chunks: AIMD congestion control

refs #3636

Change-Id: Ia5e601201219048eb5c745bba9627e4916dac31a
diff --git a/tools/chunks/README.md b/tools/chunks/README.md
index 4fd607a..a3b05fd 100644
--- a/tools/chunks/README.md
+++ b/tools/chunks/README.md
@@ -11,13 +11,13 @@
   discovering the latest version of the file, and writes the content of the retrieved file to
   the standard output.
 
-## Version discovery methods
+## Version discovery methods in ndncatchunks
 
-* `fixed`    : ndncatchunks will send an interest attempting to find a data packet with the
+* `fixed`    : sends an interest attempting to find a data packet with the
                specified prefix and version number. A version component must be present at the
                end of the user-specified NDN name.
 
-* `iterative`: ndncatchunks will send a series of interests with ChildSelector set to prefer the
+* `iterative`: sends a series of interests with ChildSelector set to prefer the
                rightmost child and Exclude selectors, attempting to find a data packet with the
                specified prefix and the latest (the largest in the NDN canonical ordering)
                version number.  The version is declared "latest" after a predefined number of
@@ -25,6 +25,19 @@
 
 The default discovery method is `iterative`.
 
+## Interest pipeline types in ndncatchunks
+
+* `fixed`: maintains a fixed-size window of Interests in flight; the window size is configurable
+           via a command line option and defaults to 1.
+
+* `aimd` : sends Interests using an additive-increase/multiplicative-decrease (AIMD) algorithm to
+           control the window size. By default, a Conservative Loss Adaptation algorithm is adopted
+           combining with the AIMD algorithm, that is, at most one window decrease will be
+           performed per round-trip-time. For details please refer to:
+  [A Practical Congestion Control Scheme for Named Data
+  Networking](https://www.researchgate.net/publication/306259672_A_Practical_Congestion_Control_Scheme_for_Named_Data_Networking)
+
+The default Interest pipeline type is `fixed`.
 
 ## Usage examples