Host to modem interface
AssigneeItran Communications Ltd.
InventorsDan Raphaeli, Gonen Barkan
Life of this patent
Estimating the term…
Abstract
An apparatus for and a method of interfacing a host to a modem. Data is transferred between the host and the modem via a serial interface. The modem provides the physical layer implementation functions (i.e., transmission and reception functions) in addition to providing low level MAC layer function processing. Functions provided include collision detection, back-off algorithm according to a programmed back-off time, conditional transmission, automatic retransmissions and ACK/NACK packet generation and processing. This serves to eliminate any stringent access timing constraints usually placed on the host processor resulting in reduced cost and complexity of the host.
Claims24
A modem controller apparatus for use in a modem having a transmitter and a receiver, said modem coupled between a communications channel and a host, comprising:
- means for receiving transmit data and control data from said host wherein said transmit data is transmitted over said communications channel by said transmitter and said control data is used to configure and control the operation of said modem;
- means for receiving data transmitted over said communications channel from said receiver and for forwarding said receive data to said host;
- means for waiting an optional wait period before attempting transmission of a packet onto said channel;
- means for transmitting an optional preamble comprising at least one quiet period and the transmission of at least one predetermined symbol:
- back-off means for detecting the reception of a packet during one or more quiet periods of said preamble and aborting transmission if reception of a packet is detected;
- means for conveying first information comprising an indication of reception success or failure of the last packet received by said modem in a packet being transmitted;
- and
- means for declaring partial synchronization, including notification of said host that a synchronization event has occurred, upon detection of a fewer number of valid symbols than that required to achieve full synchronization, and wherein full synchronization is either reaffirmed or de-affirmed one or more additional symbol times in the future.
A modem apparatus coupled between a communications channel and a host, said host providing data and control packets to said modem, comprising:
- a transmitter for transmitting transmit data over said communications channel;
- a receiver for receiving data transmitted over said communications channel;
- detection means for detecting the reception of a packet after said host sends transmit data to said modem but before the actual transmission of data over said communications channel;
- and
- a modem controller operative to:
- receive transmit data and control data from said host;
- forward said transmit data to said transmitter for transmission over said communications channel;
- configure and control the operation of said modem in accordance with said control data;
- receive data transmitted over said communications channel from said receiver;
- forward said received data to said host;
- in response to receipt of a packet by said detection means, cause said modem to switch from a transmit mode to a receive mode without any intervention of said host and for notifying said host that the current transmission attempt is to be aborted;
- and
- declare partial synchronization, including notifying said host that a synchronization event has occurred, upon detection of a fewer number of valid symbols than that required to achieve full synchronization, and wherein full synchronization is either reaffirmed or de-affirmed one or more additional symbol times in the future.
A method for controlling low level access in a modem apparatus having a transmitter and a receiver, said modem coupled between a communications channel and a host, said method comprising:
- receiving transmit data and control data from said host wherein said transmit data is transmitted over said communications channel by said transmitter and said control data is used to configure and control the operation of said modem;
- receiving data transmitted over said communications channel from said receiver and forwarding said receive data to said host;
- waiting an optional wait period before attempting transmission of a packet onto said communications channel;
- transmitting an optional preamble comprising at least one quiet period and the transmission of at least one predetermined symbol;
- detecting the reception of a packet during one or more quiet periods of said preamble;
- aborting transmission of the current packet if reception of a packet is detected;
- conveying information about the last packet received by said modem in a packet being transmitted;
- and
- declaring partial synchronization, including notification of said host that a synchronization event has occurred, upon detection of a fewer number of valid symbols than that required to achieve full synchronization, and wherein full synchronization is either reaffirmed or de-affirmed one or more additional symbol times in the future.
Dependencies are inferred from the claim text.