zte lte fdd physical layer procedure feature description

LTE FDD

Physical Layer Procedure Feature Description

Dong.Yuexin

矩形


ZTE Confidential Proprietary © 2011 ZTE Corporation. All rights reserved. I

LTE FDD Physical Layer Procedure Feature Description

Version Date Author Approved By Remarks

V1.0 2011-04-12 Tao Linan Not open to the Third Party

V2.0 2011-09-01 Tao Linan Not open to the Third Party

© 2011 ZTE Corporation. All rights reserved.

ZTE CONFIDENTIAL: This document contains proprietary information of ZTE and is not to be disclosed or used without the prior written permission of ZTE.

Due to update and improvement of ZTE products and technologies, information in this document is subjected to change without notice.


II © 2011 ZTE Corporation. All rights reserved. ZTE Confidential Proprietary

TABLE OF CONTENTS

1 Introduction ................................................................................................................ 1

2 Overview ..................................................................................................................... 1 2.1 Acquisition and Cell Search ......................................................................................... 1 2.2 Random Access ........................................................................................................... 1 2.3 Uplink Timing Control .................................................................................................. 2 2.4 Uplink Power Control ................................................................................................... 3

3 Technical Description ................................................................................................ 3 3.1 Acquisition and Cell Search ......................................................................................... 3 3.1.1 Cell Search Procedure ................................................................................................. 3 3.2 Random Access Procedure ......................................................................................... 5 3.2.1 Initialization .................................................................................................................. 5 3.2.2 Random Access Procedures ....................................................................................... 5 3.3 Uplink Timing Control .................................................................................................. 9 3.3.1 Initial Timing Adjustments .......................................................................................... 10 3.3.2 Transmission Timing Adjustments ............................................................................. 10 3.3.3 Maintenance of Uplink Time Alignment ..................................................................... 11 3.4 Power Allocation and Power Control ......................................................................... 11 3.4.1 Principle ..................................................................................................................... 11 3.4.2 UL Transmission Power for PUSCH .......................................................................... 12 3.4.3 Closed-loop Power Control for PUSCH Intra-cell ...................................................... 13 3.4.4 Power Control for PUSCH by ICIC ............................................................................ 14 3.4.5 UL Transmission Power for PUCCH ......................................................................... 14 3.4.6 Closed-loop Power Control for PUCCH ..................................................................... 15 3.4.7 UL Transmission Power for Sounding RS ................................................................. 15

4 Configuration of Parameters ................................................................................... 16 4.1 Acquisition and Cell Search Parameters ................................................................... 16 4.1.1 Acquisition and Cell Search Parameter List .............................................................. 16 4.1.2 Acquisition and Cell Search Parameter Configuration .............................................. 16 4.2 Random Access Parameters ..................................................................................... 16 4.2.1 Random Access Parameter List ................................................................................ 16 4.2.2 Random Access Parameter Configuration ................................................................ 17 4.3 Uplink Timing Control Parameters ............................................................................. 22 4.3.1 Uplink Timing Control Parameter List ........................................................................ 22 4.3.2 Uplink Timing Control Parameter Configuration ........................................................ 22 4.4 Uplink Power Control Parameters ............................................................................. 23 4.4.1 Uplink Power Control Parameter List ........................................................................ 23 4.4.2 Uplink Power Control Parameter Configuration......................................................... 23

5 Glossary .................................................................................................................... 26

FIGURES

Figure 1 Cell Search Procedure ................................................................................................... 4 Figure 2 Random Access Procedure ........................................................................................... 6 Figure 3 Random Access Preamble Format ................................................................................ 8


ZTE Confidential Proprietary © 2011 ZTE Corporation. All rights reserved. III

Figure 4 Timing Advance Command ......................................................................................... 10 Figure 5 UL Power Control of PUSCH ....................................................................................... 13

TABLES

Table 1 TPC Command for Accumulation Disabled Mode ....................................................... 14 Table 2 TPC Command for Accumulation Mode ...................................................................... 14


ZTE Confidential Proprietary © 2011 ZTE Corporation. All rights reserved. 1

1 Introduction This document provides a high-level description of physical layer procedures available in the ZTE LTE FDD products. The document also contains parameters, counter, alarm related to the physical layer procedures.

Acronyms, terms & definitions in this document can be found in Glossary.

2 Overview This chapter outlines the procedures necessary for a LTE terminal to be able to access an LTE network and transmit the data. These procedures are as follows:

• Acquisition and Cell Search;

• Random Access;

• Uplink Timing Control;

• Power Control;

2.1 Acquisition and Cell Search Before an LTE terminal can communicate with an LTE network, it has to do the followings:

• Find and acquire synchronization to a cell within the network.

• Receive and decode the information (also refer to as system information) needed to communicate with and operate properly within the cell.

• Once the system information has been correctly decoded, the terminal can access the cell by means of so-called random access procedure.

The first of these steps, often simply referred to as cell search, is explained in details in Section 3.1.

2.2 Random Access A LTE User Equipment (UE) can only be scheduled for uplink transmission when its uplink transmission timing is synchronized. The LTE Random Access Channel (RACH) plays a key role as an interface between non-synchronized UEs and the orthogonal transmission scheme of the LTE uplink radio access.


2 © 2011 ZTE Corporation. All rights reserved. ZTE Confidential Proprietary

In WCDMA, the RACH is primarily used for initial network access and short message transmission. LTE likewise uses the RACH for initial network access, but in LTE the RACH cannot carry any user data, which is exclusively sent on the Physical Uplink Shared Channel (PUSCH). Instead, the LTE RACH is used to achieve uplink time synchronization for a UE which either has not yet acquired, or has lost its uplink synchronization. Once uplink synchronization is achieved for a UE, the eNodeB can schedule orthogonal uplink transmission resources for it. Relevant scenarios in which the RACH is used are therefore:

1 A UE in RRC_CONNECTED state, but not uplink-synchronized, needs to send new uplink data or control information (e.g. an event-triggered measurement report);

2 A UE in RRC_CONNECTED state, but not uplink-synchronized, needs to receive new downlink data, and therefore to transmit corresponding ACK/NACK in the uplink;

3 A UE in RRC_CONNECTED state, handovers from its current serving cell to a target cell;

4 A transition from RRC_IDLE state to RRC_CONNECTED, for example for initial access or tracking area updates;

5 Recovering from radio link failure.

One additional exceptional case is that an uplink-synchronized UE is allowed to use the RACH to send a Scheduling Request (SR) if it does not have any other uplink resource allocated in which to send the SR. These roles require the LTE RACH to be designed for low latency, as well as good detection probability at low Signal-to-Noise (SNR) (for cell edge UEs undergoing handover) in order to guarantee similar coverage to that of the PUSCH and Physical Uplink Control Channel (PUCCH).

The related random access procedure and configurations are explained in Section 3.2 in details.

2.3 Uplink Timing Control A key feature of the uplink transmission scheme in LTE is that it is designed for orthogonal multiple-access in time and frequency domains between the different UEs.

Since SC-FDMA is deployed in uplink in LTE, uplink orthogonality has to be guaranteed by ensuring that the transmissions from different UEs in a cell are time-aligned at the receiver of the eNodeB. Only in this way can the intra-cell interference be avoided, both between UEs assigned to transmit in consecutive sub-frames and between UEs transmitting on adjacent sub-carriers.

Time alignment of the uplink transmissions is achieved by applying a timing advance at the UE transmitter, relative to the received downlink timing. The main role of this is to counteract differing propagation delays between different UEs and the details can be found in Section 3.3.

When the new RRC connection is established, MME selects an S-GW based on S-GW selection function and triggers the default bearer establishment associated with the UE. During the procedure, the eNodeB starts ciphering of user data over Uu interface.



2.4 Uplink Power Control Uplink power control is the method by which the transmit power for different uplink physical Channels and signals are controlled to ensure that they can be received at the cell site with an appropriate power.

Following topics are explained in Section 3.4:

• PUCCH power control;

• PUSCH power control;

• SRS power control;

The uplink demodulation reference signals are always transmitted together with PUSCH or PUCCH and are then transmitted with the same power as the corresponding physical Channels.

Fundamentally, uplink power control is a combination of an open-loop mechanism, implying that the terminal transmit power depends on estimations of the downlink path-loss, and a closed-loop mechanism, implying that the network can,directly control the terminal transmit power by means of explicit power control commands transmitted in the downlink.

3 Technical Description

3.1 Acquisition and Cell Search

3.1.1 Cell Search Procedure

Cell search procedures are applied in two ways in LTE:

• Initial synchronization: Performed when UE detects an LTE cell and decodes all the information required to register to it. This would be required, for example, when the UE is switched on, or when it has lost the connection to the serving cell.

• New cell identification: Performed when a UE is already connected to an LTE cell and is in the process of detecting a new neighboring cell. In this case, the UE reports to the serving cell measurement results related to the new cell, in preparation for handover. As illustrated in following Figure 1, if PCI is informed by eNodeB in measurement control message, there is no need for UE to detect PCI during handover procedure. This enables a fast handover procedure.



Figure 1 Cell Search Procedure

PSS Detection

Slot edge detectionPCI detection

SSS Detection

Radio Frame edge detectionPCI detection

CP length detectionTDD/FDD detection

Initial Synchronization

PBCH decodingSIB info acquisition

New Cell Identification

RS detectionRSRP/RSRQ acquisition

PCI informed during HO

Two physical synchronization signals are utilized in the synchronization procedure, which are broadcast in each cell: the Primary Synchronization Signal (PSS) and the Secondary Synchronization Signal (SSS). Downlink time and frequency synchronization are achieved, via detection of these two signals. At the same time, the following characteristics of the network are also determined: the physical-layer cell identity PCI, the cyclic prefix length, and the frame type, that is Frequency Division Duplex (FDD) or Time Division Duplex (TDD).

The cell search and synchronization procedure is summarized in Figure 1, which shows the information obtained by the UE at each stage. The PSS and SSS structure are specifically designed to facilitate this acquisition of information, and is detailed in 错误！

未找到引用源。.

As illustrated in Figure 1, the UE firstly detects the PSS via non-coherent detection. After the PSS is detected, the UE knows the slot edge, 5ms edge and part of PCI, except knowing the 10ms radio frame edge, CP length and frame type. Then after the 2nd step, SSS detection, the UE knows the 10ms radio frame edge, the complete PCI, the CP length and which frame type is used in this cell, FDD or TDD.

Because the frequency location of PSS and SSS are designed by 3GPP in the central six Resource Blocks (RBs), the frequency mapping of the synchronization signals is invariant independent of the system bandwidth (which can vary from 6 to 110 RBs); So the UE can synchronize to the LTE network without any priori knowledge of the allocated bandwidth, which can only be found after system information is decoded in PBCH.

And because PSS in one cell is the same in every sub-frame in which it is transmitted, while the two SSS transmissions in each radio frame change in an alternated manner, the UE is facilitated to find the 10 ms radio frame boundary.

Since the location of SSS sequence changes with the CP length, the CP length then can be blindly detected by coherent or non-coherent checking for the SSS at the two possible positions.

A physical-layer cell identity, PCI, (2)ID

(1)ID

cellID 3 NNN += is uniquely defined by a

number(1)IDN in the range of 0 to 167, representing the physical-layer cell-identity group,



and a number(2)IDN in the range of 0 to 2, representing the physical-layer identity within

the physical-layer cell-identity group. (2)IDN is determined by PSS detection and

(1)IDN is

determined by SSS detection.

After the detection of synchronization signals, in the case of the initial synchronization, the UE proceeds to decode the Physical Broadcast Channel (PBCH), and then obtain the system information. In the case of new cell identification, the UE does not need to decode the PBCH; it simply makes quality-level measurements based on the reference signals transmitted from the newly-detected cell and reports these to the serving cell.

3.2 Random Access Procedure

3.2.1 Initialization

Before the random access procedure, there are several necessary parameters for UE to acquire in system information broadcast messages, like RACH configuration and PRACH configuration in SIB2:

Prach-ConfigIndex: The available set of PRACH resources for the transmission of the Random Access Preamble are implicitly indicated;

PreambleInfo: The number of available preambles for the cell, and the groups of Random Access Preambles and the set of available Random Access Preambles in each group are defined in this IE explicitly; notice, there is a maximum number 64 of preamble signatures available in each LTE cell;

Ra-SupervisionInfo: The RA response window size, the Contention Resolution Timer and the maximum number of preamble transmission are defined here explicitly;

PowerRampingParameters: The power-ramping factor, powerRampingStep and the initial received target preamble power (preambleInitialReceivedTargetPower) are defined here explicitly;

MaxHARQ-Msg3Tx: The maximum number of Msg3 HARQ transmissions is defined;

3.2.2 Random Access Procedures

Two types of random access procedure are defined in LTE: allowing access to be either contention-based (implying an inherent risk of collision) or contention-free.

The contention-based random access procedure is suitable for all use-cases listed in Section 2.2. In this procedure, the random access preamble signatures are broadcast in SIB, and are randomly chosen by the UE. So it is possible that more than one UE simultaneously choose and transmit the same preamble signature, which may lead to a subsequent contention resolution process.

The contention-free random access procedure is suitable for the cases of new downlink data arrival and handover in Section 2.2. The contention can be avoided by the eNodeB via allocating a dedicated signature to a UE. This is faster than contention-based access, which is particularly important for some time-critical cases, like handover.



The two procedures are detailed in the following sections.

Figure 2 Random Access Procedure

UE eNodeB

Message1: RA Preamble

Message2: RAR (TA Command, UL Grant, Temp-CRNTI)

Message3: L2/L3 Message

Message4: message for early contention resolution

3.2.2.1 Random Access Message 1

6 Step 1: As described above, when UE have collected all the needed information defined in Section 3.2.1, and when it’s going to initiate a random access, it shall firstly determine the next available sub-frame containing PRACH permitted by the restrictions given by the PRACH Configuration Index, the PRACH Mask Index and physical layer timing requirements, acquired in SIB as indicated in section 3.2.1.

7 Step 2: After the PRACH resource is determined, UE shall select one preamble as follows:

• In case of contention based random access, it shall randomly select one preamble from the groups of Random Access Preambles in SIB2. UE shall select a preamble from the Random Access Preambles group B, if following conditions fulfilled:

− Random Access Preambles group B exists;

− The potential message size is greater than the Message Size for Group A;

− The path loss is less than the threshold for group B

i Else, it shall select a preamble from the Random Access Preambles group A.

• In case of contention free based random access, a UE specific preamble will be configured to UE before the random access procedure, like handover preparation stage during handover procedure, then it shall definitely take this preamble to initiate the random access procedure.



8 Step 3: After the PRACH preamble is chosen, it shall be sent with dedicated power setting. The initial preamble transmission power setting shall be based on open-loop estimation with full compensation for the path-loss by UE. Because the eNodeB has to detect several simultaneous preamble transmissions in the same time-frequency PRACH resource, it is necessary that the received power of the preambles from different UE is independent of the path-loss. The averaging measurement of downlink Reference Signal Received Power (RSRP) is used by the UE to estimate the path-loss.

ii The eNodeB may also configure an additional power offset, depending for example on the desired received Signal to Interference plus Noise Ratio (SINR), the measured uplink interference and noise level in the time-frequency slots allocated to RACH preambles, and possibly also on the preamble format.

iii The detailed transmission power of PRACH preamble by UE shall be set as follows:

iv

ngSteppowerRampiCOUNTERONTRANSMISSIPREAMBLE

PREAMBLEDELTAetPowerceivedTitialpreambleIn

POWERTARGETRECEIVEDPREAMBLE

*)1__(

_argRe

___

−++

=

v Where,

• PREAMBLE_RECEIVED_TARGET_POWER is UE transmission power for preamble;

• PreambleInitialReceivedTargetPower is eNodeB expected received power for preamble;

• DELTA_PREAMBLE is a power offset for different preamble format;

• PREAMBLE_TRANSMISSION_COUNTER is counter in UE to count the transmission times for preamble;

• PreambleRampingStep is a high layer configured power ramping up parameter for retransmission of preamble;

vi One basic concept, RA_RNTI, can then be defined in this step as following equation, and will be used later during message 2 processing:

vii idfidtRNTIRA _*10_1_ ++= .

viii Where, t_id is the slot number in which PRACH preamble is transmitted; f_id is the frequency resource index on which PRACH preamble is transmitted. For FDD, only one frequency resource is defined in one slot.

ix To facilitate the handling of possible retransmissions of preamble, a counter, PREAMBLE_TRANSMISSION_COUNTER, is used inside UE to count the



current transmission occasions. For the initial preamble transmission, the counter is set to 1, and if no Random Access Response (Message 2) received inside the RA Response window, the UE shall increment PREAMBLE_TRANSMISSION_COUNTER by 1 and delay the subsequent Random Access transmission by a random back-off time, and then repeat the Random Access Message 1 procedure described above.


At the time slot for random access opportunity, eNodeB shall detect the preamble sequence, and check whether any preamble is higher than threshold, and then grant UEs with these preamble sequences for access.

For the grant, eNodeB shall send the random access message 2, named Random Access Response (RAR) on the Physical Downlink Shared Channel (PDSCH), which is addressed with the RA-RNTI, identifying the time-frequency slot where the preamble was detected. However, in case that several UEs choose the same signature in the same preamble time-frequency resource, all of them would receive the RAR in a collision.

Back-off indicator and RAP Id (Random Access Preamble Id) are included in MAC Control Elements of RAR message. At the same time, the UL Grant for later UL message 3 and UL timing advance command are indicated to UE in RAR message.

A time window is defined in 3GPP, within which RAR message shall be received by UE. The start and end of the time window are configured by the eNodeB and broadcast as part of the cell-specific system information. As allowed by the specifications, the earliest sub-frame shall be no earlier than 3 ms after the end of the preamble sub-frame, as illustrated in the following Figure 3. And the RA Response Window size is broadcast as described in section 3.2.1.

Figure 3 Random Access Preamble Format

PRACH RAR ……

RA Response Window


The Random Access Message 3 is used to transmit the L2/L3 message, like RRC Connection Request message in initial access procedure, or RRC Connection Reconfiguration Complete message addressed by C-RNTI in handover procedure. The Random Access Message 3 is the 1st scheduled UL message on PUSCH in the way of HARQ scheme.

Once a RAR message is detected in sub-frame n, the UE shall, according to the information in the response, transmit Random Access Message 3, an UL-SCH transport

block in the first sub-frame n+k1, 61 ≥k , if the UL delay field in the UL Grant field of RAR message is set to zero. The UE shall postpone the PUSCH transmission to the next available UL sub-frame if the field is set to 1.



For a contention-based random access procedure, UE shall include a C-RNTI MAC control element in the MAC header of the message 3, which is set to the received Temporary C-RNTI. And in RRC message body of Message 3, an UE Id shall be included, either the C-RNTI if the UE already has one (RRC_CONNECTED UEs) or the (unique) 48-bit UE identity.

If more than one UE have sent the same preamble in the same RA-RNTI, a collision occurs. The colliding UEs will receive the same Temporary C-RNTI through the RAR message and will also collide in the same uplink time-frequency resources when transmitting their L2/L3 message. This may result in the fact that no colliding UE can be decoded in eNodeB because of interference, and the UEs restart the random access procedure after reaching the maximum number of HARQ retransmissions. However, if one UE is successfully decoded by eNodeB, the contention remains unresolved for the other UEs. The following downlink message 4 allows a quick resolution of this contention.


The Random Access Message 4 is a message with HARQ transmission. The message is addressed with C-RNTI or Temporary C-RNTI. If a Temporary C-RNTI is used for address, an explicit UE identity shall be included in L2/L3 message body.

As described in section 3.2.2.3, message 4 can be used for a quick resolution of contention. An UE Contention Resolution Identity MAC Control Element shall be included in the MAC header of Message 4, which contains the UL CCCH SDU and unique for UE. So, when UEs, who thought themselves are granted by RAR message and send the message 3, decode the message 4, and check the UE Contention Resolution Identity, they know whether they are correctly contention resolved or not.

In case of a collision followed by successful decoding of the L2/L3 message, the HARQ feedback is transmitted only by the UE which detects its own UE identity (or C-RNTI); other UEs understand there was a collision, transmit no HARQ feedback, and can quickly exit the current random access procedure and start another one. The UE’s behavior upon reception of the contention resolution message therefore has three possibilities [5]:

• The UE correctly decodes the message and detects its own identity, then it sends back a positive acknowledgement, ‘ACK’.

• The UE correctly decodes the message and discovers that it contains another UE’s identity (contention resolution), then it sends nothing back (Discontinuous Transmission, ‘DTX’).

• The UE fails to decode the message or misses the DL grant, then it sends nothing back (‘DTX’).

3.3 Uplink Timing Control

Transmission of the uplink radio frame number i from the UE shall start soffsetTA TA )( TNN ×+ seconds before the start of the corresponding downlink radio frame

at the UE, where 0 ≤ TAN ≤ 20512, 0offsetTA =N for LTE FDD.



The UE shall adjust its uplink transmission timing for PUCCH/PUSCH/SRS, after a valid timing advance command is received. The timing adjustment accuracy of timing

advance command is 16 sT .

3.3.1 Initial Timing Adjustments

After an UE has finished the cell search and DL timing acquisition as detailed in section 3.1, it has synchronized its receiver to the downlink transmissions received from the eNodeB, and the initial timing advance is set by means of the random access procedure as described in detail in section 3.2.

UE transmits a random access preamble, and the eNodeB can estimate the uplink timing and respond with an 11-bit initial timing advance command included in the Random Access Response (RAR) message, in which an 11-bit timing advance command, TA, indicates TAN values by index values of TA = 0, 1, 2, ..., 1282, where

an amount of the time alignment is given by TAN = TA ×16.

3.3.2 Transmission Timing Adjustments

During the normal UL transmission, a timing advance command in 6-bit TA is used, and indicates the adjustment of current TAN value. TA means the adjustment from TA,oldN

to newTA,N , by index values of TA = 0, 1, 2,..., 63, which means newTA,N = TA,oldN +

(TA −31)×16. From the equation above, the TA value, which could be a positive or a negative amount, indicates advancing or delaying the uplink transmission timing by a given amount respectively.

If UE receives a timing advance command on sub-frame N, it shall apply the corresponding adjustment of the UL timing from the beginning of sub-frame n+6, as illustrated in Figure 4.

Figure 4 Timing Advance Command

Timing Advance N+1 N+2 N+3 N+4 N+5 N+6

Timing Advance N+1 N+2 N+3 N+4 N+5 N+6

N+1 N+2 N+3 N+4 N+5

N+1 N+2 N+3 N+4 N+5 New ULtiming

eNB DL Tx

UE DL Rx

UE UL Tx

eNB UL Rx

New ULtiming

Transmission delay

Transmission delay

At the sub-frame N when the timing adjustment take effects, the UE’s uplink transmissions in sub-frame N and sub-frame N+1 may be overlapped; in this case, the whole sub-frame N shall be transmitted, without the overlapped part of sub-frame N+1.



3.3.3 Maintenance of Uplink Time Alignment

The eNodeB shall manage and maintain the timeAlignmentTimerCommon and timeAlignmentTimerDedicated. TimeAlignmentTimerCommon is broadcast in SIB2; and radioResourceConfigDedicated is included in RRC Connection Setup or RRC Connection Reconfiguration message.

The UE shall manage the timeAlignmentTimer according to received timeAlignmentTimerCommon and radioResourceConfigDedicated.

3.4 Power Allocation and Power Control

3.4.1 Principle

There is only power allocation in DL in LTE, and power control in UL.

9 The principle of DL power allocation is as follows:

The DL power allocation in eNodeB is determined by per resource element.

The transmission power of cell-specific RS, EPRE (Energy Per Resource Element), is broadcast in SIB message, and is constant across the whole system bandwidth.

The power ratio of PDSCH EPRE to cell-specific RS EPRE among PDSCH REs is denoted by either Aρ or Bρ according to the OFDM symbol index. In OFDM symbols where there are cell-specific RS located, the ratio is denoted by Bρ ; and in OFDM symbols where there is no cell-specific RS located, the ratio is denoted by Aρ .

In high layer configuration (RRC reconfiguration message), there are two parameters: PA and PB. The power ratio Aρ and Bρ can be worked out by PA and PB.

In high order modulation, like 16QAM and 64QAM, and in case of spatial multiplexing with more than one layer or for PDSCH transmissions associated with the multi-user MIMO transmission scheme, because the power ratio impact the demodulation of constellation point in one quadrant, UE have to take Aρ into consideration. Aρ is

equal to )2(log10 10offset-power ++ APδ [dB], when the UE receives a PDSCH data transmission using pre-coding for transmit diversity with 4 cell-specific antenna ports; and is equal to AP+offset-powerδ [dB] in other cases.

PB is defined as the ratio of AB ρρ / , and is a cell-specific parameter.

The principle of uplink power control in LTE is quite different from WCDMA one:

• WCDMA is a code division and multiplexing system, which requires that the received power of different UEs with different codes in NodeB keeps nearly the same; the power control in WCDMA then aims at adjusting the received power in NodeB, which is intra-cell power control.



• LTE deploys the OFDM technology, with which no interference between different UEs exists inside cell, if the inter-carrier-interference could be omitted. So in a single-cell environment, it’s better for UE to transmit UL data as higher as possible, but not necessary higher than power needed by the highest MCS. So the UL power control in LTE aims at:

− Inter-cell interference co-ordination or cancellation.

− Fit the transmitted power to the MCS and scheduled PRB.

3.4.2 UL Transmission Power for PUSCH

The setting of the UE Transmit power PUSCHP for the physical uplink shared Channel (PUSCH) transmission in sub-frame i is defined by [4]

)}()()()())((log10,min{)( TFO_PUSCHPUSCH10CMAXPUSCH ifiPLjjPiMPiP +∆+⋅++= α [dBm]

Where,

• PCMAX is maximum transmission power of UE;

• MPUSCH is a adjustment for PRB number;

• )(O_PUSCH jP is a parameter composed of the sum of a cell specific nominal

component )( PUSCHO_NOMINAL_ jP provided from higher layers and a UE specific

component )(O_UE_PUSCH jP provided by higher layers;

• Alpha α is a partial path loss compensation parameter;

• PL is path loss estimated by UE;

• TF∆ is adjustment for MCS and TBS;

• F(i) is closed-loop power control parameter indicated by eNodeB.

There are open-loop and closed-loop power control in PUSCH power control scheme, as illustrated in Figure 5. AMC is Adaptive Modulation and Coding module, which works for link adaptation; ICIC is inter-cell interference co-ordination module; OLPC is open-loop power control; CLPC is closed-loop power control; SINRSRS is SINR of Sounding RS measured and filtered in physical layer.

Power control module receives PRB and MCS grant from AMC module, and OI indicator from ICIC module, and SINRSRS from physical layer report. And after the work of power control algorithm, PO_PUSCH is output to open-loop power control, and f(i) is output to closed-loop power control. And the initial power control parameters setting, like PO_PUSCH , Alpha, etc, are configured by RRC protocol.



Figure 5 UL Power Control of PUSCH

Power controlAMC ICICOIPRB,MCS

Popusch F(i)

OLPC CLPC

RRC

Popusch, Alpha

PHY report

SINRSRS

3.4.3 Closed-loop Power Control for PUSCH Intra-cell

Power Header Room Report

The UE power headroom PH valid for sub-frame i is defined by [4]

{ })()()()())((log10)( TFO_PUSCHPUSCH10CMAX ifiPLjjPiMPiPH +∆+⋅++−= α

[dB]

Where, CMAXP , )(PUSCH iM , )(O_PUSCH jP , )( jα , PL, )(TF i∆ and )(if are described in section 3.4.2.

The power headroom shall be rounded to the closest value in the range [40; -23] dB with steps of 1 dB and is delivered by the physical layer to higher layers for power control and scheduling.

Closed-Loop Power Control for PUSCH

The SRSSINR , which is reported from Physical Layer as the SINR on Sounding RS with some filtering and combination is checked as following equation:

_ PUSCH SRSSINR SINR Target SINR∆ = −

The SINR_TargetPUSCH is the target SINR for PUSCH, provided by out-loop power control module.



In case of accumulation disabled mode, the TPC_COMMAND is detailed as Table 1 :

Table 1 TPC Command for Accumulation Disabled Mode

SINR∆ >= 3dB

SINR∆ >= 0dB

SINR∆ > -3dB

Others

TPC_COMMAND 4 1 -1 -4

In case of accumulation mode, the TPC_COMMAND is detailed as Table 2 :

Table 2 TPC Command for Accumulation Mode

SINR∆ >= 3dB SINR∆ >=

1dB SINR∆ >

-1dB SINR∆

<= -1dB DCI format0/3

DCI format 3A

TPC_COMMAND 3 1 1 0 -1

It should be noted that if the Power Head Room Report from UE equals 0 and TPC_COMMAND is bigger than 0, then:

• If accumulation mode enabled, the TPC_COMMAND equals 0;

• If accumulation mode disabled, TPC_COMMAND equals -1.

3.4.4 Power Control for PUSCH by ICIC

The power control triggered by ICIC is depicted in details in section 3.4.2 of [7].

3.4.5 UL Transmission Power for PUCCH

The setting of the UE Transmit power PUCCHP for the physical uplink control Channel (PUCCH) transmission in sub-frame i is defined by [4]

( ) ( ) ( ) ( ){ }igFnnhPLPPiP HARQCQI +∆+++= F_PUCCH0_PUCCHCMAXPUCCH ,,min [dBm]

Where,


• O_PUCCHP is a parameter composed of the sum of a cell specific parameter

PUCCH O_NOMINAL_P provided by higher layers and a UE specific component

O_UE_PUCCHP provided by higher layers;

• PL is path loss estimated by UE;



• ( )nh is a PUCCH format dependent value, where CQIn corresponds to the number

information bits for the channel quality information and HARQn is the number of

HARQ bits.

• PUCCHF _∆ is adjustment for PUCCH format 1a;

• g(i) is closed-loop power control parameter indicated by eNodeB.

The power control of PUCCH is different from that of PUSCH:

• Power control of PUSCH is a power spectrum density (PSD) based power control, and is a fractional path-loss compensational one, with Alpha equal or lower than 1.

• Power control of PUCCH is a power based power control, and is a full path-loss compensational one, with Alpha equaling one.

The reason is that the power of PUSCH is dependent from number of PRB, so it’s PSD based; and fractional path-loss compensation factor Alpha is used to control the interference to neighboring cells.

From the equation above, there are also open-loop power control (OLPC) and closed-power control (CLPC) for PUCCH. PO_PUCCH is output to OLPC, and g(i) is output to CLPC. The CLPC of PUCCH takes SINR of DMRS of PUCCH.

3.4.6 Closed-loop Power Control for PUCCH

The procedure of closed-loop power control is the same as that of PUSCH, except that the SINRSRS should be replaced by SINRPUCCH_DMRS, which is the estimated SINR based on DMRS of PUCCH:

__ PUCCH PUCCH DMRSSINR SINR Target SINR∆ = −

Notice that: the SINR target of PUCCH is independent of that of PUSCH.

3.4.7 UL Transmission Power for Sounding RS

The setting of the UE Transmit power SRSP for the Sounding Reference Symbol transmitted on sub-frame i is defined by [4]

)}()()()(log10,min{)( O_PUSCHSRS10SRS_OFFSETCMAXSRS ifPLjjPMPPiP +⋅+++= α [dBm]

Where,




• PSRS_OFFSET is a 4-bit UE specific parameter semi-statically configured by higher layers;

• MSRS is a adjustment for PRB number used by Sounding RS;

• )(O_PUSCH jP , α , PL and f(i) are the same as that in PUSCH power control;z

4 Configuration of Parameters

4.1 Acquisition and Cell Search Parameters

4.1.1 Acquisition and Cell Search Parameter List Abbreviated name Parameter name

wPhyCellId Physical Cell ID

4.1.2 Acquisition and Cell Search Parameter Configuration

4.1.2.1 Physical Cell ID

Parameter name Physical Cell ID

Abbrevatied name wPhyCellId

Description

This parameter is used to identify a cell. There are 504 unique physical-layer cell identities. The physical-layer cell identities are grouped into 168 unique physical-layer cell-identity groups, each group containing three unique identities. The grouping is such that each physical-layer cell identity is part of one and only one physical-layer cell-identity group. And the physical cell identities are space multiplexing and programmed by network programming people.

Range and Step (0,1,…,503) Unit N/A Default Value None

4.2 Random Access Parameters

4.2.1 Random Access Parameter List Abbreviated name Parameter name



Abbreviated name Parameter name

byPrachConfig PRACH Configuration Index

byPrachFreqOffset Initial RB Number for Random Access Preambles

byCellHighSpdAtt Cell high-speed attribute

wLogRtSeqStNum Logical root sequence start number used to generate PRACH preamble

byNcs Ncs used to generate PRACH preamble

byNumRAPreambles Number of Non-dedicated Random Access Preambles

bySizeRAGroupA Size of Random Access Preambles Group A

byPrachPwrStep Power Ramping Step for PRACH

byPreambleTxMax Maximum Times for Preamble Transmission

byPreInitPwr Initial power for preamble of PRACH

wSelPreGrpThresh Threshold of Selecting Preamble Group

byMesPowOffsetGroB Message Power Offset for Group B

byRARspWinSize TTI Window Size for PRACH Response

byMACContResTimer MAC Contention Resolution Timer

byMaxHARQMsg3Tx Max Number of Message3 HARQ Transmissions

4.2.2 Random Access Parameter Configuration

4.2.2.1 PRACH Configuration Index

Parameter name PRACH Configuration Index

Abbrevatied name byPrachConfig

Description

This parameter indicates the frame number and subframe number configuration, via different configuration, different opportunity used to transmit PRACH is also configured. In fact, This parameter gives the access opportunity for PRACH. The larger the number of frame and subframe used to transmit PRACH is, the more the access opportunity is.

Range and Step (0, …, 63) Unit N/A



4.2.2.2 Initial RB Number for Random Access Preambles

Parameter name Initial RB Number for Random Access Preambles

Abbrevatied name byPrachFreqOffset

Description This parameter is used to determine the frequency position used for PRACH. The PRACH uses 6 RB, from 0 to N_RB^UL-6.

Range and Step (0, …, 94) Unit N/A Default Value 0

4.2.2.3 Cell high-speed attribute

Parameter name Cell high-speed attribute

Abbrevatied name byCellHighSpdAtt

Description

This parameter indicates whether the cell is high-speed. If cell high-speed attribute is high-speed, The cyclic shift method to generate PRACH preamble sequence is different between high-speed cell and non high-speed cell. In high-speed cell, cyclic shift is restricted. In non high-speed cell, cyclic shift is not restricted.

Range and Step (non high-speed, high-speed) Unit N/A Default Value Non high-speed

4.2.2.4 Logical root sequence start number used to generate PRACH preamble

Parameter name Logical root sequence start number used to generate PRACH preamble

Abbrevatied name wLogRtSeqStNum

Description

This parameter indicates the logical root sequence start number used to generate PRACH preamble. There are 64 preambles available in each cell. The set of 64 preamble sequences in a cell is found by including first, in the order of increasing cyclic shift, all the available cyclic shifts of a root Zadoff-Chu sequence with the logical index RACH_ROOT_SEQUENCE, where RACH_ROOT_SEQUENCE is broadcasted as part of the System Information. Additional preamble sequences, in case 64 preambles cannot be generated from a single root Zadoff-Chu sequence, are obtained from the root sequences with the consecutive logical indexes until all the 64 sequences are found.

Range and Step (0, ..., 837) Unit N/A Default Value 0



4.2.2.5 Ncs used to generate PRACH preamble

Parameter name Ncs used to generate PRACH preamble

Abbrevatied name byNcs

Description

This parameter is used to determine the shift number of cyclic shift. There are 64 preambles available in each cell. The set of 64 preamble sequences in a cell is found by including first, in the order of increasing cyclic shift, all the available cyclic shifts (correlative to Ncs) of a root Zadoff-Chu sequence with the logical index RACH_ROOT_SEQUENCE, where RACH_ROOT_SEQUENCE is broadcasted as part of the System Information. Additional preamble sequences, in case 64 preambles cannot be generated from a single root Zadoff-Chu sequence, are obtained from the root sequences with the consecutive logical indexes until all the 64 sequences are found.

Range and Step (0, ..., 10) Unit N/A Default Value 6

4.2.2.6 Number of Non-dedicated Random Access Preambles

Parameter name Number of Non-dedicated Random Access Preambles

Abbrevatied name byNumRAPreambles

Description This parameter defines the number of contention based random access preambles.

Range and Step (4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64) Unit N/A Default Value 64

4.2.2.7 Size of Random Access Preambles Group A

Parameter name Size of Random Access Preambles Group A

Abbrevatied name bySizeRAGroupA

Description This parameter defines the number of Random Access preambles in Group A.

Range and Step (4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60) Unit N/A Default Value 60

4.2.2.8 Power Ramping Step for PRACH

Parameter name Power Ramping Setp for PRACH



Parameter name Power Ramping Setp for PRACH

Abbrevatied name byPrachPwrStep

Description

If no Random Access Response is received by UE after UE transmitted Random Access Preamble, UE will increase transmit power for PRACH by Power step and retry to transmit Random Access Preamble until Preamble_Transmission_Counter is equal to Max_retransmit_number_for_prach.

Range and Step (0, 2, 4, 6) Unit N/A Default Value 2

4.2.2.9 Maximum Times for Preamble Transmission

Parameter name Maximum Times for Preamble Transmission

Abbrevatied name byPreambleTxMax

Description

If no Random Access Response is received by UE after UE transmitted Random Access Preamble, UE will increase transmit power for PRACH by Power step and retry to transmit Random Access Preamble until Preamble_Transmission_Counter is equal to Max_retransmit_number_for_prach.

Range and Step (3, 4, 5, 6, 7, 8, 10, 20, 50, 100, 200) Unit N/A Default Value 6

4.2.2.10 Initial Power for Preamble of PRACH

Parameter name Initial Power of Preamble of PRACH

Abbrevatied name byPreInitPwr

Description This parameter indicates initial power for preamble of PRACH. It is that the first transmit power.

Range and Step (-120, …, -90) step 2 Unit dBm Default Value -104

4.2.2.11 Threshold of Selecting Preamble Group

Parameter name Threshold of Selecting Preamble Group

Abbrevatied name wSelPreGrpThresh

Description Based on This parameter of message3 size, UE determines to select the Random Access Preambles group A or group B.



Parameter name Threshold of Selecting Preamble Group

Range and Step (56, 144, 208, 256) Unit N/A Default Value 144

4.2.2.12 Message Power Offset for Group B

Parameter name Message Power Offset for Group B

Abbrevatied name byMsgPowOffsetGroB

Description This parameter is a power control margin for message 3 transmission configured by the eNB and is used to select the Random Access Preambles group A or group B.

Range and Step (-Infinity, 0, 5, 8, 10, 12, 15, 18) Unit dB Default Value 0

4.2.2.13 TTI Window Size for PRACH Response

Parameter name TTI Window Size for PRACH Response

Abbrevatied name byRARspWinSize

Description

Once the Random Access Preamble is transmitted, the UE shall monitor the PDCCH in the TTI window [RA_WINDOW_BEGIN - RA_WINDOW_END] for Random Access Response(s). This parameter indicates the monitor window size.

Range and Step (2, 3, 4, 5, 6, 7, 8, 10) Unit ms Default Value 5

4.2.2.14 MAC Contention Resolution Timer

Parameter name MAC Contention Resolution Timer

Abbrevatied name byMACContResTimer

Description

In the random access procedure, once the uplink message containing the C-RNTI MAC control element or the uplink message including CCCH is transmitted, MAC Contention Resolution Timer will be started. If MAC Contention Resolution Timer is running, UE will detect PDCCH and wait for the response from network and determine whether it is allowed to access network. If the MAC Contention Resolution Timer expires, UE considers this Contention Resolution not successful.

Range and Step (8, 16, 24, 32, 40, 48, 56, 64)




Unit N/A Default Value 32

4.2.2.15 Max Number of Message3 HARQ Transmissions


Abbrevatied name byMaxHARQMsg3Tx

Description In the random access procedure, the max number of messages 3 HARQ transmissions.

Range and Step (1, …, 8) Unit N/A Default Value 3

4.3 Uplink Timing Control Parameters

4.3.1 Uplink Timing Control Parameter List Abbreviated name Parameter name

byTimeAlignTimer Time Alignment Timer

4.3.2 Uplink Timing Control Parameter Configuration

4.3.2.1 Time Alignment Timer

Parameter name Time Alignment Timer

Abbrevatied name byTimeAlignTimer

Description

Specifies the number of consecutive subframe(s) the UE should consider itself as UL synchronized. When non UL synchronized, the UE shall use the Random Access procedure to request a Time Alignment Command prior to any UL transmission

Range and Step (500, 750, 1280, 1920, 2560, 5120, 10240, infinity) Unit subfrmae Default Value 500



4.4 Uplink Power Control Parameters

4.4.1 Uplink Power Control Parameter List Abbreviated name Parameter name

byPoNominalPusch0 P0 Nominal of PUSCH for Semi-Persistent Schedule

byPoNominalPusch1 P0 Nominal of PUSCH for Dynamic Schedule

byAlfa Alfa for Path Loss byPoNominalPucch P0 Nominal of PUCCH

bydtaPoPucchF1 Delta Power Offset for PUCCH Format 1

bydtaPoPucchF1b Delta Power Offset for PUCCH Format 1b

bydtaPoPucchF2 Delta Power Offset for PUCCH Format 2

bydtaPoPucchF2a Delta Power Offset for PUCCH Format 2a

bydtaPoPucchF2b Delta Power Offset for PUCCH Format 2b

bydtaPrmbMsg3 PRACH Message 3 Power Offset byFilterCoeffRsrp Filter Coefficient for RSRP

4.4.2 Uplink Power Control Parameter Configuration

4.4.2.1 P0 Nominal of PUSCH for Semi-Persistent Schedule

Parameter name P0 Nominal of PUSCH for Semi-Persistent Schedule

Abbrevatied name byPoNominalPusch0

Description

This parameter indicates the cell specific nominal power for PUSCH (re)transmissions corresponding to a semi-persistent grant. This parameter is used to calculate the transmit power of PUSCH, and embodies the power difference among cells.

Range and Step (-126, …, 24) Unit dBm Default Value 0

4.4.2.2 P0 Nominal of PUSCH for Dynamic Schedule

Parameter name P0 Nominal of PUSCH for Dynamic Schedule

Abbrevatied name byPoNominalPusch1

Description This parameter indicates the cell specific nominal power for PUSCH (re)transmissions corresponding to a dynamic



Parameter name P0 Nominal of PUSCH for Dynamic Schedule

scheduled grant. This parameter is used to calculate the transmit power of PUSCH, and embodies the power difference among cells.

Range and Step (-126, …, 24) Unit dBm Default Value 0

4.4.2.3 Alfa for Path Loss

Parameter name Alfa for Path Loss

Abbrevatied name byAlfa

Description This parameter is used to calculate the transmit power of PUSCH and is used to compensate the cell path loss corresponding to a semi-persistent grant and a dynamic scheduled grant. This parameter is a cell specific parameter.

Range and Step (0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0) Unit N/A Default Value 1.0

4.4.2.4 P0 Nominal of PUCCH

Parameter name P0 Nominal of PUCCH

Abbrevatied name byPoNominalPucch

Description This parameter indicates the cell specific nominal power for PUCCH. And it is used to calculate the transmit power for PUCCH and embodies the power difference among cells.

Range and Step (-127, …, -96) Unit dBm Default Value -100

4.4.2.5 Delta Power Offset for PUCCH Format 1

Parameter name Delta Power Offset for PUCCH Format 1

Abbrevatied name bydtaPoPucchF1

Description This parameter indicates the power offset for different PUCCH Format 1 with PUCCH Format 1a.

Range and Step (-2, 0, 2) Unit dB Default Value 0



4.4.2.6 Delta Power Offset for PUCCH Format 1b

Parameter name Delta Power Offset for PUCCH Format 1b

Abbrevatied name bydtaPoPucchF1b

Description This parameter indicates the power offset for different PUCCH Format 1b with PUCCH Format 1a.

Range and Step (1, 3, 5) Unit dB Default Value 1

4.4.2.7 Delta Power Offset for PUCCH Format 2

Parameter name Delta Power Offset for PUCCH Format 2

Abbrevatied name bydtaPoPucchF2

Description This parameter indicates the power offset for different PUCCH Format 2 with PUCCH Format 1a.

Range and Step (-2, 0, 1, 2) Unit dB Default Value 0

4.4.2.8 Delta Power Offset for PUCCH Format 2a

Parameter name Delta Power Offset for PUCCH Format 2a

Abbrevatied name bydtaPoPucchF2a

Description This parameter indicates the power offset for different PUCCH Format 2a with PUCCH Format 1a.


4.4.2.9 Delta Power Offset for PUCCH Format 2b

Parameter name Delta Power Offset for PUCCH Format 2b

Abbrevatied name bydtaPoPucchF2b

Description This parameter indicates the power offset for different PUCCH Format 2b with PUCCH Format 1a.




4.4.2.10 PRACH Message 3 Power Offset

Parameter name PRACH Message 3 Power Offset

Abbrevatied name bydtaPrmbMsg3

Description This parameter is a message-based offset used to compensate the power offset for different PREACH message format and is a cell specific parameter.

Range and Step (-2, …, 12) step 2 Unit dB Default Value 0

4.4.2.11 Filter Coefficient for RSRP

Parameter name Filter Coefficient for RSRP

Abbrevatied name byFilterCoeffRsrp

Description This parameter indicates the RSRP measurement filtering coefficient for layer 3.

Range and Step (0,1,2,3,4,5,6,7,8,9,11,13,15,17,19) Unit N/A Default Value 4

5 Glossary 3GPP 3rd Generation Partnership Project

A

AMC Adaptive Modulation and Coding

B

C

CLPC Closed Loop Power Control

CP Cyclic Prefix

CQI Channel Quality Indicator



D

DMRS DeModulation Reference Signal

DTX Discontinuous Transmission

E

EPRE Energy per Resource Element

F

FDD Frequency Division Duplex

G

H

HO Handover

I

ICIC Inter Cell Interference Coordination

L

LTE Long Term Evolution

M

MCS Modulation and Coding Scheme

MME Mobility Management Entity

N

O



OFDM Orthogonal Frequency Division Multiplexing

OI Overload Indication

OLPC Open Loop Power Control

P

PBCH Physical Broadcast Channel

PCI Physical Cell ID

PDSCH Physical Downlink Shared Channel

PRACH Physical Random Access Channel

PRB Physical Resource Block

PSD Power Spectrum Density

PSS Primary Synchronization Signal

PUCCH Physical Uplink Control Channel

PUSCH Physical Uplink Shared Channel

Q

R

RA Random Access

RACH Random Access Channel

RAR Random Access Response

RB Resource Block

RRC Radio Resource Control

RS Reference Signal

RSRP Reference Signal Received Power

RSRQ Reference Signal Received Quality

S



SC-FDMA Single Carrier – Frequency Division Multiplexing Access

S-GW Serving Gateway

SIB System Information Block

SINR Signal to Interference plus Noise Ratio

SNR Signal-to-Noise Ratio

SR Scheduling Request

SRS Sounding Reference Signal

SSS Secondary Synchronization Signal

T

TA Timing Advance

TDD Time Division Dulplex

TPC Transmit Power Control

U

UE User Equipment

V

X

Y

Z

zte lte fdd physical layer procedure feature description

Documents

zte corporation

proprietary information

cell search procedure

uplink power control

uplink timing control

improvement of zte products

technical description

power allocation