White Papers

Figure 2: Multi-prong latency model for AR Use Case Example
While the multi-prong model described above accommodates different round-
trip latency requirements for different use cases and their resulting workloads,
the I/O requirements introduced with services enabled by Scalable Edge Cloud
Compute further add to the constrained connectivity problem. The increasing
need to share context or transfer context to back-end processes in support of
having richer compute capability, coupled with the common desire to reduce
compute hardware at the end user device, increases bandwidth demands while
straining the ability to maintain low latency paths at every level in the hierarchy.
Therefore, the integration of the new emerging technologies and related,
increases requirements for both bandwidth and latency, while in turn enabling
the offloading compute needs at the end user.
Synchronization
A related requirement for real time streaming applications requiring higher
bandwidth and lower latency in a constrained environment, is the need to
synchronize the delivery of specific real time services within and between the
various transmission channels.
A few examples of these synchronization requirements and issues:
• Forward Channel transmissions (FC-FC): Audio-video-controller (AVC)
synchronization is required for normal video streaming, video
conferencing and interactive use cases such as gaming and AR/VR. In
cases with constrained or degraded connectivity, data may be lost,
delayed or received out of order at the end user, and need to be
reconstructed at the receiver.
• Forward Channel – Back Channel synchronization (FC-BC): In some
instances, forward channel information, such as IPC control information
may need to be sent, with the need to maintain synchronization with
position and motion tracking information being transmitted through the
back channel.
• Back Channel to Forward Channel (BC-FC): In some cases, such as
ultra-low latency closed loop processing, back channel information (e.g.
motion tracking in AR/VR or gaming environment) must stay in tight
loop synchronization with forward channel frame data. Any delay in
transmission may cause will cause dropped frames or incorrect post-
processing of frame data.