In the mobile optimization landscape, session optimization is one technology in an operator's tool box to assist in the struggle to contend with network congestion (other tools include content-based optimization techniques focused on reducing mobile data traffic traversing the RAN).
There is general understanding that the relationship between IP session control, most notably TCP, and mobile networks is a love and hate relationship. TCP does an admirable job of managing congestion, efficiently servicing the subscriber, and reacting to changes in the network on the scale of the whole worldwide Internet. TCP works best in low latency, low jitter, low congestion, and low packet loss environments. However, all of these characteristics are highly variable in the mobile network depending on weather, user device power levels, interference (buildings, vehicles, hills...), network loading, number of subscribers, and types of applications being accessed by subscribers, all of which can severely impact TCP performance. What mobile session optimization products attempt is to "tweak" the session control protocols and algorithms to make TCP applications think that they are operating in a pristine network environment, promising improvements in the subscriber's user experience, including:
- Higher effective throughput (faster downloads, streaming video, higher performance gaming...)
- Faster session setup
- Less user impact from changing network conditions
In deploying session optimization solutions, operators hope to achieve:
- Better user experience, less churn, less customer satisfaction issues
- Reduced air interface "chatter" by reducing the ping-pong interactions of TCP clients and servers
- More efficient use of radio and network bandwidth
So it is clear that session optimization is one tool to help improve customer experience and to make mobile networks more efficient. However, several implications need to be considered:
- Session optimization solutions generally require client software to be installed on the mobile devices. This is an operational and customer challenge which limits the number of devices that actually support session optimization.
- Session optimization requires dedicated resources in the mobile core that must scale to 10,000s to 100,000s of concurrent sessions with attendant cost, performance, reliability, and operational impacts to the mobile network.
- Since session optimization "tweaks" traditional session control, there are conditions whereby the optimization can increase the congestion and degrade user experience when there is very high traffic or unusual network conditions.
- Session optimization minimally reduces the amount of traffic, so it does not directly impact the constraint of limited radio and backhaul bandwidth, and therefore does not change the economics of delivering mobile broadband.
To better control traffic growth, mobile operators need to explore a range of optimization solutions and focus on those that provide the best results both in performance and economics. Session optimization is just one of the potential technologies along with RAN content optimization and others.