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来自「用C++编写的GPRS协议栈源代码」· HTML 代码 · 共 58 行
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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"><!--Converted with LaTeX2HTML 96.1 (Feb 5, 1996) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds --><HTML><HEAD><TITLE>Link Layer(LL)</TITLE><META NAME="description" CONTENT="Link Layer(LL)"><META NAME="keywords" CONTENT="gprs"><META NAME="resource-type" CONTENT="document"><META NAME="distribution" CONTENT="global"><LINK REL=STYLESHEET HREF="gprs.css"></HEAD><BODY LANG="EN"> <A NAME="tex2html516" HREF="node40.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="http://cbl.leeds.ac.uk/nikos/figs/next_motif.gif"></A> <A NAME="tex2html514" HREF="node1.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="http://cbl.leeds.ac.uk/nikos/figs/up_motif.gif"></A> <A NAME="tex2html508" HREF="node38.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="http://cbl.leeds.ac.uk/nikos/figs/previous_motif.gif"></A> <BR><B> Next:</B> <A NAME="tex2html517" HREF="node40.html">LL class in C++</A><B>Up:</B> <A NAME="tex2html515" HREF="node1.html">The General Packet Radio </A><B> Previous:</B> <A NAME="tex2html509" HREF="node38.html">To bypass the RLC</A><BR> <P><H1><A NAME="SECTION00150000000000000000">Link Layer(LL)</A></H1><P> This describes an implementation of Link Layer which supports fragmentationand link level ARQ<A NAME="tex2html3" HREF="footnode.html#281"><IMG ALIGN=BOTTOM ALT="gif" SRC="http://cbl.leeds.ac.uk/nikos/figs/foot_motif.gif"></A> . Though this was written as a part of GPRS stackimplementation, it can be used independently with any other stack with minormodifications(section 4).<P>The default LL provided by ns has been modified to include fragmentation andacknowledged mode as options. In acked mode, currently only one MS canbe supported.<P>The LL can be used in fragmented or unfragmented mode. This can beconfigured from the OTcl script. In fragmented mode, packets received fromthe sending Agent are segmented before sending down to the RLC and arereassembled at the other end, before being passed up to the receiving Agent.The fragment size can be set by the user. It is currently set at a defaultof 1500 bytes in accordance with themaximum LL PDU size specified in GPRS.<P>The LL can be used in acked or unacked mode. A stop-and-wait retransmitmechanism is implemented. The LL header has been modified to accommodatethese changes. Presently, this implementation supports only 2 nodes in theacked mode.<P>In unacked mode with no fragmentation, the Link Layer functions like thedefault <I>ns</I> Link Layer.<P><BR> <HR><UL> <LI> <A NAME="tex2html518" HREF="node40.html#SECTION00151000000000000000">LL class in C++</A><LI> <A NAME="tex2html519" HREF="node41.html#SECTION00152000000000000000">Parameters</A><LI> <A NAME="tex2html520" HREF="node42.html#SECTION00153000000000000000">Modifications for use outside GPRS/GSM</A></UL><BR> <HR><P><ADDRESS><I>Richa Jain (96D07007) <BR>Tue Jul 24 22:29:53 IST 2001</I></ADDRESS></BODY></HTML>⌨️ 快捷键说明
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