Abstrct
The goal of the Lte proper is to create specifications for a new radio-access technology geared to higher data rates, low latency and greater spectral efficiency. The spectral efficiency target for the Lte ideas is three to four times higher than the current Hspa system. These aggressive spectral efficiency targets require using the technology envelope by employing industrialized air-interface techniques such as low-Papr orthogonal uplink manifold passage based on Sc-Fdma(single-carrier frequency department manifold access) Mimo multiple-input multiple-output multi-antenna technologies, inter-cell interference mitigation techniques, low latency channel structure and single-frequency network (Sfn) broadcast. The researchers and engineers working on the proper come up with new innovative technology proposals and ideas for ideas doing improvement. Due to the very aggressive proper amelioration schedule, these researchers and engineers are generally unable to release their proposals in conferences or journals, etc. In the standards amelioration phase, the proposals go through ample scrutiny with manifold sources evaluating and simulating the proposed technologies from ideas doing correction and implementation complexity perspectives. Therefore, only the highest-quality proposals and ideas ultimately make into the standard.
Related 4G mobile Broadband - Lte Network Architecture and Protocol Stack.
Keywords: Lte Architecture, Udp, Gdp, Mimo, Mime, Mcch, Mbms, Qos
Recommend 4G mobile Broadband - Lte Network Architecture and Protocol Stack.
1. Introducyion
The Lte network architecture is designed with the goal of supporting packet-switched traffic with seamless mobility, potential of service (QoS) and minimal latency. A packet-switched approach allows for the supporting of all services including voice through packet connections. The effect in a very simplified flatter architecture with only two types of node namely evolved Node-B (eNb) and mobility administration entity/gateway (Mme/Gw). This is in divergence to many more network nodes in the current hierarchical network architecture of the 3G system. One major convert is that the radio network controller (Rnc) is eliminated from the data path and its functions are now incorporated in eNb. Some of the benefits of a single node in the passage network are reduced latency and the distribution of the Rnc processing load into manifold eNbs. The elimination of the Rnc in the passage network was possible partly because the Lte ideas does not retain macro-diversity or soft-handoff.
2. Lte Network Architecture
All the network interfaces are based on Ip protocols. The eNbs are interconnected by means of an X2 interface and to the Mme/Gw entity by means of an S1 interface as shown in Figure1. The S1 interface supports a many-to-many relationship between Mme/Gw and eNbs.
The functional split between eNb and Mme/Gw is shown in frame 2 Two logical gateway entities namely the serving gateway (S-Gw) and the packet data network gateway (P-Gw) is defined. The S-Gw acts as a local mobility anchor forwarding and receiving packets to and from the eNb serving the Ue. The P-Gw interfaces with external packet data networks (Pdns) such as the Internet and the Ims. The P-Gw also performs several Ip functions such as address allocation, procedure enforcement, packet filtering and routing.
The Mme is a signaling only entity and hence user Ip packets do not go through Mme. An benefit of a separate network entity for signaling is that the network capacity for signaling and traffic can grow independently. The main functions of Mme are idle-mode Ue reach potential including the control and doing of paging retransmission, tracking area list management, roaming, authentication, authorization, P-Gw/S-Gw selection, bearer administration including dedicated bearer establishment, protection negotiations and Nas signaling, etc.
Evolved Node-B implements Node-B functions as well as protocols traditionally implemented in Rnc. The main functions of eNb are header compression, ciphering and reliable delivery of packets. On the control side, eNb incorporates functions such as admission control and radio reserved supply management. Some of the benefits of a single node in the passage network are reduced latency and the distribution of Rnc the network side are now ended in eNb.
Figure 1: Network Architecture
Figure 2: Functional split between eNb and Mme/Gw.
2.1 Protocol Stack And Conytol Plane
The user plane protocol stack is given in frame 3.We note that packet data convergence protocol (Pdcp) and radio link control (Rlc) layers traditionally ended in Rnc on frame 4 shows the control plane protocol stack.
Figure 3: User plane protocol.
Figure 4: control plane protocol stack.
We note that Rrc functionality traditionally implemented in Rnc is now incorporated into eNb. The Rlc and Mac layers achieve the same functions as they do for the user plane. The functions performed by the Rrc consist of ideas data broadcast, paging, radio bearer control, Rrc relationship management, mobility functions and Ue measurement reporting and control. The non-access stratum (Nas) protocol ended in the Mme on the network side and at the Ue on the terminal side performs functions such as Eps (evolved packet system) bearer management, authentication and protection control, etc.
The S1 and X2 interface protocol stacks are shown in Figures 2.5 and 2.6 respectively.We note that similar protocols are used on these two interfaces. The S1 user plane interface (S1-U) is defined between the eNb and the S-Gw. The S1-U interface uses Gtp-U (Gprs tunneling protocol - user data tunneling) on Udp/Ip vehicle and provides non-guaranteed delivery of user plane Pdus between the eNb and the S-Gw. The Gtp-U is a relatively straightforward Ip based tunneling protocol that permits many tunnels between each set of end points. The S1 control plane interface (S1-Mme) is defined as being between the eNb and the Mme. Similar to the user plane, the vehicle network layer is built on Ip vehicle and for the reliable
Figure 5: S1 interface user and control planes.
Figure 6: X2 interface user and control planes.
Transport of signaling messages Sctp (stream control transmission protocol) is used on top of Ip The Sctp protocol operates analogously to Tcp ensuring reliable, in-sequence vehicle of messages with congestion control. The application layer signaling protocols are referred to as S1 application protocol (S1-Ap) and X2 application protocol (X2-Ap) for S1 and X2 interface control planes respectively.
3. Qos And Bearer service Architecture
Applications such as VoIp, web browsing, video telephony and video streaming have extra QoS needs. Therefore, an prominent feature of any all-packet network is the provision of a QoS mechanism to enable differentiation of packet flows based on QoS requirements. In Eps, QoS flows called Eps bearers are established between the Ue and the P-Gw as shown in frame 7. A radio bearer transports the packets of an Eps bearer between a Ue and an eNb. Each Ip flow (e.g. VoIp) is linked with a separate Eps bearer and the network can prioritize traffic accordingly.
Figure 7: Eps bearer service architecture.
When receiving an Ip packet from the Internet, P-Gw performs packet classification based on safe bet predefined parameters and sends it an proper Eps bearer. Based on the Eps bearer, eNb maps packets to the proper radio QoS bearer. There is one-to-one mapping between an Eps bearer and a radio bearer.
4. Layer 2 Structure
The layer 2 of Lte consists of three sub layers namely medium passage control, radio link control (Rlc) and packet data convergence protocol (Pdcp). The service passage point (Sap) between the corporal (Phy) layer and the Mac sub layer furnish the vehicle channels while the Sap between the Mac and Rlc sub layers furnish the logical channels. The Mac sub layer performs multiplexing of logical channels on to the vehicle channels.
The downlink and uplink layer 2 structures are given in Figures 8 and 9 respectively. The divergence between downlink and uplink structures is that in the downlink, the Mac sub layer also handles the priority among Ues in addition to priority handling among the logical channels of a single Ue. The other functions performed by the Mac sub layers in both downlink and uplink consist of mapping between the logical and the vehicle channels.
Multiplexing of Rlc packet data units (Pdu), padding, vehicle format choice and hybrid Arq (Harq).
The main services and functions of the Rlc sub layers consist of segmentation, Arq in-sequence delivery and double detection, etc. The in-sequence delivery of upper layer Pdus is not guaranteed at handover. The reliability of Rlc can be configured to either sass mode (Am) or un-acknowledge mode (Um) transfers. The Um mode can be used for radio bearers that can tolerate some loss. In Am mode, Arq functionality of Rlc Retransmits vehicle blocks that fail rescue by Harq. The rescue at Harq may fail due to hybrid Arq Nack to Ack error or because the maximum whole of retransmission attempts is reached. In this case, the relevant transmitting Arq entities are notified and possible retransmissions and re-segmentation can be initiated.
Figure 8: Downlink layer 2 structure.
Figure 9: Uplink layer 2 structure.
The Pdcp layer performs functions such as header compression and decompression, ciphering and in-sequence delivery and double detection at handover for Rlcam, etc. The header compression and decompression is performed using the robust header compression (Rohc) protocol. 5.1 Downlink logical, vehicle and corporal channels
4.1 Downlink Logical, vehicle And corporal Channels
The relationship between downlink logical, vehicle and corporal channels is shown in frame 10. A logical channel is defined by the type of data it carriers. The logical channels are further divided into control channels and traffic channels. The control channels carry control-plane information, while traffic channels carry user-plane information.
In the downlink, five control channels and two traffic channels are defined. The downlink control channel used for paging data replacement is referred to as the paging control channel (Pcch). This channel is used when the network has no knowledge about the location cell of the Ue. The channel that carries ideas control data is referred to as the broadcast control channel (Bcch). Two channels namely the tasteless control channel (Ccch) and the dedicated control channel (Dcch) can carry data between the network and the Ue. The Ccch is used for Ues that have no Rrc relationship while Dcch is used for Ues that have an Rrc connection. The control channel used for the transmission of Mbms control data is referred to as the multicast control channel (Mcch). The Mcch is used by only those Ues receiving Mbms.
The two traffic channels in the downlink are the dedicated traffic channel (Dtch) and the multicast traffic channel (Mtch). A Dtch is a point-to-point channel dedicated to a single Ue for the transmission of user information. An Mtch is a point-to-multipoint channel used for the transmission of user traffic to Ues receiving Mbms. The paging control channel is mapped to a vehicle channel referred to as paging channel (Pch). The Pch supports discontinuous reception (Drx) to enable Ue power saving. A Drx cycle is indicated to the Ue by the network. The Bcch is mapped to either a vehicle channel referred to as a broadcast channel (Bch) or to the downlink shared channel (Dlsch).
Figure 10: Downlink logical, vehicle and corporal channels mapping.
The Bch is characterized by a fixed pre-defined format as this is the first channel Ue receives after acquiring synchronization to the cell. The Mcch and Mtch are either mapped to a vehicle channel called a multicast channel (Mch) or to the downlink shared channel (Dl-Sch). The Mch supports Mbsfn combining of Mbms transmission from manifold cells. The other logical channels mapped to Dl-Sch consist of Ccch, Dcch and Dtch. The Dl-Sch is characterized by retain for adaptive modulation/coding, Harq, power control, semi-static/dynamic reserved supply allocation, Drx, Mbm Transmission and multi antenna technologies. All the four-downlink vehicle channels have the requirement to be broadcast in the entire coverage area of a cell.
The Bch is mapped to a corporal channel referred to as corporal broadcast channel (Pbch), which is transmitted over four sub frames with 40 ms timing interval. The 40 ms timing is detected blindly without requiring any explicit signaling. Also, each sub frame transmission of Bch is self-decodable and Ues with good channel conditions may not need to wait for reception of all the four sub frames for Pbch decoding. The Pch and Dl-Sch are mapped to a corporal channel referred to as corporal downlink shared channel (Pdsch). The multicast channel (Mch) is mapped to corporal multicast channel (Pmch), which is the multi-cell Mbsfn transmission channel.
The three stand-alone corporal control channels are the corporal control format indicator channel (Pcfich), the corporal downlink control channel (Pdcch) and the corporal hybrid Arq indicator channel (Phich). The Pcfich is transmitted every sub frame and carries data on the whole of Ofdm symbols used for Pdcch. The Pdcch is used to clue the Ues about the reserved supply allocation of Pch and Dl-Sch as well as modulation, coding and hybrid Arq data linked to Dl-Sch. A maximum of three or four Ofdm symbols can be used for Pdcch. With dynamic indication of whole of Ofdm symbols used for Pdcch via Pcfich, the unused Ofdm symbols among the three or four Pdcch Ofdm symbols can be used for data transmission. The Phich is used to carry hybrid Arq Ack/Nack for uplink transmissions.
4.2 Uplink Logical, vehicle And corporal Channels
The relationship between uplink logical, vehicle and corporal channels is shown in frame 2.11. In the uplink two control channels and a single traffic channel is defined. As for the downlink, tasteless control channel (Ccch) and dedicated control channel (Dcch) are used to carry data between the network and the Ue. The Ccch is used for Ues having no Rrc relationship while Dcch is used for Ues having an Rrc connection. Similar to downlink, dedicated traffic channel (Dtch) is a point-to-point channel dedicated to a single Ue for transmission of user information. All the three uplink logical channels are mapped to a vehicle channel named uplink shared channel (Ul-Sch). The Ul-Sch supports adaptive modulation/coding, Harq, power control and semi-static/dynamic reserved supply allocation.
Another vehicle channel defined for the uplink is referred to as the random passage channel (Rach), which can be used for transmission of exiguous control data from a Ue with possibility of collisions with transmissions from other Ues. The Rach is mapped to corporal random passage channel (Prach), which carries the random passage preamble.
The Ul-Sch vehicle channel is mapped to corporal uplink shared channel (Pusch). A stand-alone uplink corporal channel referred to as corporal uplink control channel (Pucch) is used to carry downlink channel potential indication (Cqi) reports, scheduling ask (Sr) and hybrid Arq Ack/Nack for downlink transmissions.
5. Protocol States And States Transitions
In the Lte system, two radio reserved supply control (Rrc) states namely Rrc Idle and Rrc linked states are defined as depicted in frame 2.12. A Ue moves from Rrc Idle state to Rrc linked state when an Rrc relationship is successfully established. A Ue can move back from Rrc linked to Rrc Idle state by releasing the Rrc connection. In the Rrc Idle state, Ue can receive broadcast/multicast data, monitors a paging channel to detect incoming calls, performs neighbor cell measurements and cell selection/reselection and acquires ideas information. Furthermore, in the Rrc Idle state, a Ue definite Drx (discontinuous reception) cycle may be configured by upper layers to enable Ue power savings. Also, mobility is controlled by the Ue in the Rrc Idle
State.
In the Rrc linked state, the replacement of uncast data to/from Ue, and the replacement of broadcast or multicast data to Ue can take place. At lower layers, the Ue may be configured with a Ue definite Drx/Dtx (discontinuous transmission). Furthermore, Ue monitors control channels linked with the shared data channel to decree if data is scheduled for it, provides channel potential feedback information, performs neighbor cell measurements and measurement reporting and acquires ideas information. Unlike the Rrc Idle state, the mobility is controlled by the network in this state.
Figure 11 Uplink logical, vehicle and corporal channels mapping.
Figure 12: Ue states and state transitions.
6. Seamless Mobility Support
An prominent feature of a mobile wireless ideas such as Lte is retain for seamless mobility over eNbs and over Mme/Gws. Fast and seamless handovers (Ho) is particularly prominent for delay-sensitive services such as VoIp. The handovers occur more frequently over eNbs than over core networks because the area covered by Mme/Gw serving a large whole of eNbs is generally much larger than the area covered by a single eNb. The
signaling on X2 interface between eNbs is used for handover preparation. The S-Gw acts as anchor for inter-eNb handovers.
In the Lte system, the network relies on the Ue to detect the neighboring cells for handovers and therefore no neighbor cell data is signaled from the network. For the quest and measurement of inter-frequency neighboring cells, only the carrier frequencies need to be indicated. An example of active handover in an Rrc linked state is shown in frame 13 where a Ue moves from the coverage area of the source eNb (eNb1) to the coverage area of the target eNb (eNb2). The handovers in the Rrc linked state are network controlled and assisted by the Ue. The Ue sends a radio measurement description to the source eNb1 indicating that the signal potential on eNb2 is best than the signal potential on eNb1. As preparing for handover, the source eNb1 sends the coupling data and the Ue context to the target eNb2 (Ho request) [6] on the X2 interface. The target eNb2 may achieve admission control dependent on the received Eps bearer QoS information. The target eNb configures the required resources according to the received Eps bearer QoS data and reserves a C-Rnti (cell radio network temporary identifier) and optionally a Rach preamble.
Figure 13: Active handovers.
The C-Rnti provides a unique Ue identification at the cell level identifying the Rrc connection. When eNb2 signals to eNb1 that it is ready to achieve the handover via Ho response message, eNb1 commands the Ue (Ho command) to convert the radio bearer to eNb2. The Ue receives the Ho command with the needful parameters (i.e. New C-Rnti, optionally dedicated Rach preamble, possible expiry time of the dedicated Rach preamble, etc.) and is commanded by the source eNb to achieve the Ho. The Ue does not need to delay the handover doing for delivering the Harq/Arq responses to source eNb.
After receiving the Ho command, the Ue performs synchronization to the target eNb and accesses the target cell via the random passage channel (Rach) following a contention-free procedure if a dedicated Rach preamble was allocated in the Ho command or following a contention-based procedure if no dedicated preamble was allocated. The network responds with uplink reserved supply allocation and timing strengthen to be applied by the Ue. When the Ue has successfully accessed the target cell, the Ue sends the Ho confirm message (C-Rnti) along with an uplink buffer status description indicating that the handover procedure is completed for the Ue. After receiving the Ho confirm message, the target eNb sends a path switch message to the Mme to clue that the Ue has changed cell. The Mme sends a user plane modernize message to the S-Gw. The S-Gw switches the downlink data path to the target eNb and sends one or more "end marker" packets on the old path to the source eNb and then releases any user-plane/Tnl resources towards the source eNb. Then S-Gw sends a user plane modernize response message to the Mme. Then the Mme confirms the path switch message from the target eNb with the path switch response message. After the path switch response message is received from the Mme, the target eNb informs success of Ho to the source eNb by sending release reserved supply message to the source eNb and triggers the release of resources. On receiving the release reserved supply message, the source eNb can release radio and C-plane linked sources linked with the Ue context.
During handover preparing U-plane tunnels can be established between the source Enb and the target eNb. There is one tunnel established for uplink data forwarding and someone else one for downlink data forwarding for each Eps bearer for which data forwarding is applied. During handover execution, user data can be forwarded from the source eNb to the target eNb. Forwarding of downlink user data from the source to the target eNb should take place in order as long as packets are received at the source eNb or the source eNb buffer is exhausted.
For mobility administration in the Rrc Idle state, thought of tracking area (Ta) is introduced. A tracking area generally covers manifold eNbs as depicted in frame 2.14. The tracking area identity (Tai) data indicating which Ta an eNb belongs to is broadcast as part of ideas information. A Ue can detect convert of tracking area when it receives a separate Tai than in its current cell. The Ue updates the Mme with its new Ta data as it moves over Tas. When P-Gw receives data for a Ue, it buffers the packets and queries the Mme for the Ue's location. Then the Mme will page the Ue in its most current Ta. A Ue can be registered in manifold Tas simultaneously. This enables power rescue at the Ue under conditions of high mobility because it does not need to constantly modernize its location with the Mme. This feature also minimizes load on Ta boundaries.
8. Multicast Broadcast ideas Architecture
In the Lte system, the Mbms either use a single-cell transmission or a multi-cell transmission. In single-cell transmission, Mbms is transmitted only in the coverage of a definite cell and therefore combining Mbms transmission from manifold cells is not supported. The single-cell Mbms transmission is performed on Dl-Sch and hence uses the same network architecture as the unicast traffic.
Figure 14: Tracking area modernize for Ue in Rrc Idle state.
The Mtch and Mcch are mapped on Dl-Sch for point-to-multipoint transmission and scheduling is done by the eNb. The Ues can be allocated dedicated uplink feedback channels selfsame to those used in unicast transmission, which enables Harq Ack/Nack and Cqi feedback. The Harq retransmissions are made using a group (service specific) Rnti (radio network temporary identifier) in a time frame that is co-ordinated with the former Mtch transmission. All Ues receiving Mbms are able to receive the retransmissions and concentrate with the former transmissions at the Harq level. The Ues that are allocated a dedicated uplink feedback channel are in Rrc linked state. In order to avoid unnecessary Mbms transmission on Mtch in a cell where there is no Mbms user, network can detect proximity of users curious in the Mbms service by polling or through Ue service request.
The multi-cell transmission for the evolved multimedia broadcast multicast service (Mbms) is realized by transmitting selfsame waveform at the same time from manifold cells. In this case, Mtch and Mcch are mapped on to Mch for point-to-multipoint transmission. This multi-cell transmission mode is referred to as multicast broadcast single frequency network (eMbsfn) as described in detail in chapter 17. An Mbsfn transmission from manifold cells within an Mbsfn area is seen as a single transmission by the Ue. An Mbsfn area comprises a group of cells within an Mbsfn synchronization area of a network that are co-ordinate to achieve Mbsfn transmission. An Mbsfn synchronization area is defined as an area of the network in which all eNbs can be synchronized and achieve Mbsfn transmission. An Mbms service area may consist of manifold Mbsfn areas. A cell within an Mbsfn synchronization area may form part of manifold Sfn areas each characterized by separate article and set of participating cells.
Figure 15. The eMbms service area and Mbsfn areas.
An example of Mbms service area consisting of two Mbsfn areas, area A and area B, is depicted in frame 2.15. The Mbsfna area consists of cells A1-A5, cell Ab1 and Ab2. The Mbsfn area consists of cells B1-B5, cell Ab1 and Ab2. The cells Ab1 and Ab2 are part of both Mbsfn area A and area B. The cell B5 is part of area B but does not contribute to Mbsfn transmission. Such a cell is referred to as Mbsfn area reserved cell. The Mbsfn area reserved cell may be allowed to forward for other services on the resources allocated for the Mbsfn but at a restricted power. The Mbsfn synchronization area, the Mbsfn area and reserved cells can be semi-statically configured by O&M.
The Mbms architecture for multi-cell transmission is depicted in frame 2.16. The multicell multicast coordination entity (Mce) is a logical entity, which means it can also be part of someone else network element such as eNb. The Mce performs functions such as the allocation of the radio resources used by all eNbs in the Mbsfn area as well as determining the radio configuration including the modulation and coding scheme. The Mbms Gw is also a logical entity whose main function is sending/broadcasting Mbms packets with the Sync protocol to each eNb transmitting the service. The Mbms Gw hosts the Pdcp layer of the user plane and uses Ip multicast for forwarding Mbms user data to eNbs.
The eNbs are linked to eMbms Gw via a pure user plane interface M1. As M1 is a pure user plane interface, no control plane application part is defined for this interface. Two control plane interfaces M2 and M3 are defined. The application part on M2 interface conveys radio configuration data for the multi-cell transmission mode eNbs. The application part on M3 interface between Mbms Gw and Mce performs Mbms session control signaling on Eps bearer level that includes procedures such as session start and stop.
An prominent requirement for multi-cell Mbms service transmission is Mbms article synchronization to enable Mbsfn operation. The eMbms user plane architecture for article synchronization is depicted in frame 2.17. A Sync protocol layer is defined on the vehicle network layer (Tnl) to retain the article synchronization mechanism. The Sync protocol carries further data that enables eNbs to identify the timing for radio frame transmission as well as detect packet loss.
Figure 16: eMbms logical architecture.
Figure 17: The eMbms user plane architecture for article synchronization.
The eNbs participating in multicell Mbms transmission are required to comply with article synchronization mechanism. An eNb transmitting only in single-cell service is not required to comply with the stringent timing requirements indicated by Sync protocol. In case Pdcp is used for header compression, it is settled in eMbms Gw. The Ues receiving Mtch transmissions and taking part in at least one Mbms feedback project need to be in an Rrc linked state. On the other hand, Ues receiving Mtch transmissions without taking part in an Mbms feedback mechanism can be in either an Rrc Idle or an Rrc linked state. For receiving single-cell transmission of Mtch, a Ue may need to be in Rrc linked state. The signaling by which a Ue is triggered to move to Rrc linked state solely for single-cell reception purposes is carried on Mcch.
8. Summary
The Lte ideas is based on very simplified network architecture with only two types of nodes namely eNode-B and Mme/Gw. Fundamentally, it is a flattened architecture that enables simplified network design while still supporting seamless mobility and industrialized QoS mechanisms. This is a major convert relative to former wireless networks with many more network nodes using hierarchical network architecture. The simplification of network was
partly possible because Lte ideas does not retain macro-diversity or soft-handoff and hence does not require a Rnc in the passage network for macro-diversity combining. Many of the other Rnc functions are incorporated into the eNb. The QoS logical connections are in case,granted between the Ue and the gateway enabling differentiation of Ip flows and meeting the requirements for low-latency applications.
A separate architecture optimized for multi-cell multicast and broadcast is provided, which consists of two logical nodes namely the multicast co-ordination entity (Mce) and the Mbms gateway. The Mce allocates radio resources as well as determines the radio configuration to be used by all eNbs in the Mbsfn area. The Mbms gateway broadcasts Mbms packets with the Sync protocol to each eNb transmitting the service. The Mbms gateway uses Ip multicast for forwarding Mbms user data to eNbs. The layer 2 and radio reserved supply control protocols are designed to enable reliable delivery of data, ciphering, header compression and Ue power savings.
9. References
[1] 3Gppts 36.300 V8.4.0, Evolved Universal Terrestrial Radio passage Network (E-Utra): ample Description.
[2] 3Gpp Ts 29.060 V8.3.0, Gprs Tunneling Protocol (Gtp) over the Gn and Gp Interface.
[3] Ietf Rfc 4960, Stream control Transmission Protocol.
[4] Ietf Rfc 3095, Robust Header Compression (Rohc): Framework and Four Profiles: Rtp, Udp, Esp, and uncompressed.
[5] 3Gpp Ts 36.331 V8.1.0, Radio reserved supply control (Rrc) Protocol Specification.
[6] 3Gpp Tr 23.882 V1.15.1, 3Gpp ideas Architecture Evolution (Sae): description on Technical Options and Conclusions.
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