edit; incorporate comments from todays meeting

diff --git a/doc/txt/tep124.txt b/doc/txt/tep124.txt
index d4d8c94d23000115fc32c7b8434373326b0a2759..0e8c24137fc3789f8f7c25e34c1d888f938cb317 100644 (file)
--- a/doc/txt/tep124.txt
+++ b/doc/txt/tep124.txt
@@ -1,8 +1,8 @@
 ============================
 ============================

-Link Quality Exchange Protocol (LQEP)
+The Link Estimation Exchange Protocol (LEEP)

 ============================
 
 ============================
 

-:TEP: 114 
+:TEP: 124 

 :Group: Network Protocol Working Group 
 :Type: Documentary
 :Status: Draft
 :Group: Network Protocol Working Group 
 :Type: Documentary
 :Status: Draft


@@ -24,9 +24,9 @@ Link Quality Exchange Protocol (LQEP)
 Abstract
 ============================================================================
 
 Abstract
 ============================================================================
 

-The memo documents the Link Quality Exchange Protocol (LQEP). Nodes
-use LQEP to exchange information about the quality of links to the
-neighbors.
+The memo documents the Link Estimation Exchange Protocol (LEEP). Nodes
+use LEEP to estimate and exchange information about the quality of
+links to the neighbors.

 
 1. Introduction
 ============================================================================
 
 1. Introduction
 ============================================================================


@@ -35,7 +35,7 @@ Routing protocols often require bi-directional link qualities to
 compute the routes. Nodes can estimate the quality of the in-bound
 link from a neighbor by estimating the ratio of successfully received
 messages and the total transmitted messages. These in-bound link
 compute the routes. Nodes can estimate the quality of the in-bound
 link from a neighbor by estimating the ratio of successfully received
 messages and the total transmitted messages. These in-bound link

-qualities are exchanged among the neighbors using LQEP to determine
+qualities are exchanged among the neighbors using LEEP to determine

 the out-bound link qualities. Bi-directional link quality is computed
 using thus learned in-bound and out-bound link qualities.
 
 the out-bound link qualities. Bi-directional link quality is computed
 using thus learned in-bound and out-bound link qualities.
 


@@ -47,17 +47,18 @@ using thus learned in-bound and out-bound link qualities.
 
 Quality of the link between any two nodes describes the probability
 with which data link layer packets can be received without any
 
 Quality of the link between any two nodes describes the probability
 with which data link layer packets can be received without any

-error. The link between the nodes A and B may have different quality
-in A to B and B to A directions.
+error. This definition assumes uncorrelated link losses. The link
+between the nodes A and B may have different quality in A to B and B
+to A directions.

 
 2.2 In-bound Link Quality
 --------------------------------------------------------------------
 
 In a node pair (A,B), with B as the node of reference, in-bound link
 
 2.2 In-bound Link Quality
 --------------------------------------------------------------------
 
 In a node pair (A,B), with B as the node of reference, in-bound link

-quality is defined as a value ranging from 0 to 255 that describes the
-quality of the link from A to B estimated by B by counting the
-successfully received packets from A among all the transmitted packets
-or using link quality indicators (LQI,RSSI) provided by the radio on
+quality is a value in the range of 0 to 255 that describes the quality
+of the link from A to B estimated by B by counting the successfully
+received packets from A among all the transmitted packets or using
+link quality indicators such as LQI and RSSI provided by the radio on

 the node B, or some other methods.
 
 2.3 Out-bound Link Quality
 the node B, or some other methods.
 
 2.3 Out-bound Link Quality


@@ -66,56 +67,62 @@ the node B, or some other methods.
 In a node pair (A,B), with B as the node of reference, out-bound link
 quality is defined as the quality of the link from B to A. B can
 determine the out-bound link quality if A advertises its in-bound link
 In a node pair (A,B), with B as the node of reference, out-bound link
 quality is defined as the quality of the link from B to A. B can
 determine the out-bound link quality if A advertises its in-bound link

-qualities. LQEP is the protocol that is used to exchange the in-bound
+qualities. LEEP is the protocol that is used to exchange the in-bound

 link qualities.
 
 2.4 Link Information Entry
 --------------------------------------------------------------------
 
 link qualities.
 
 2.4 Link Information Entry
 --------------------------------------------------------------------
 

-Link Information Entry is a tuple (n,q) where q is the in-bound link
-quality from the node n.
+Link Information Entry created by node k is a tuple (n,q) where q is
+the in-bound link quality from node n to k.

 
 

-2. Link Quality Exchange Protocol (LQEP)
+3. The Link Estimation Exchange Protocol (LEEP)

 ============================================================================
 
 ============================================================================
 

-2.1 Assumptions
+3.1 Assumptions

 --------------------------------------------------------------------
 
 --------------------------------------------------------------------
 

-Following are the assumptions made by LQEP:
+Following are the assumptions made by LEEP:

 
 

-2.1.1. The data link frame has a single-hop source field.
-2.1.2. The data link layer provides a broadcast address.
-2.1.3. The data link layer provides the length of the LQEP frame.
+3.1.1. The data link frame has a single-hop source field.
+3.1.2. The data link layer provides a broadcast address.
+3.1.3. The data link layer provides the length of the LEEP frame.

 
 

-2.2 The Protocol
+3.2 The Protocol

 --------------------------------------------------------------------
 
 To compute the bi-directional link quality, in-bound link quality must
 --------------------------------------------------------------------
 
 To compute the bi-directional link quality, in-bound link quality must

-be exchanged among the neighbors. LQEP maintains a sequence number
-that is incremented by one for each outgoing LQEP frame. LQEP frame
-transmits this sequence number and Link Information entries describing
-the in-bound link qualities for a subset of its neighbors. When a node
-receives the LQEP frame and finds its node id in one of the Link
-Information entries, the node MUST use the second element of that
-tuple as its out-bound link quality to the neighbor identified by the
-data link source address. The LQEP sequence number SHOULD be used to
-estimate the in-bound link quality.
-
-2.3 LQEP Frame
+be exchanged among the neighbors. LEEP maintains a sequence number
+that is incremented by one for each outgoing LEEP frame. The sequence
+number in the LEEP frame MUST be incremented by one even if the data
+link layer retransmits the LEEP frame. The LEEP sequence number MAY be
+used to count the number of missing packets to estimate the in-bound
+link quality from the transmitter. LEEP MUST transmit Link Information
+entries describing the in-bound link qualities for a subset of its
+neighbors. The Link Information entry on the LEEP frame allows the
+receiver node to find the out-bound link quality to the transmitter
+node identified by the data link source address.
+
+3.3 LEEP Frame

 --------------------------------------------------------------------
 
 --------------------------------------------------------------------
 

-A LQEP frame has a header, the payload, and a footer with the Link
+A LEEP frame has a header, the payload, and a footer with the Link

 Information (LI) entries as shown in this diagram:
 
   -------------------------------------------------------------
 Information (LI) entries as shown in this diagram:
 
   -------------------------------------------------------------

-  |   LQEP   | Payload | LI Entry | LI Entry | ... | LI Entry |
+  |   LEEP   | Payload | LI Entry | LI Entry | ... | LI Entry |

   |  Header  |         |     1    |     2    |     |     n    |
   -------------------------------------------------------------
 
   |  Header  |         |     1    |     2    |     |     n    |
   -------------------------------------------------------------
 

+The number of Link Information entries can be different in each
+outgoing LEEP frame. The number of Link Information entries MUST not
+increase the size of the LEEP frame beyond the maximum payload length
+allowed by the data link layer. A LEEP frame can have 0 Link
+Information entry.

 
 

-2.3.1 LQEP header
+3.3.1 LEEP header

 
 

-The following diagram shows the LQEP header format:
+The following diagram shows the LEEP header format:

                            1
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                            1
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


@@ -126,11 +133,11 @@ The following diagram shows the LQEP header format:
 Field definitions:
 
 nentry - Number of Link Information entries in the footer
 Field definitions:
 
 nentry - Number of Link Information entries in the footer

-seqno - LQEP sequence number.
-rsrvd - Reserved
+seqno - LEEP sequence number.
+rsrvd - Reserved and must be set to 0.

 
 
 
 

-2.3.2 Link Information Entry
+3.3.2 Link Information Entry

 
 The following diagram shows the Link Information Entry format:
                            1
 
 The following diagram shows the Link Information Entry format:
                            1


@@ -145,25 +152,28 @@ Field definitions:
 
 node id: the link layer address of the neighbor
 link quality: The in-bound link quality from the node identified by node id
 
 node id: the link layer address of the neighbor
 link quality: The in-bound link quality from the node identified by node id

+   to the node that transmits this Link Information entry

 
 
 
 

-7. Implementation
+4. Implementation

 ============================================================================
 
 ============================================================================
 

-The following files in ``tinyos-2.x/tos/lib/net/le`` provide a reference 
-implementation of LQEP described in this TEP.
+The following files in ``tinyos-2.x/tos/lib/net/le`` provide a
+reference implementation of LEEP described in this TEP.

 
 

-  * ``LinkEstimator.h`` and ``LinkEstimatorP``
+  * ``LinkEstimator.h`` and ``LinkEstimatorP.nc``

 
 

-The reference implementation uses the LQEP sequence number to estimate
-the in-bound link quality. The implementation tries to append Link
-Information entry for all the neighbors in its neighbor table by
-sending the largest possible data link frame. If there is still not
-enough room to fit all the Link Information entries, it uses a
-round-robin policy to select the entries to be exchanged that could
-not fit in the previous LQEP frame.
+The reference implementation uses the LEEP sequence number to count
+the number of missing packets to estimate the in-bound link
+quality. The implementation tries to append Link Information entry for
+all the neighbors in its neighbor table by sending the largest
+possible data link frame. If there is still not enough room to fit all
+the Link Information entries, it uses a round-robin policy to select
+the entries to be exchanged that could not fit in the previous LEEP
+frame. The LEEP frames are transmitted whenever the CTP [1]_ beacons,
+sent as a LEEP payload, are sent.

 
 

-8. Author's Address
+5. Author's Address

 ============================================================================
 
 | Omprakash Gnawali
 ============================================================================
 
 | Omprakash Gnawali


@@ -175,3 +185,7 @@ not fit in the previous LQEP frame.
 | email - gnawali@usc.edu
 |
 
 | email - gnawali@usc.edu
 |
 

+6. Citations
+============================================================================
+
+.. [1] TEP 123: The Collection Tree Protocol.