4G LTE KEY PERFORMANCE INDICATORS

Key performance indicators of KPI’s are indicators for if a device or equipment meets a certain relaibility criteria for being ready for deployment.

The KPI’s defined are:

1.    Accessibility

2.    Retainability

3.    Integrity

4.    Availability

5.    Mobility

Business level requirements: if an end user cannot access a service it is hard to charge for the service. Also, if it happens often that an end user cannot access the provided service, the end user might change wireless subscription provider i.e loss of income for the network operator.

Specification level requirements : the accessibility of an end-user application covers a wider area than just the UTRAN part. Hence it is important to realize that a KPI for this in E-UTRAN shall be limited to the parts that E-UTRAN has control of i.e the UTRAN KPI shall be defined so that it indicates the EUTRAN contribution to the end user impact.

There are certain tests to access the accessibilty KPI:

1.    RRC connection set up for registration success rates

2.    RRC connection set up for services success rates

3.    Initial E-RAB setup success rates

4.    Successive E-RAB setup success rates

5.    Call (VOIP) setup success rates

User case description : in providing end-user services to eireless end users , the first step is to get access to the wireless service. First after access to the service has beeb performed , the service can be used. If an accessibility measurement is not considered Ok,then the network operator can investigate which steps that are required to improve the accessibilty towards their customers.

PROTOCOL SIGNALING PROCEDURES IN LTE

PROTOCOL SIGNALING PROCEDURES IN LTE

Overview:  the ever increasing growth of the internet and services has the need of more and more bandwidth. LTE promises higher data rates. 100 mbps in the downlink and 50 mbps in the uplink in LTE’s first phase it support scalable bandwidth from 1.25 mhz to 20 mhz.

Network architecture:

The architecture of LTE network is given with the various interfaces between the network elements. The functions of various elements are:

eNode:  radio resource management functions , IP header compression, encryption of user data streams, selection of an MME and transmission of paging message.

MME: it provides handovers , authentication and bearer management.

S-GW: the local anchor point of inter-eNode handover, accounting on user.

P-GW: UE IP address allocation , packet filtering , gating and rate enforcement.

BEARERS in LTE:

In LTE, end to end bearers are realized by the EPS bearers which are a collection of radio, S1 and S5/S8 bearers. An EPS bearer identify uniquely an EPS bearer for one UE accessing via E-UTRAN .

There are three kinds of bearer in LTE: radio bearers, S1 bearers and EPS bearers. In the UE, the uplink maps a traffic flow aggregate to an EPS bearer in the uplink direction and in PGW the downlink TFT maps a traffic flow aggregate to an EPS bearer in the downlink.

Radio bearer: a radio bearer transports the packets of an EPS bearer between the UE and eNode B.

S1 bearer: an S1  bearer transports the packets of an EPS bearer between an eNodeB and a S-GW.

S5/S8 bearer : it transports the packets of an EPS bearer between the S-GW and PDN GW.

SYSTEM INFORMATION BROADCASTING:
 to get service from the network , UE has to select the network a UE has to select the network and camp on a cell. For this to happen , the UE has to synchronize itself with the network at the frame and slot level. The network broadcasts this information to help the UEs in their selection process.

RANDOM ACCESS PROCEDURE—SYSTEM ACCESS

The UE can utilize the services of the network once it is synchronised in both the downlink as well as uplink direction. After the PLMN and cell selection the UE is synchronised with the network in the uplink direction. The random access procedure over PRACH is performed by the UE for this purpose. There are two types of RAPs:

Contention based Random Access Procedure: in this mode multiple UEs may attempt to access the network at the same time, thereby resulting in collisions.

Non- contention based Random access procedure : the network initiates this procedure in case of a handover of a UE from one eNode to another in order to keep handover latency under control. There are no collisions with other UE’s because the eNode controls the procedure

Enode B and E-UTRAN

                                                       Enode B        

E-UTRAN Node B also known as Evolved Node B (eNodeB or eNB) is the element in E-UTRA of LTE is the evolution of the element Node B in UTRA of UMTS.it is a hardware that is connected with mobile phone network  which communicates directly with user equipments.. in eNB there is no separate controller element. It simplifies the architecture and allows lower response times. The

eNB uses the E-UTRA protocols OFDMA  for downlink and SCFDMA for uplink on its LTE interface.it has its own functionality rather than using an Radio Network Controller. It interfaces with the System Architecture Evolution core and uses S1_MME interface with the mobility management for control traffic.

                                       E-UTRAN

The E-UTRAN consists of eNODEBs which provide E-UTRA user plane and control plane (RRC ) protocol termination toward the user equipment. The eNBs are interconnected with each other by means of the X2 interface. The eNBs are also connected by means of the s1 interface to the evolved packet core (EPC).

FUNCTIONS WITHIN THE ACCESS STRATUM:

This provides the ability , infrastructure and accessibility to the UE in acquiring the capabilities and services of the network. The radio access protocols in the E-UTRAN access stratum are comprised of numerous functionalities:

1.   RRM performs radio bearer control, admission and connection mobility control and dynamic allocation of resources to UE’s in both uplink and downlink.

2.   Traffic management in conjuction with RRM supports real and non real time user traffic between UE and architecture side.