LTE Packet Core Systems – Mobility and QoS
Long-Term Evolution (LTE) enhances the success of HSPA with better height statistics quotes, lower latency and a more suitable broadband revel in high-demand regions. This is performed with using wider-spectrum bandwidths, OFDMA and SC-FDMA air interfaces, and superior antenna strategies. These techniques enable high spectral performance and a wonderful user revel in for a huge variety of converged IP services. To take full advantage of that broadband get admission to networks and to allow the co-existence of a couple of technologies via a green, all-in-packet architecture, 3GPP implemented a brand new middle community, the developed packet center (EPC). EPC is planned for 3GPP Release nine and is supposed for use by using various get entry to networks including LTE, HSPA/HSPA+, and non-3GPP networks. The evolved packet system (EPS) contains the EPC and a set of get right of entry to structures which include the eUTRAN or UTRAN. EPS has been designed from the ground up to aid seamless mobility and QoS with minimal latency for IP services.
EVOLVING ALL-IP FLAT ARCHITECTURE
The 3GPP is evolving wireless networks to become flatter and more simplified. In EPS’ consumer aircraft, as an instance, there are handiest varieties of nodes (base stations and gateways), whilst in contemporary hierarchical networks, there are 4 types, including a centralized RNC. Another simplification is the separation of the control plane, with a separate mobility-management network element. It is well worth noting that similar optimizations are enabled inside the developed HSPA community architecture, offering a likewise flattened architecture.
A key distinction from current networks is that the EPC is described to guide packet-switched site visitors simplest. Interfaces are primarily based on IP protocols. This means that all services can be introduced via packet connections, together with voice. Thus, EPS gives savings for operators through the usage of an unmarried-packet community for all offerings.
EVOLVED NODE-B (eNB)
A great fact is that most of the everyday protocols implemented in modern-day RNC are moved to the eNB. The eNB, much like the Node B functionality within the developed HSPA architecture, is also chargeable for header compression, ciphering and reliable shipping of packets. On the managed aircraft, capabilities inclusive of admission manage and radio useful resource control also are incorporated into the eNB. Benefits of the RNC and Node B merger consist of decreased latency with fewer hops within the media route, and distribution of the RNC processing load into a couple of eNBs.
SERVING AND PDN GATEWAYS
Between the get entry to network and the PDNs (e.G., the Internet), gateways assist the interfaces, the mobility core desires and the differentiation of QoS flows. EPS defines logical gateway entities, the S-GW and the P-GW. The S-GW acts as a neighborhood mobility vans anchor, forwarding and receiving packets to and from the eNB in which the UE is being served. The P-GW, in turn, interfaces with the external PDNs, including the Internet and IMS. It is likewise answerable for numerous IP capabilities, which includes deal with allocation, policy enforcement, packet classification and routing, and it affords mobility anchoring for non-3GPP get admission to networks. In the exercise, both gateways can be implemented as one bodily community detail, depending on deployment scenarios and dealer help.
MOBILITY MANAGEMENT ENTITY (MME)
The MME is a signaling-best entity, hence consumer IP packets do no longer undergo the MME. Its major feature is to manipulate the UE’s mobility. In addition, the MME additionally plays authentication and authorization; idle-mode UE monitoring and reachability; security negotiations; and NAS signaling. A gain of a separate community element for signaling is that operators can grow signaling and site visitors ability independently. A similar advantage also can be executed in HSPA Release 7’s direct-tunnel architecture, wherein the SGSN will become a signaling-most effective entity.
An important thing for any all-packet network is a mechanism to guarantee differentiation of packet flows primarily based on its QoS requirements. Applications together with video streaming, HTTP, or video telephony have unique QoS desires and have to acquire differentiated provider over the network. With EPS, QoS flows referred to as EPS bearers are installed between the UE and the P-GW. Each EPS bearer is related to a QoS profile and consists of a radio bearer and a mobility vans tunnel. Thus, each QoS IP float (e.G., VoIP) will be associated with a distinct EPS bearer, and the network can prioritize packets accordingly. The QoS system for packets arriving from the Internet is similar to that of HSPA. When receiving an IP packet, the P-GW plays packet category primarily based on parameters which include policies acquired from the PCRF, and sends it through the proper mobility tunnel. Based at the mobility tunnel, the eNB can map packets to the ideal radio QoS bearer.
EPS SEAMLESS MOBILITY
Seamless mobility is definitely a key consideration for wi-fi systems. Uninterrupted lively handoff across eNBs is the primary scenario one commonly considers. However, different situations such as handoffs across middle networks (i.E., P-GW, MME), transfer of get admission to technologies, and idle mobility also are essential scenarios included by EPS.
SEAMLESS ACTIVE HANDOFFS
EPS enables seamless lively handoffs, helping VoIP and other real-time IP applications. Since there is no RNC, an interface among eNBs is used to aid signaling for handoff coaching. In addition, the S-GW behaves as an anchor, switching mobility tunnels across eNBs. A serving eNB maintains the coupling among mobility vans tunnels and radio bearers, and also maintains the UE context1. As practise for handoff, the supply eNB (eNB 1) sends the coupling statistics and the UE context to the target eNB (eNB 2). This signaling is triggered by a radio measurement from the UE, indicating that eNB 2 has a higher sign. Once eNB 2 signals that it is ready to carry out the handoff, eNB 1 instructions the UE to trade the radio bearer to eNB 2. For the eNB handoff to complete, the S-GW must replace its information with the brand new eNB that is serving the UE. For this segment, MME coordinates the mobility-tunnel switch from eNB 1 to eNB 2. MME triggers the replace on the S-GW, primarily based on signaling received from eNB 2 indicating that the radio bearer turned into correctly transferred.
EFFICIENT IDLE MOBILITY
An extra mobility element to don’t forget with a brand new wi-fi core network is the mechanism to pick out the approximate location of the UE whilst it is not energetic. EPS gives an efficient solution for idle mobility management. The basic idea is to companion a cluster of eNBs into monitoring areas (TAs). The MME tracks which TA the UE is in, and if the UE movements to a distinct TA, the UE updates the MME with its new TA. When the EPS GW gets statistics for an idle UE, it will buffer the packets and question the MME for the UE’s area. Then the MME will webpage the UE in its maximum cutting-edge TA. EPS consists of a new concept, that is the ability of a UE to be registered in more than one TAs simultaneously. This allows the UE to decrease battery consumption at some point of periods of high mobility vans because it does not need to constantly update its region with the MME. It also minimizes the registration load on TA barriers.
HETEROGENOUS NETWORK MOBILITY
LTE is predicted as a complement to modern-day HSPA/HSPA+ networks in places which have a high call for records and superior broadband revel in. Therefore, LTE gets entry to networks will co-exist with the giant insurance of HSPA/HSPA+ networks, thus requiring robust mechanisms to interoperate. For information interoperability, EPC will aid interfaces among the existing SGSNs and the MME and S-GW, that allows you to allow statistics handoffs. For voice-provider continuity, 3GPP is likewise working on standardizing a voice-name continuity approach a good way to allow seamless operation between VoIP over LTE and circuit-switched voice over R99.
EPS provides operators with efficient and strong middle network architecture to assist all IP offerings for LTE, HSPA and non-3GPP get right of entry to networks. Fundamentally, it is a flattened architecture that permits simplified network design at the same time as still helping seamless mobility vans and superior QoS mechanisms. Many of the standard RNC functions are integrated into the eNB, and the EPS defines a control plane with a separate community element, the MME. QoS logical connections are set up among the UE and the EPS GW, offering differentiation of IP flows throughout the whole network, and assembly the requirements for low-latency applications. The principles and design are much like the evolved HSPA architecture, supplying operators with an easy migration path for their 3GPP core networks.