Browse Prior Art Database

FLOW CONTROL INTEGRATION IN LAPI ESTABLISHED STATE

IP.com Disclosure Number: IPCOM000008670D
Original Publication Date: 1998-Jun-01
Included in the Prior Art Database: 2002-Jul-02
Document File: 2 page(s) / 80K

Publishing Venue

Motorola

Related People

Keith Parmer: AUTHOR [+2]

Abstract

Link Access Protocol-iDEN (LAPi) is a layer 2 protocol connecting the Fixed Network Equipment (FNE) and the Mobile Stations (MS) in an iDEN (Integrated Dispatch Enhanced Network) cell. LAPi provides point-to-point, packet-switched, reliable connection-mode service on a multiple-access channel.

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MOTOROLA Technical Developments

FLOW CONTROL INTEGRATION IN LAPI ESTABLISHED STATE

by Keith Parmer and Tim Spets

  Link Access Protocol-iDEN (LAPi) is a layer 2 protocol connecting the Fixed Network Equipment (FNE) and the Mobile Stations (MS) in an iDEN (Integrated Dispatch Enhanced Network) cell. LAPi provides point-to-point, packet-switched, reliable connection-mode service on a multiple-access channel.

  In LAPi, flow control is initiated when a receiver runs low on buffers. This is accomplished by sending a Receiver Not Ready (RNR) message to the trans- mitter. Upon receiving the RNR, the transmitter will stop sending data messages, which are called IPDUs, until a Receiver Ready (RR) message is received. Control messages can still be exchanged

after receiving an RNR. Since there is considerable delay in the system, RNR messages are sent before all buffers are exhausted. This allows the receiver to receive messages that were "in the pipe" when it entered flow control. IPDUs are acknowledged with STAT PDUs. IsRR (Is your Receiver Ready) messages are periodically sent when the transmitter has data to send, but an RNR has been received. This provides a recovery mechanism for a lost RR.

  The problem with this method is that there is no mechanism for recovery if the RNR is lost as shown in Figure I: Current LAPi Flow Control.

MS LAPi FNE LAPi

Data l

IPDU

STAT

l

Data b

FNE enters flow control

RNR

The RNR is lost

Data l

Data c

IPDU

STAT

Data b

FNE runs out of buffers...