Wireless Mantra of the Week: 5G QoS

Mantra: 5G defines more comprehensive QoS compared to LTE to enable realization of highly diverse services.
Brief Explanation. The basic granularity of QoS control in 5G is a QoS Flow. A QoS Flow could be Guaranteed Bit Rate (GBR) or non-GBR. A special type of a new GBR bearer in 5G is delay-critical GBR. A QoS Flow exists between the UE and the UPF for a given PDU session associated with a Network Slice. A QoS Flow is assigned 5G QoS Identifier (5QI), Allocation and Retention Priority (ARP), and GBR/non-GBR bearer-specific parameters. 5QI is analogous to QCI in LTE and automatically defines parameters such as the bearer type, the packet delay budget specifying the UE-UPF latency, packet error rate, scheduling priority, maximum data burst volume (amount of data served within the packet delay budget), and averaging time window for bit rate calculations. ARP, as in LTE, influences priority and preemption. A new non-GBR bearer parameter is Reflective QoS Attribute that indicates if the uplink QoS is the same as the downlink QoS. GBR bearer parameters include Guaranteed Flow Bit Rate, Maximum Flow Bit Rate, Maximum Packet Loss Rate, and Notification Control (to convey if a data rate can be guaranteed or not).

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