Hello everyone, my name is Zsolt Krémer, I'm a
PhD student from the Budapest University of
Technology and Economics,
and I'm going to present our paper titled "Cooperative
Performance Enhancement Using Quick Tunneling in
5G Cellular Networks".
The other authors are Mirja Külavin, Markus Ilar
and Attila Mihály from Ericsson.
5G is going to bring very high peak data rates
and significantly lower latency,
however the propagation properties of the new
radio also result in higher volatility in
available bandwidth.
Previous studies showed that these factors intensify
the need for a shorter control loop and local
optimizations in the transport layer.
In LTE networks, this has been mostly achieved by
performance enhancing proxies, which basically
split the end-to-end connection into two separate
control loops for the two separate domains.
QUIC has recently been standardized as RFC 9000
and it is already widely deployed by Google.
It is expected that the traffic share of the
protocol is going to increase rapidly after the
standardization.
It's a fully encrypted transport protocol,
achieving an enhanced privacy for end-users.
However, this end-to-end encryption also makes
connection splitting solutions not feasible
anymore.
So a new approach is needed to enable network-assisted
performance optimization for encrypted protocols.
What we propose is a cooperative performance
enhancement framework,
using MASQ as the signaling protocol towards the
proxy, resulting in two layers of connections,
a QUIC tunnel between the client and the proxy,
and the end-to-end QUIC connection between the
client and the target application server.
It is important to note that the security context
of the end-to-end connection is unmodified,
so confidentiality, source authentication and
integrity is preserved.
Explicit consent is required for requesting a
service from the proxy.
And the separation of communication channel data
and tunnel data is possible by maintaining
separate QUIC streams in the same QUIC connection.
Overall, this design proves that it is possible
to provide proxy services without violating the
end-to-end principle of the transport and
application layers.
We have identified three different use cases,
based on a different granularity of cooperation
between the server, the client and the proxy,
and these are local loss recovery, promise
signaling and sending declarative messages to the
server.
When the client requests the local loss recovery
feature,
it is done by using the reliable data stream
service of the QUIC tunnel,
and besides this initial explicit request, no
additional signaling is needed.
Although packet losses are considered rare in 4G
and 5G networks when using acknowledged mode,
this use case can improve the performance of unacknowledged
mode as well, and thus enable lower latency.
On the right, you can see some preliminary
performance results using 1% emulated random loss,
and you can see that the average download time is
significantly lower when the local loss recovery
feature of the proxy is used,
especially if the RTT increases.
Promise signaling is useful if the bottleneck is
between the client and the proxy.
The proxy is able to send a so-called promise
signal, which indicates the reception of a packet
by the proxy,
and then the client can progressively acknowledge
these promised packets to the server.
So this allows the proxy to buffer a sufficient
number of packets,
and then quickly send them to the client if the
capacity increases.
This is similar to how split connection
performance enhancing proxies operate today.
The third use case is sending declarative
messages to the server.
This assumes another explicit tunnel between the
proxy and the server,
and then the proxy is able to send declarative "safe
to ignore" messages containing acknowledgement or
even NAC info,
and the server can then utilize these acknowledgements
and apply a multi-domain congestion control
algorithm,
which maintains two separate control loops for
the wired and the wireless domains.
One of them is clocked by the acknowledgements
from the proxy,
the other one clocked by the acknowledgements
from the client.
One of them can be more conservative and the
other one more aggressive,
and thus the algorithm is able to provide both
fairness in the wired domain and fast utilization
in the wireless domain.
On the right, there are some early results using
the millimeter wave module of the NS3 simulator,
and it can be seen that multi-domain congestion
control outperforms QUBIC significantly,
especially if the RTT of the internet link
increases,
with both using the CODEL AQM and the fixed 7MB
drop-tail buffer.
In conclusion, transparent connection-splitting
performance-enhancing proxies are not going to be
feasible for encrypted traffic.
We have proposed a cooperative performance-enhancing
framework based on the MASQ protocol,
built on explicit consensus by the endpoint,
and maintaining an unmodified security context of
the original end-to-end connection.
We have shown three different use cases, local
loss recovery, promise signaling, and declarative
messages to the server,
shown some promising early performance results,
and our future work mainly focuses on a detailed
performance evaluation in 4G and 5G network
conditions.
Thank you for your attention.