Ultra-reliable low latency communication (URLLC) aims to provide extremely reliable communication with very low latency for mission-critical applications. URLLC requires block error rates as low as 10^-9 and latencies in the order of milliseconds. Sources of delay and packet loss include transmission errors, coding delay, computing delay, propagation delay, backhaul delay, and transmission queueing violations. URLLC supports both scheduled and non-scheduled traffic using techniques like grant-free access, k-repetitions, and co-existence with enhanced mobile broadband scheduling through instant and reservation-based scheduling algorithms. Resource allocation problems can be modeled as knapsack problems to optimize metrics like throughput under constraints like available resource blocks.

1. URLLC
Ultra-reliable low latency communication

2. URLLC (Ultra-reliable low latency
communication)
• Ultra Reliable → BLERs as low as 10^-9 (10^-5 on [ITU-R M.2410.0])
• Ultra Low Latency →Very low latency
• Relate to mission-critical applications, where interrupted and robust exchange of
data is of outmost importance.

3. uRLLC Use Case

5. Source of Delay
• transmission delay
• coding delay
• computing delay
• propagation delay
• backhaul delay
• DL transmission delay

6. Source of Packet Loss
• transmission error -> depends on resource allocation
• queueing delay violation

7. Scheduled/Non-ScheduledTraffic
• Scheduled traffic
• Non-scheduled traffic
• Connected/disconnected devices that have critical data, usually have short payload size
• Devices that request access reservation for subsequent scheduled transmissions of
critical data
• Critical device-to-device communications
• Effect of non-scheduled traffic:
• Queuing delay violation for scheduled traffic
• Delay and packet error probability for the first transmission

8. URLLC SCHEDULING

9. Grant-FreeAccess
Removing phases of scheduling request and grant issuing
Conventional Grant-Free

10. K-Repetitions
• Repeating the transmission multiple time
• When the first connection is “broken” the second one could replace, and so on.

12. CO-EXISTENCEWITH
EMBB SCHEDULING

13. Co-Existence with eMBB Schedulling
• Why it’s important? uRLLC traffic could be bursting,
• Types of scheduling:
• Instant Scheduling
• Ongoing transmission interrupted
• (-) Performance Degradation on the other transmission
• (+)outperform the reservation based
• Reservation Based Scheduling
• Resource are reserved before
• Types:
• Semi-static
• Dynamic

14. SCHEDULING
ALGORITHMS
+ Comp Sci Algorithms Related to Scheduling and Resource

16. Greedy algorithms
• Find local optimum in intent to find global optimum solution
• Example in Scheduling:
• Select user with largest RB to scheduled first, then the rest filled in the rest. Until the
queue is empty. → Goal: OptimizeThroughput
• Select users with best Signal Strength to scheduled first. → Goal: maintain reliability

17. Knapsack
• Given a set of items, each with a
weight and a value, determine the
number of each item to include in a
collection so that the total weight
is less than or equal to a given limit
and the total value is as large as
possible.
• Example:
• Weight: Resource Block (RB)
• Value:Throughput
Optimize Knapsack is NP-Hard (Nondeterministic
Polynomial time to solve) or we can say better to
guess the solution. Greedy is one of the solution.