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VoLTE has been a buzzword for several years now. And for good reason. It promises multiple benefits to operators – improved efficiency, reduced OPEX, exciting new services, increased revenue and customer retention.

One would think that with so much to gain, MNOs would be jumping on the VoLTE bandwagon without any delay. However, delay has been the other buzzword closely associated with VoLTE in the past few years. When Tier 1 operators announce repeated delays, it must give us pause–what is missing? What are they overlooking?

We believe the answer lies in the complexity that is inherent in VoLTE. It is not immediately apparent and very easy to underestimate.

VoLTE requires seamless end-to-end interworking between multiple domains: Radio Access Network (eUTRAN), EPC and IMS. Mobility with legacy networks through SRVCC/eSRVCC brings in another level of complexity. Add to it the fact that a typical deployment involves multiple vendors, with their own variations of interpretation of the standards. And last but not least is what is happening in the networks themselves.

Mobile data continues to grow at an alarming rate, putting a tremendous strain on networks. Under these already challenging conditions, VoLTE introduces an extremely demanding and sensitive type of data to the network. Delivering the high quality and reliability expected of VoLTE under these trying conditions requires a new way of thinking about preparing for deployments.

The only way to be truly prepared for a successful deployment is to accurately recreate live network conditions and complexity in the lab first–with all its traffic, subscriber behavior and vendor diversity, as well as scale and volume.

EXFO QualityAssurer Simulation solution brings:

Ability to Simulate Subscribers and Network Elements

  • Any network element can be simulated
  • Any test configuration is possible ranging from end to end network testing to testing individual elements (e.g., PDN-GW) in isolation

Industry Leading Performance and Capacity to Match Live Networks

  • 40 Gbit/s (line rate) per module of real application data generation
  • 2M subscribers, 4M total bearers and 2M active bearers per module
  • 512K RTP sessions per module with real-time analysis of every session
  • 10K eNBs per module

Powerful Traffic Modeling Capabilities

  • Shape simulated user- and control-plane traffic to match live network based on:

    • Busy hour call attempts (BHCA)
    • Individual or subscriber group behavior
    • Different types of data with different QoS requirements

Comprehensive Analysis and Measurements

  • Real-time analysis of every single data session at line rate—VoLTE and other data
  • Voice quality, GBR/MBR enforcement and other measurements on every flow
  • 10 nanosecond timer resolution for accurate measurements of sensitive data
  • System and service responsiveness measurements

Unmatched Flexibility to Conquer Complexity

  • Fully stateful implementation with ability to customize
  • Quickly incorporate vendor variations, new scenarios and types of data
  • Only test tool flexible enough to test network failure scenarios

RAN Testing

This use case enables simulation of IMS along with the EPC-SIM, providing an all-in-one solution. Compatible with IR.92 and IR.94, the option enables validation of both audio and conversational video.

  • Unmatched flexibility
  • All-in-one solution (EPC, IMS, eNB, iRAT)
  • Advanced features: PWS, LBS, SON, HetNets
RAN Testing

The following is supported:

  • IMS-authentication and key agreement (AKA)-based authentication
  • Supports both session initiation protocol (SIP) and TEL URI
  • Support of real-time transport protocol (RTP) and real-time transport control protocol (RTCP)
  • Audio call: AMR-WB, AMR
  • Conversational video codec: H.264
  • Both the IPv4 and IPv6 IP address

Following VoLTE procedures:

  • VoLTE UE attachment and IMS registration
  • VoLTE UE initiated detach and IMS deregistration
  • Basic VoLTE UE to VoLTE UE voice call establishment and call clearing
  • Basic VoLTE UE to VoLTE UE multimedia (voice/video) call establishment and call clearing

End-to-End EPC Core testing

The enforcement of PCC policies is handled by the gateway elements in the EPC. Since this is such a crucial function, an important test setup would be isolating the gateway (typically the PDN-GW) for testing. The QualityAssurer can completely surround the gateway by simulating all the necessary elements. Special attention can be given in this setup to testing the enforcement of PCC functionality by the gateway.

IMS Testing

End-to-End EPC and IMS Core testing

In this scenario the system under test (SUT) is comprised of an evolved packet core (EPC) and IP multimedia subsystem (IMS). Thousands of eNBs and millions of subscribers can be simulated to recreate live network volume and scale. Simulated subscriber behavior can be modeled to reflect behavior of those subscribers in a live network. As in the real world, this can be a mix of random, unpredictable behavior of the majority of subscribers together with more predictable behavior of specific groups of subscribers.

SBC Testing

End-to-End EPC, IMS and 2G/3G Core testing

The figure below provides more coverage in terms of the network that is tested. It provides a more accurate measure of end-user experience even for iRAT scenarios. All the metrics of network performance are also relevant within this test setup. The testing does not need to be limited only to intra-LTE scenarios. It can also include iRAT mobility scenarios to 2G/3G networks. This can be accomplished by having the QualityAssurer simulate the necessary 2G/3G elements:

  • MSC for Sv and I2 interfaces needed for SRVCC
  • SGSN for S3 and S4 interfaces for handover of data sessions
  • RNC for S12 interface

Thus the QualityAssurer solution can be used to completely surround the EPC and IMS networks for testing VoLTE under real-world conditions within a single system.

End to End EPC, IMS and 2G/3G Core testing

SBC Testing

Emulate millions of VoLTE subscribers to test SBC device functions including P-CSCF, ATCF, IMS-AGW and ATGW. Quality Assurer test application sipFlex that emulates VoLTE subscriber and 2G/3G eMSC and MGW; proxyFlex that emulates P-CSCF, I-CSCF and S-CSCF; asFlex that emulates SCC-AS Application Server; and hssFlex that emulates HSS and PCRF, enables surround testing of SBC to characterize its functionality, performance, capacity, scalability and resiliency. These applications also can be used to test enhanced SRVCC (e-SRVCC) features such as alerting and mid-call.

End to End EPC Core testing

End-to-End IMS Network testing

QualityAssurer provide two applications for end-to-end testing of IMS network including VoLTE and enhanced SRVCC (e-SRVCC) features such as alerting and mid-call. In this configuration, QualityAssurer emulates millions of VoLTE/SRVCC subscribers and 2G/3G eMSC using sipFlex application, and HSS device and PCRF device using hssFlex application. These applications enables manufacturers and mobile operators to verify their IMS network in their labs before deployment by recreating and simulating the real-world network traffic patterns of millions of subscribers.

End to End EPC and IMS Core testing

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