telecom • networking • design

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QoS and Policy Management in LTE

This paper explores the growth in mobile data, and examine how this growth impacts QoE by placing heavy strains on wireless network resources. The paper reviews how wireless networks are evolving from primarily voice-only services to converged voice,
video, and data traffic, and how operators can use the emerging 3GPP standards for QoS and policy management to ease network congestion, provide higher service quality, and create a framework for new business models. Finally, we will discuss techniques to validate service quality for mobile broadband and explore a voice over LTE (VoLTE) QoS-validation use case from a tier-one operator.

LTE policy and charging control framework

LTE policy and charging control framework


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LTE User Equipment Categories

LTE supports five categories of terminals. The details of the terminal types in uplink and downlink are detailed below:

LTE UE Category: Downlink Physical Layer Parameters

UE Category Maximum number of DL-SCH transport block bits received within a TTI Maximum number of bits of a DL-SCH transport block received within a TTI Total number of soft channel bits Maximum number of supported layers for spatial multiplexing in Downlink Maximum bit rate in Downlink (Mbps)
Category 1 10296 10296 250368 1 10
Category 2 51024 51024 1237248 2 50
Category 3 102048 75376 1237248 2 75
Category 4 150752 75376 1827072 2 75
Category 5 299552 149776 3667200 4 150

LTE UE Category: Downlink Physical Layer Parameters

UE Category Maximum number of bits of an UL-SCH transport block transmitted within a TTI Support for 64QAM in Uplink Maximum bit rate in Uplink (Mbps)
Category 1 5160 No 5
Category 2 25456 No 25
Category 3 51024 No 50
Category 4 51024 No 50
Category 5 75376 Yes 75

Refer to 3GPP 36.306 for other UE attributes.


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IMS registration sequence diagram

This sequence diagram details the message interactions involved in IMS registration. IMS registration from a visited IMS network is covered. The interactions covered are:

  • Terminal attaching to the GPRS Network.
  • Terminal activates a PDP context.
  • An unauthenticated IMS registration is attempted.
  • IPSec security association is established between the User terminal and the P-CSCF.
  • Finally the terminal performs an IPSec protected registration that completes the authentication of the network and the terminal.

IMS registration sequence diagram