PBCH PCFICH PHICHPDCCH PMCHPDSCH PUSCH PUCCH PRACH

DL-SCH DCI HICFI MCHBCHPCH RACHUCIUL-SCH

DTCH CCCH DCCHBCCHPCCH CCCH DCCH MCCH MTCHDTCH

TM TM TM UM AM UM AM

Integrity

CipheringCiphering optional

ROHC

RRC

AM

Integrity

Ciphering

UMUM AM

Ciphering optional

ROHC

TM

SRB0 SRB1 SRB2 SRB0 SRB1 SRB2

RRC

SM GMM MM IP SM GMM MMUDP TCP UDPTCP

PHY

MAC

RLC

PDCP

RRC

PHY

MAC

RLC

PDCP

RRCIP IP

IP IP

Applications ApplicationsNAS NAS

CONTROL PLANE CONTROL PLANEUSER PLANE USER PLANE

DRB DRB DRB DRB

L1

L2

L3

L1

L2

L3

Physical Channels Physical Channels

Transport Channels Transport Channels

Logical ChannelsLogical Channels

RLC Mode RLC Mode

Radio Bearers Radio Bearers

PBCH

The Physical Broadcast Channel carries the Master Information Block (MIB). It consists of a limited number of the most frequently transmitted parameters essential for initial access to the cell. The PBCH is designed for early detection by the UE, and cell-wide coverage

PDSCH

The Physical Downlink Shared Channel is the main downlink data-bearing channel in LTE, used for all user data, as well as for broadcast system information which is not carried on the Physical Broadcast Channel (PBCH). It is also used for paging messages.

PCFICH

The Physical Control Format Indicator Channel is a downlink physical channel that carries a Control Format Indicator (CFI) which indicates the number of OFDM symbols (i.e. normally 1, 2 or 3) used for transmission of downlink control channel information in each sub-frame.

PDCCH

Physical Downlink Control Channel in LTE carries UE-specific scheduling assignments for DL resource allocation, UL grants, PRACH responses, UL power control commands, and common scheduling assignments for signaling messages (such as system information, paging, etc.).

PHICH

The Physical Hybrid ARQ Indicator Channel is a downlink physical channel that carries the Hybrid ARQ (HARQ) ACK/NACK information indicating whether the eNB has correctly received a transmission on the PUSCH. Multiple PHICHs (for different UEs) are mapped to the same set of downlink resource elements.

PMCH

Physical Multicast Channel : For transmission of multicast and broadcast information, Format is similar to the PDSCH but it is for reception by several mobiles, Sub-channel spacing is 7.5 kHz and symbol length is doubled, Modulation QPSK, 16 QAM or 64 QAM

PUSCH

Physical Uplink Shared Channel: This channel is used to carry RRC signaling messages. Uplink RRC messages are carried using PUSCH. LTE PUSCH channel contain user information data. The PUSCH carries both user data as well as control signal data.

PUCCH

Physical Uplink Control Channel: This LTE channel is used to carry UCI. UCI can also be transported using PUSCH channel. An LTE UE can never transmits both PUCCH and PUSCH during the same sub-frame. If UE has application data then UCI is carried over PUSCH. If UE does not have data UCI is carried over PUCCH.

PRACHPhysical Random Access Channel: This channel is used to carry random access preambles used for initiation of random access procedure.

PCCH

Paging Control Channel : A downlink channel that transfers paging information and system information change notifications. This channel is used for paging when the network does not know the location cell of the UE.

BCCH

Broadcast Control Channel (BCCH) : This control channel provides system information to all mobile terminals connected to the eNodeB.It allows the UE to retrieve cell and network configuration parameters (e.g. PLMN code, cell identity, cell reselection parameters, etc.) required for normal operation within EUTRAN.

CCCH

Common Control Channel: RRC signaling channel used by UEs to do the initial access signaling when it is in RRC_IDLE state and wants to enter RRC_CONNECTED state. The UE will send only one message (RRC CONNECTION REQUEST) andthe rest of the communication takes place on DCCH.

DCCH

Dedicated Control Channel: This control channel is used for carrying user-specific control information, e.g. for controlling actions including power control, handover, etc..

DTCH

Dedicated Traffic Channel: The DTCH is used for user radio bearers carrying IP traffic. The eNB connects DTCHs with their associated S1-U tunnel to the SAE GW. DTCH can be bidirectional, uplink only or downlink only. DTCH are of course point-to-point.

MCCH

Multicast Control Channel: The MCCH is associated with MBMS. It allows the eNB to inform UEs that want to listen to broadcast or multicast service traffic about availability of such services and about the associated MBMS radio bearer (point-to-multipoint) radio bearers.

MTCH

Multicast Traffic Channel: The MTCH is a point-to-multipoint traffic channel for MBMS. It carries IP traffic for broadcast or multicast services driven by the MBMS feature.

PCH

Paging Channel: Associated with the PCCH logical channel. It is mapped to dynamically allocated physical resources, and is required for broadcast over the entire cell coverage area. It is transmitted on the Physical Downlink Shared Channel

BCH

Broadcast Channel: A downlink channel associated with the BCCH logical channel and is used to broadcast system information over the entire coverage area of the cell. It has a fixed transport format defined by the specifications.

DL-SCH

Downlink Shared Channel: Used for transmitting the downlink data, including both control and traffic data, and thus it is associated with both logical control and logical traffic channels.

RACH

Random Access Channel: A specific transport channel that is not mapped to any logical channel. It transmits relatively small amounts of data for initial access or, in the case of RRC, state changes.

MCH

Multicast Channel: Associated with MCCH and MTCH logical channels for the multicast/broadcast service. It supports Multicast/Broadcast Single Frequency Network (MBSFN) transmission, which transmits the same information on the same radio resource from multiple synchronized base stations to multiple UEs.

UL-SCH

Uplink Shared Channel: The uplink counterpart of the DL-SCH. It can be associated to CCCH, DCCH, and DTCH logical channels. It supports H-ARQ, dynamic link adaption, and dynamic and semi-persistent resource allocation.

DCI

Downlink Control Information: It carries information related to downlink/uplink scheduling assignment, modulation and coding scheme, and Transmit Power Control (TPC) command, and is sent over the Physical Downlink Control Channel (PDCCH). The DCI supports 10 different formats.

CFI

Control Format Indicator: It indicates how many symbols the DCI spans in that sub-frame. It takes values CFI = 1, 2, or 3, and is sent over the Physical Control Format Indicator Channel (PCFICH).

TM

TM is the simplest RLC mode. TM stands for 'Transparent Mode'. The term 'Transparent' may have many different meaning. In this case, it would mean 'the contents goes through this layer without any modification'.

AM

Most complicated RLC type. 'AM' stands for 'Acknowledge Mode'. As it's name implies it requires ACK/NACK from the other party. It is more like TCP packet in IP world, whereas RLC UM is more like UDP in IP world.

UM

UM stands for 'Unacknowledged Mode'. 'UM' means 'it does not require any reception response from the other party'. 'Reception response' simply mean 'ACK' or 'NACK' from the other party. (UM mode is similar to TM mode in that it does not require any ACK/NACK from the other party).

SRB

Both signaling radio bearers are used to transmit/receive LTE signaling messages. SRB2 is used specifically for NAS signaling messages but if SRB2 is not at all present or established, SRB1 is used to trans/receive NAS messages.

DRBData Radio Bearer: to carry user data. Data radio bearer transports the packets of an EPS bearer between a UE and an eNedeB.

ROHCRobust Header Compression is a standardized method to compress the IP, UDP, UDP-Lite, RTP, and TCP headers of Internet packets.

IntegrityIntegrity Protection applies only to C-Plane data (C-Plane data means RRC/NAS message, i.e DCCH data, not DTCH data).

Ciphering

Ciphering Protection applies both C-Plane and U-Plane Data.

TCP

TCP (Transmission Control Protocol) is the most commonly used protocol on the Internet. The reason for this is because TCP offers error correction. When the TCP protocol is used there is a "guaranteed delivery." This is due largely in part to a method called "flow control." Flow control determines when data needs to be re-sent, and stops the flow of data until previous packets are successfully transferred. This works because if a packet of data is sent, a collision may occur. When this happens, the client re-requests the packet from the server until the whole packet is complete and is identical to its original.

UDP

UDP (User Datagram Protocol) is anther commonly used protocol on the Internet. However, UDP is never used to send important data such as webpages, database information, etc; UDP is commonly used for streaming audio and video. Streaming media such as Windows Media audio files (.WMA) , Real Player (.RM), and others use UDP because it offers speed! The reason UDP is faster than TCP is because there is no form of flow control or error correction. The data sent over the Internet is affected by collisions, and errors will be present. Remember that UDP is only concerned with speed. This is the main reason why streaming media is not high quality.

HI

H-ARQ Indicator: It carries H-ARQ acknowledgment in response to uplink transmissions, and is sent over the Physical Hybrid ARQ Indicator Channel (PHICH). HI = 1 for a positive acknowledgment (ACK) and HI = 0 for a negative acknowledgment (NAK).

UCI

Uplink Control Information: It is for measurement indication on the downlink transmission, scheduling request of uplink, and the H-ARQ acknowledgment of downlink transmissions. The UCI can be transmitted either on the Physical Uplink Control Channel (PUCCH) or the Physical Uplink Shared Channel.

Application

IP

PDCP

RLC

MAC

PHY

PDCP

RLC

MAC

PHY

L2

L1

GTP-U UDP/IP

IP Sec

L1

L2

L1

GTP-U UDP/IP

IP Sec

GTP-U UDP/IP

IP Sec

L2

L1

L2

L1

IP Services

GTP-U UDP/IP

IP Sec

L2

NAS

RRC

PDCP

RLC

MAC

PHY

NAS

S1-AP

SCTP

IP

L2

L1

RRC

PDCP

RLC

MAC

PHY

S1-AP

SCTP

IP

L2

L1

UE eNodeB S-GW P-GW

UE eNodeB MME

Use

r Pla

neCo

ntro

l pla

ne

Uu S1-MME

Uu S1-U S5/S8 SGi

LTE Radio Protocol Stack

Prepared by Ziya Akhundov

Relay Relay

Relay

HARQ,CRC, Coding, De-Scrambling, De-Modulation, Measurement, Resource Element De-Mapping, MIMO

Channel Mapping, De-Multiplexing, Handling Control Elements, HARQ, DRX

HARQ,CRC, Coding, Scrambling, Modulation, Measurement, Resource Element Mapping, MIMO

Channel Mapping, Multiplexing, Handling Control Elements, HARQ, Random Access Procedure, Logical Channel Priority, Sending BSR

Re-Ordering, Reassembly, ARQ (for AM mode)

Buffer Status Report, Segment & Concatenation, ARQ (for AM mode)

In Sequence Delivery, Duplicate Packet Detection, Integrity Validation, De-ciphering, Header-Decompression

Sequence Number Addition, Hand Over Data Handling, Integrity Protection, Ciphering, Header-Compression

Mobility Management, Configuration Management, Connection Management, Paging Control, Security Management, Broadcast, Measurement Configuration, Measurement Reporting, Cell Selection/Reselection

Mobility Management, Configuration Management, Connection Management, Paging Control, Security Management, Broadcast, Measurement Configuration, Measurement Reporting, Cell Selection/Reselection

Mobility Management, Session Management, Bearer Management, Paging Control, Security Management

Mobility Management, Session Management, Bearer Management, Paging Control, Security Management