transmission gap is generated by simply reducing the user throughput in the higher layers This is achieved in Layer where the MAC utilizes a subset of the available transport format combinations (TFC) within the transport format combination set (TFCS) For example, the transport block set size for a PS 64 kbps transport channel may contain 0, 1, 2, or transport blocks of 336 bits within every 20 ms transport time interval (TTI) By only utilizing 0, 1, or transport blocks every TTI, a transmission gap of up to slots can be generated, while maintaining a maximum throughput of 50% of the original transport channel Unlike the SF/2 method, HLS does not require additional power, code usage, channel element usage, or UE transmit power to achieve compressed mode operation Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 70 (81) Ericsson Internal Power Control Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 71 (81) Ericsson Internal Power control As with any CDMA system it is essential that the base station receives all the UEs at approximately the same power level If not, the UEs that are further away will be lower in strength than those closer to the node B and they will not be heard This effect is often referred to as the near-far effect To overcome this the node B instructs those stations closer in, to reduce their transmitted power, and those further away to increase theirs In this way all stations will be received at approximately the same strength It is also important for nodeBs to control their power levels effectively As the signals transmitted by the different nodeBs are not orthogonal to one another it is possible that signals from different ones will interfere Accordingly their power is also kept to the minimum required by the UEs being served To achieve the power control there are two techniques that are employed: open loop; and closed loop Open loop techniques are used during the initial access before communication between the UE and node B has been fully established It simply operates by making a measurement of the received signal strength and thereby estimating the transmitter power required As the transmit and receive frequencies are different, the path losses in either direction will be different and therefore this method cannot be any more than a good estimate Once the UE has accessed the system and is in communication with the node B, closed loop techniques are used A measurement of the signal strength is taken in each time slot As a result of this a power control bit is sent requesting the power to be stepped up or down This process is undertaken on both the up and downlinks The fact that only one bit is assigned to power control means that the power will be continually changing Once it has reached approximately the right level then it would step up and then down by one level In practice the position of the mobile would change, or the path would change as a result of other movements and this would cause the signal level to move, so the continual change is not a problem Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 72 (81) Ericsson Internal Power Control Any WCDMA system is limited by interference and it is important to minimize the interference level, since the lower the interference, the better the network capacity is The intent of Power control is to allow as many users as possible into the WCDMA network, while keeping the interference caused by these users to a minimum Power control aims at using the minimum signal to interference ratio (SIR) required for the quality of the connection to remain sufficient Power control provides protection against large changes in shadowing, immediate response to fast changes in signal and interference levels It is also needed to cope with the near-far problem found in WCDMA systems, and to bring the SIR back close to the target SIR as fast as possible after each transmission gap in compressed mode The two main capabilities of Power Control in a WCDMA system are as follows: To maintain the quality of connections (including common channels needed, for example, for call access) To minimize the transmitted power in both uplink and downlink Power Control works on a connection basis Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 73 (81) Ericsson Internal Power Control There are three different types of power control in UMTS Open Loop: Open Loop power control is used when no feedback mechanism is possible An estimate of the required power is made from measurements and system information This is used for initial network access and finding initial power settings during dedicated mode Closed Inner Loop: This power control technique uses a fast feedback mechanism to request an increase or decrease in output power based on the difference between the target and measured SIR The feedback is provided via Transmit Power Control (TPC) bits on the DPCCH channel 1500 times per second Inner loop power control exists in both the uplink and downlink Closed Outer Loop: Outer loop power control is used to set the target SIR that is used during inner loop power control For downlink power control this is set in the UE by an algorithm that is proprietary to the UE manufacturer For uplink power control it is set by the RNC The key difference between closed and open loop is the feedback cycle Closed loop relies on feedback from the receiving node to adjust the power at the transmitting node Open loop has no feedback on the amount to increase or decrease it’s transmit power Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 74 (81) Ericsson Internal UE States A UE in RRC connected state can be in one of states – CELL_DCH, CELL_FACH, CELL_PCH and URA_PCH Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 75 (81) Ericsson Internal Admission Control Admission Control is invoked whenever new or additional dedicated resources are required; such as an access attempt, a soft handover request, or a radio bearer reconfiguration request In either of these cases, the Admission Control algorithm must confirm there are adequate system resources available to support this new request Examples of these resources include codes, power and channel elements In the case of an access attempt, the Admission Control algorithm may be invoked multiple times When a RRC Connection Request message is received on the RACH, the corresponding RRC Connection Setup Complete message typically instructs the UE to setup a dedicated SRB Regardless if the request is for CS, PS or simply a reselection, Admission Control must confirm resources are available to support the requested SRB In addition, the algorithm is invoked again once the RNC receives a RAB Assignment Request from the core network In the case of CS call, the SRB is reconfigured to include the AMR transport channels; and resources must be confirmed If the RAB Assignment Request is for PS Services, Admission Control must confirm that DCH or HS resources are available In the case of an ongoing DCH PS session, a radio bearer reconfiguration may be requested by the channel switching algorithm to support higher user throughput Since this reconfiguration would require additional codes, power, and channel elements, Admission Control would obviously be triggered Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 76 (81) Ericsson Internal Congestion Control Congestion Control monitors the dynamic utilization of specific cell resources and insures that overload conditions not occur If overload conditions occur, Congestion Control will immediately restrict Admission Control from granting additional resources In addition, Congestion Control will attempt to resolve the congestion by either down switching, or terminating existing users Once the congestion is corrected, the congestion resolution actions will cease, and Admission Control will be enabled Three types of overload are monitored as part of Congestion Control • • • UL overload measures the UL interference in a cell DL overload measured with the DL non-HSDPA transmitted carrier power Dl HSDPA overload measured with the available DL transmitted carrier power for HSDPA Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 77 (81) Ericsson Internal Cell Breathing The cell coverage shrinks as the loading increases, this is called cell breathing In the uplink, as more and more UE are served by a cell, each UE needs to transmit higher power to compensate for the uplink noise rise As a consequence, the UE with weaker link (UE at greater distance) may not have enough power to reach the NodeB – therefore a coverage shrinkage In the downlink, the NodeB also needs to transmit higher power as more UE are being served As a consequence UE with weaker link (greater distance) may not be reachable by the NodeB Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 78 (81) Ericsson Internal Radio Access Bearer The purpose of a Radio Access Bearer (RAB) is to provide a connection segment using the WCDMA Radio Access Network (WCDMA RAN) for support of a UMTS bearer service The WCDMA RAN can provide Radio Access Bearer connections with different characteristics in order to match requirements for different UMTS bearers Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 79 (81) Ericsson Internal HARQ The HARQ is the use of conventional ARQ along with an Error Correction technique called 'Soft Combining', which no longer discards the received bad data (with error) With the 'Soft Combining' data packets that are not properly decoded are not discarded anymore The received signal is stored in a 'buffer', and will be combined with next retransmission That is, two or more packets received, each one with insufficient SNR to allow individual decoding can be combined in such a way that the total signal can be decoded! Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 80 (81) Ericsson Internal Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 81 (81) Ericsson Internal ... 2016-08-30 UMTS OVERVIEW (81) Ericsson Internal 3G standardization organizations  Standardization organizations such as 3GPP, 3GPP2 were established WCDMA CDMA2000 3GPP 3G system 3GPP2 FDD/TDD... Rev: PA1 Date: 2016-08-30 UMTS OVERVIEW 24 (81) Ericsson Internal UMTS FDD Frame Structure Prep: Vikash Gupta Appr: Sukhpreet Singh Checked: Rev: PA1 Date: 2016-08-30 UMTS OVERVIEW 25 (81) Ericsson... Date: 2016-08-30 UMTS OVERVIEW 26 (81) Ericsson Internal Prep: Vikash Gupta Appr: Sukhpreet Singh Rev: PA1 Checked: Date: 2016-08-30 UMTS OVERVIEW 27 (81) Ericsson Internal UMTS Network Specifications