Meshdynamics
Efficient Voice over Internet Protocol (VoIP) on Mesh Networks
      Mobile Military communications Tested VOIP Communications with SIP phones MeshDynamics VOIP test in underground mine  
Overview:

Meshdynamics multi-radio multi-channel backhaul ensures deterministic latency and jitter by eliminating both the effects of single radio backhauls and involuntary contention. Besides the inherently high performance of Meshdynamics' patented multi-radio backhaul technology, additional specialized voice features minimize delay and jitter.

These features insure that voice is transported rapidly and efficiently across the network, maximizing the number of voice calls that may be supported while minimizing wasted bandwidth.  Meshdynamics multi-radio multi-channel backhaul ensures deterministic latency and jitter by eliminating both the effects of single radio backhauls and involuntary contention. 

Extensions for near isochronous M2M messaging is discussed. This is relevant to the Mesh Node Application Layer.
 
Latency/Jitter Degradation on Single Channel Backhauls

Latency is inversely related to available bandwidth: thin pipes can provide only so much flow. Single channel backhauls suffering from bandwidth degradation also suffer from poor latency and jitter over multiple hops. This is primarily due to the need for a single radio to serve both backhaul and client traffic. The result is that most First Generation single-channel backhaul networks provide reliable video- or voice service over only one- or two hops. As a result many more costly wired or fiber Internet or intranet drops are needed to deliver adequate service, increasing the ongoing total cost of ownership.
 
Third Generation mesh products do not suffer from bandwidth degradation – they use multiple backhaul radios to obviate radio channel interference. Field tests indicate a latency of less than 1 millisecond per hop even under heavy traffic. Since latency is thus not a factor of traffic or user density, jitter (variation in delay) is also very low. This makes Third Generation products suitable for networks serving large number of users, demanding applications, video, and voice -- even simultaneously.

Meshdynamics patented multi-radio multi-channel backhaul ensures deterministic latency and jitter by eliminating both the bandwidth degradation effects of single radio backhauls and involuntary contention in multi-hop networks.

Real Time Packet Delivery Services optimized for Small Packets

Additionally, Meshdynamics multi-radio backhauls also incorporate VOIP concatenation for timely VOIP packet delivery. VOIP packets are small – typically less than 300 bytes but sent frequently, generally once every 20 milliseconds. Networking protocols like CSMA/CA don’t transport small and time sensitive packets well. The VOIP concatenation engine aggregates small VOIP packets into a larger packet for more efficient delivery. This aggregation takes place every 5-10 milliseconds. USAF tests show overall latency is less than 10 ms + 1 ms per hop over a 4 hop network. Jitter is less than 1 ms. per hop.
 

Figure 1a (left): Latency for 36 simultaneous VOIP calls over a 4 hop Mesh running VOIP Concatenation over the backhaul.
Figure 1b (right): Jitter for 36 simultaneous VOIP calls over a 4 hop Mesh running VOIP Concatenation over the backhaul.

Persistent Base VoiceTM (PBV)

Applications, like Persistent Base VoiceTM (PBV) become feasible. when  deterministic latency and jitter is assured. With PBV, VOIP phones can function even when the SIP gateway is not reachable: the mesh nodes act as a temporary proxy SIP server till nodes rejoin the main mesh.  Beyond sharing SIP registries between previously isolated network clusters, applications like PBV need  accurate estimates of when small packet deliveries occur. If  the bulk container shuttle bus schedule is inappropriately timed, it will periodically miss small packet "herds" that arrive around the same time. Schedules are monitored and dynamically revised.

Please also see  Press Release    Illustration     Patent

Application Extensions For Industrial Internet of Things (IIOT)

With deterministic jitter and latency in place, accurate estimates are computed on the "round trip" delay from wireless end devices to cloud and back. This information, computed periodically, is available to applications resident on the mesh nodes. Machine to Machine  (M2M) communications -- like VOIP packets-- are typically terse and preferably isochronous. Applications access current jitter and latency from source to destination, for different clients on the mesh network -- each with their own sender-receiver transmission routes -- and then determine the best bus shuttle service and schedule for VOIP concatenation based routing.

Please see The Abstracted Network for Enterprises and the Internet of Things. for more.

Related to VOIP Concatenation Engine

1. Meshdynamics receives Prestigious VIEW certification Certification received from Spectralink/Polycom
2. Meshdynamics First With Persistent Voice Over Wireless Mesh VOIP calls work even when no SIP server is present. 
3.   Meshdynamics Delivers Persistent Wi-Fi Network for Mobile Environments  Merging and dispersal in mobile networks
4. Wi-Fi based Femtocell Extensions for the outdoor enterprise. Extension of Femtocell coverage using mesh.
5. VOIP and VIDEO on a City wide scale Meshdynamics VOIP Concatenation Engine explained.