Quartz 4

quality of service

3 min read

private5G

vs network slicing

  • a rule-based system → prioritizes certain traffic flows (likea voice call or live stream) over others on a shared network infra → assigns a priority ID (like a 5QI in 5G) → determine who goes first when the network is busy
  • all traffic shares same traffic → performance can degrade severly during heavy congestion → a surge from one large user can slow down everyone else

quality of service in wireless networks, slicing, private 5G

approaches

  • over-provision resources
  • allocate resources, QoS-aware

circuit switching

QoS in 802.11

qos sensitive but no guarantees

sensitivity: 3 bit field QoS added to frames (in 802.11 frame, qos takes up 2 bytes)

  • higher priority frames ⇒ MAC scheduled at a given node before lower prority frames
  • CSMA mechanism generalized ⇒ higher priority frames awaiting transmission acoss wlan statistically more likely to be transmitte dthan lower priority frames

8 level of priorities for 802.11

end-end QoS sensitivity:

  • end-end netowrk layer QoS (differentiated services) ⇒ maps to local WLAN QoS

CSMA

wifi through tifi 6: qos sensitive but no guarantees (soft, hard) wifi 7: 4g/5g:

  • no specific admission decision policies standardized
  • lots of qos mechanism

QoS in 5G

  • QoS flow: unit of QoS in 5G
    • each flow carries a UE’s packets with same QoS requirements
    • 2 types of flows:
      • guaranteed bit rate
      • non-guaranteed bit rate
    • flow’s QoS requirements specified by 5QI (5G QoS identifier)

hard sharing: each UE gets dedicated
vs statistical sharing: each UE uses shared link bandwidth as needed (no hard allocation)

SLA: service level agreement btw physical resource owner/operator and “user” quantifies rsource requirements (traffic, computational loads) and extent of permissible queueing, delays, non-availability of resources

5QI

  • aka 5G QoS identifier → scalar value in 5g → pointer to specific QoS characteristics (priority, packet delay budget, error rates) → how data packets are handled
  • 5QI table mapping: standardized 5QI values (80,82,84) → maps to distinct performance targets including 5ms to 30ms packet delay budgets

traffic policing ⇒ limits traffic to not exceed declared parameters

  • long term average rate: # of packets can be sent per unit time in the long run
  • peak rate:
  • burst size: max # of packets sent consecutively with no intervening idle

policing mechanism: ⇒ limit number of packet arrivals to an average arrival rate and burstiness

  • leaky bucket policer

slicing, virtualization in 5G

slicing ⇒ enables multiple independent logical (virtual) 5G networks to operate simultaneously using the same physical network infra

  • ?????????????? why not concrete?
  • oversubscription example

traffic policing

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