Electrical computers and digital processing systems: multicomput – Computer-to-computer protocol implementing – Computer-to-computer data streaming
Reexamination Certificate
2000-08-23
2004-07-13
Cardone, Jason D. (Department: 2142)
Electrical computers and digital processing systems: multicomput
Computer-to-computer protocol implementing
Computer-to-computer data streaming
C709S228000, C710S019000, C725S078000
Reexamination Certificate
active
06763391
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of managing the transmission of data between devices. More particularly, the present invention relates to the field of managing allocation of resources and bandwidth capabilities during the transmission of data between devices.
BACKGROUND OF THE INVENTION
The IEEE standard, “IEEE 1394 Standard For A High Performance Serial Bus,” Draft ratified in 1995, is an international standard for implementing an inexpensive high-speed serial bus architecture which supports both asynchronous and isochronous format data transfers. Isochronous data transfers are real-time transfers which take place such that the time intervals between significant instances have the same duration at both the transmitting and receiving applications. Each packet of data transferred isochronously is transferred in its own time period. The IEEE 1394-1995 standard bus architecture provides multiple channels for isochronous data transfer between applications. A six bit channel number is broadcast with the data to ensure reception by the appropriate application. This allows multiple applications to simultaneously transmit isochronous data across the bus structure. Asynchronous transfers are traditional data transfer operations which take place as soon as possible and transfer an amount of data from a source to a destination.
The IEEE 1394-1995 standard provides a high-speed serial bus for interconnecting digital devices thereby providing a universal I/O connection. The IEEE 1394-1995 standard defines a digital interface for the applications thereby eliminating the need for an application to convert digital data to analog data before it is transmitted across the bus. Correspondingly, a receiving application will receive digital data from the bus, not analog data, and will therefore not be required to convert analog data to digital data. The cable required by the IEEE 1394-1995 standard is very thin in size compared to other bulkier cables used to connect such devices. Devices can be added and removed from an IEEE 1394-1995 bus while the bus is active. If a device is so added or removed the bus will then automatically reconfigure itself for transmitting data between the then existing nodes. A node is considered a logical entity with a unique address on the bus structure. Each node provides an identification ROM, a standardized set of control registers and its own address space.
The IEEE 1394-1995 standard defines a protocol as illustrated in FIG.
1
. This protocol includes a serial bus management block
10
coupled to a transaction layer
12
, a link layer
14
and a physical layer
16
. The physical layer
16
provides the electrical and mechanical connection between a device or application and the IEEE 1394-1995 cable. The physical layer
16
also provides arbitration to ensure that all devices coupled to the IEEE 1394-1995 bus have access to the bus as well as actual data transmission and reception. The link layer
14
provides data packet delivery service for both asynchronous and isochronous data packet transport. This supports both asynchronous data transport, using an acknowledgement protocol, and isochronous data transport, providing real-time guaranteed bandwidth protocol for just-in-time data delivery. The transaction layer
12
supports the commands necessary to complete asynchronous data transfers, including read, write and lock. The serial bus management block
10
contains an isochronous resource manager for managing isochronous data transfers. The serial bus management block
10
also provides overall configuration control of the serial bus in the form of optimizing arbitration timing, guarantee of adequate electrical power for all devices on the bus, assignment of the cycle master, assignment of isochronous channel and bandwidth resources and basic notification of errors.
An exemplary IEEE 1394-1995 consumer entertainment system network including a settop box, a satellite dish, a television and a digital video cassette recorder (VCR) is illustrated in FIG.
2
. The settop box
20
is coupled to receive broadcast transmissions from the satellite dish
18
by the IEEE 1394-1995 cable
26
. Typically, these broadcasts are transmitted from the satellite dish
18
to the settop box
20
in an MPEG format. The settop box
20
is coupled to the television
22
by the IEEE 1394-1995 cable
28
. The television
22
is coupled to the digital VCR
24
by the IEEE 1394-1995 cable
30
. Through the single plug coupled to the IEEE 1394-1995 cable
28
, the tuner
20
transmits broadcasts from the satellite dish
18
to the television
22
and the digital VCR
24
.
The AV/C Digital Interface Command Set is a command set used for transactions between consumer audio/video equipment over an IEEE 1394-1995 serial bus. Neither the IEEE 1394-1995 serial bus nor the AV/C Command Set provide a master-slave relationship between the devices coupled within the IEEE 1394-1995 serial bus network. Instead, both the IEEE 1394-1995 serial bus and the AV/C Command Set operate based on the cooperative coexistence of devices within the network.
As discussed above, an IEEE 1394-1995 device includes the capability to transmit and receive isochronous data over multiple channels. However, in current implementations, certain IEEE 1394-1995 devices are being built with the capability to only transmit isochronous data over a single channel through a single source plug and receive isochronous data over a single channel through a single destination plug. This implementation allows manufacturers to make less expensive devices, but can cause problems and conflicts between devices sharing the data that is transmitted through the single source plug. Certain problems are envisioned in the manner that data streams will be controlled over the IEEE 1394-1995 serial bus particularly in the areas of multiple simultaneous selections and bandwidth management and device overflow. Multiple simultaneous selections present a problem when several controllers are utilizing a single source, such as a tuner subunit. There is presently no fixed relationship between the amount of information that can be selected by a sourcing device, such as the tuner
20
, and the means by which that information is made available to other subunits outside of the sourcing device, over the IEEE 1394-1995 serial bus, through the sourcing device's source plugs. Current implementations however, allow a sourcing device to support only a single source plug.
As illustrated within the exemplary network of
FIG. 2
, the tuner or settop box
20
is coupled to the satellite dish
18
by the IEEE 1394-1995 cable
26
to receive broadcast transmissions from the satellite dish
18
. The tuner
20
through a single source plug provides the broadcast transmissions to the television
22
and the digital VCR
24
over the IEEE 1394-1995 serial bus. It is possible for the tuner subunit
20
to receive, decode and distribute several select broadcasts received from the satellite dish
18
, thereby supporting many individual selection requests. This support is limited only by the bandwidth of the IEEE 1394-1995 serial bus and the capabilities of the tuner
20
. For example, the tuner
20
can simultaneously receive, decode and distribute the CNN® and BBC® broadcast services. Because there is only one plug through which the tuner
20
is transmitting, the data representing these broadcasts is multiplexed from the tuner
20
through the single source plug, with alternating packets of both broadcasts on the single IEEE 1394-1995 isochronous channel and distributed to the television
22
and the digital VCR
24
, as appropriate.
Problems arise when the data on the shared isochronous channel conflicts or exceeds the bandwidth of one of the devices. Illustrative of the problems that can arise in such a situation is the example of two controllers selecting the same service at the same time. In such a situation, both the television
22
and the digital VCR
24
request that the tuner
20
transmit the same service, such as the CNN® broadcas
Cardone Jason D.
Haverstock & Owens LLP
Sony Corporation
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