Tidy up

docs/lectures/acn/06_DTN_congestion_control.md

@@ -1,28 +1,28 @@
 # Framework for Congestion Control in Delay Tolerant Opportunistic Networks
 
-DTNs mainly focus on increasing the probability to deliver to the destination and on minimising delays
+DTNs mainly focus on increasing the probability of delivery to the destination and on minimising delays.
 
-* Using complex graph theory techniques
-* Where load is unfairly distributed towards the better connected nodes
-* May lead to network congestion
+- Using complex graph theory techniques
+- Where load is unfairly distributed towards the better connected nodes
+- May lead to network congestion
 
 ## CAFREP
 
 CAFREP or Congestion Aware Forwarding and Replication
 
-* Detects the congested nodes and parts of the network
-* Moves the traffic away from hot-spots and spreads it around while preserving the directionality of the traffic and not overwhelming non-interested nodes with unwanted content
-* Adaptively change message replication rates
+- Detects the congested nodes and parts of the network
+- Moves the traffic away from hot-spots and spreads it around while preserving the directionality of the traffic and not overwhelming non-interested nodes with unwanted content
+- Adaptively changes message replication rates
 
 When deciding on the best carrier and the optimal number of messages, CAFREP dynamically combines three heuristics
 
 1. **Contact** analytics
 2. Predictive **node congestion** (node storage and in-network delays)
-3. Predictive **ego network congestion** 
+3. Predictive **ego network congestion**
 
 ![img](img/g.png)
 
-Each layer you go up, the more information is exchanged between the nodes.
+As you move up each layer, more information is exchanged between the nodes.
 
 ### Metrics
 
@@ -34,43 +34,43 @@ $$
 Ret(X) = B_c(X) - \sum^N_{i=1} \space M^i_{size}(X)
 $$
 
-For a node $X$, it has buffer of size $B_c(X)$. When a message of size $M^i_{size}$ is sent to node $X$, it's buffer size is the total buffer minus the memory taken by the sum of all messages in the buffer.
+Node $X$ has a buffer of size $B_c(X)$. When a message of size $M^i_{size}$ is sent to node $X$, its available buffer size is the total buffer minus the memory taken by the sum of all messages in the buffer.
 
 ###### Node Receptiveness
 
-- Aims to avoid or decrease sending rates to the **nodes** that have higher in network delays
+- Aims to avoid or decrease sending rates to the **nodes** that have higher in-network delays
 
 $$
 Rec(X) = \sum^N_{i=1}(T_{now} - M^i_{received}(X))
 $$
 
-How long a node keeps a message before forwarding it on. If a high level of receptiveness is found on a node, it means the node isn't useful as messages aren't forwarded. Could mean the node has limited connections.
+How long a node keeps a message before forwarding it on. If a high level of receptiveness is found on a node, it means the node isn't useful as messages aren't forwarded. This could mean the node has limited connections.
 
 ###### Node Congestion Rate
 
-- Aims to avoid or decrease sending rates to **nodes** that congest at the higher rate
+- Aims to avoid or decrease sending rates to **nodes** that become congested at a higher rate
 
 $$
 CR(X) = \frac{100\cdot T_{FullBuffer}(X)/T_{TotalTime}(X)}{\frac{1}{N}\cdot \sum^N_{i=1}(T_iend(X) - T_istart(X))}
 $$
 
-Estimates the time between a node being full and full again. Measures the time the node is unusable.
+Estimates the time between a node being full and becoming full again. Measures the time the node is unusable.
 
 #### Ego Network Congestion Metrics
 
 ###### Ego Network Retentiveness
 
-* Aims to replicate less at the **parts of the network** with lower buffer availability.
+- Aims to replicate less at the **parts of the network** with lower buffer availability.
 
 $$
 EN_{Ret}(X) = \frac{1}{N}\sum^N_{i=1}Ret(C_i(X))
 $$
 
-Gets the average of the retentiveness of node $X$ and it's neighbours $c_i(X)$
+Gets the average retentiveness of node $X$ and its neighbours $c_i(X)$.
 
 ###### Ego Network Receptiveness
 
-* Aims to replicate less at **parts of the network** with higher delays.
+- Aims to replicate less at **parts of the network** with higher delays.
 
 $$
 EN_{Rec}(X) = \frac{1}{N}\sum^N_{i=1}Rec(c_i(X))
@@ -79,7 +79,7 @@ $$
 ###### Ego Network Congestion Rate
 
 - Aims to send less to the **parts of the network** that have higher congestion rates.
-- This is useful as if a node isn't congested, but all connected nodes are. It stops it from being used.
+- This is useful if a node isn't congested but all connected nodes are. It stops the node from being used.
 
 $$
 EN_{CR}(X) = \frac{1}{N}\sum^N_{i=1}CR_i(X)
@@ -93,6 +93,6 @@ $$
 Replication\space rate = M \times \frac{TotalUtil(Y)}{TotalUtil(X) + TotalUtil(Y)}
 $$
 
-Total utility, changes constantly. The replication limit grows to take advantage of all available resources, and backs off when congestion increases.
+Total utility changes constantly. The replication limit grows to take advantage of all available resources and backs off when congestion increases.
 
 Social utility prevents replication at a high rate on free nodes that are not on the path to the destination.