notes_slingshot-sigcomm23.pdf

Definitions:

• Baseband Signal: Original signal containing data

• Radio Signal: RF data where baseband signal is modulated to higher frequency levels for transmission

• BBU (Baseband Unit): responsible for processing baseband signals received from and transmitted to the user equipment through the radio units

• Fronthaul: segment of the network that connects the radio units to the centralized baseband units (BBUs) → links carry digitized radio signals between RUs and BBUs

  • usually require high bandwidth with low latency to meet real-time processing demands of the RAN

  • critical component that enables separation of RAN’s physical and network functions

    ⇒ separation allows for deployment of software-based BBUs on commodity hardware

• Backhaul: connection from base stations to the core network (involving higher capacity links like fiber or microwave) to carry aggregated data traffic

• vRAN (virtualized Radio Access Network): use software-based model to handle jobs done by RAN ⇒ consists of Virt

  • allow more flexibility depending on application
  • predict usage patterns by user equipments and control bandwidth

  ⇒ typical RANs with BBU cannot do this

• FAPI → protocol used when L1 and L2 layers are separate

Problems Nowadays:

1. Resilience to Fault - time between failure is very long
   1. repairs take several hours
   2. vRANs are particularly vulnerable to software crashes
2. Resilience to Planned Upgrades - significant user downtime in modern vRANs

Overview of Slingshot

→ short-term vRAN computation or I/O impairments during resilience are similar to routine wireless signal quality degradation