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Description  |
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FIELD OF THE INVENTION
The present invention relates to the field of networked computer systems.
Specifically, the present invention relates to a method and apparatus for
transmitting high bandwidth network content on a low bandwidth
communications channel during off peak hours.
DESCRIPTION OF RELATED ART
With the advent of consumer-oriented services on global networks such as
the Internet, there has been an explosion of interest in delivering these
services to users in their homes. Private on-line services such as America
On-line (AOL.TM.), Internet Service Providers (ISPs) such as Netcom.TM.,
and television-based Internet services such as the WebTV.TM. Network from
WebTV Networks, Inc., are all seeking to provide on-line services to
typical consumers in their homes.
Unfortunately, the world's residential communication infrastructure was not
designed to accommodate the high-bandwidth, two-way requirements of
on-line services. Consequently, usage in the home is, for the most part,
limited to "plain old telephone service" or "POTS" modems and Integrated
Services Digital Network (ISDN) services. Although modems are becoming
increasingly more efficient in utilizing the bandwidth of a telephone
voice channel, they are ultimately limited to the 64 Kbps digitization of
voice channels in the switched telephone network. ISDN, in some countries,
can provide approximately 128 Kbps in bandwidth. That is, however, the
upper limit in bandwidth for two-way communications using today's
available infrastructure to homes.
Although there are other experimental and proposed technologies to provide
two-way high-bandwidth communications to the home beyond 128 Kbps, none of
these technologies have been deployed to any significant degree on a
nationwide or worldwide basis. For example, Asynchronous Digital
Subscriber Loop (ADSL) uses the telephone twisted pair going to the home
from the telephone central office to provide over 1 Mbps of downstream (to
the home) bandwidth and lower upstream bandwidth. Cable modems, utilizing
the Cable TV (CATV) infrastructure can provide over 10 Mbits of downstream
bandwidth and over 1 Mbps of upstream bandwidth. Also, hybrid approaches
have been proposed in which a POTS telephone modem provides a
low-bandwidth upstream channel while a one-way cable modem, a Direct
Broadcast Satellite (DBS) feed, or even a terrestrial broadcast provides
the downstream channel at over 10 Mbits/sec,
Each of these high-bandwidth technologies has significant infrastructure
upgrade implications and/or significant scalability limitations. For
example, ADSL requires the installation of ADSL modems in every telephone
central office. Clearly, this amounts to a monumental undertaking. Cable,
DBS, and terrestrial communications systems are broadcast architectures
with limited overall bandwidth which is easily swamped when it is used for
individual messages to potentially thousands, or even millions, of
subscribers. Although a given cable plant can theoretically be segmented
into independent subtrees to handle more individual messages, there are
still monumental infrastructure upgrade implications.
Thus, given the bandwidth limitations of current communications
infrastructure to the home, and given the high cost, monumental upgrade
implications, and limitations of proposed new infrastructure, better
methods are needed to bring high-bandwidth content services into the home
using existing infrastructure.
SUMMARY OF THE INVENTION
The present invention describes a method for transmitting high bandwidth
network content on a low bandwidth communications channel during off peak
hours. According to one embodiment of the present invention, criteria is
determined for downloading data from the communications channel and the
data is downloaded from the communications channel during off-peak hours
based on the determined criteria.
According to another embodiment, a method for coordinated multicasts on a
network is described. Download requests are received on a server from a
plurality of clients on the network and stored on the server for the
coordinated multicast. The coordinated multicast is generated at a
predetermined time and then broadcast from the server to the plurality of
clients at the predetermined time.
Other objects, features and advantages of the present invention will be
apparent from the accompanying drawings and from the detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is illustrated by way of example and not by way of
limitation in the figures of the accompanying drawings in which like
reference numerals refer to similar elements and in which:
FIG. 1A is a typical computer system in which the present invention
operates.
FIG. 1B is an alternate computer system (a WebTV system) in which the
present invention operates.
FIGS. 2A and 2B illustrate the currently available devices and services on
the Internet today
FIGS. 3A-3D illustrate multicast or broadcast data streams according to
various embodiments of the present invention
FIG. 4 illustrates prior art utilization of idle time and off-peak time on
a network
FIG. 5 illustrates improved utilization of idle time and off-peak time on a
network according to one embodiment of the present invention
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention is a method and apparatus for transmitting high
bandwidth network content on a two-way low bandwidth communications
channel during off peak hours. One embodiment of the present invention
utilizes typical on-line services and Internet usage patterns as well
usage patterns of existing communications channels to provide the user of
a low bandwidth communications channel with an experience similar to the
experience enjoyed by users utilizing a high-bandwidth communication
channel. In the following detailed description, numerous specific details
are set forth in order to provide a thorough understanding of the present
invention. It will be apparent to one of ordinary skill in the art that
these specific details need not be used to practice the present invention.
In other instances, well-known structures, interfaces, and processes have
not been shown in detail in order not to unnecessarily obscure the present
invention.
FIG. 1A illustrates a typical computer system 100 in which the present
invention operates. One embodiment of the present invention is implemented
on a personal computer architecture. It will be apparent to those of
ordinary skill in the art that other alternative computer system
architectures may also be employed.
In general, such computer systems as illustrated by FIG. 1A comprise a bus
101 for communicating information, a processor 102 coupled with the bus
101 for processing information, main memory 103 coupled with the bus 101
for storing information and instructions for the processor 102, a
read-only memory 104 coupled with the bus 101 for storing static
information and instructions for the processor 102, a display device 105
coupled with the bus 101 for displaying information for a computer user,
an input device 106 coupled with the bus 101 for communicating information
and command selections to the processor 102, and a mass storage device
107, such as a magnetic disk and associated disk drive, coupled with the
bus 101 for storing information and instructions. A data storage medium
108 containing digital information is configured to operate with mass
storage device 107 to allow processor 102 access to the digital
information on data storage medium 108 via bus 101.
Processor 102 may be any of a wide variety of general purpose processors or
microprocessors such as the Pentium.RTM. microprocessor manufactured by
Intel.RTM. Corporation. It will be apparent to those of ordinary skill in
the art, however, that other varieties of processors may also be used in a
particular computer system. Display device 105 may be a liquid crystal
device, cathode ray tube (CRT), or other suitable display device. Mass
storage device 107 may be a conventional hard disk drive, floppy disk
drive, CD-ROM drive, or other magnetic or optical data storage device for
reading and writing information stored on a hard disk, a floppy disk, a
CD-ROM a magnetic tape, or other magnetic or optical data storage medium.
Data storage medium 108 may be a hard disk, a floppy disk, a CD-ROM, a
magnetic tape, or other magnetic or optical data storage medium.
In general, processor 102 retrieves processing instructions and data from a
data storage medium 108 using mass storage device 107 and downloads this
information into random access memory 103 for execution. Processor 102,
then executes an instruction stream from random access memory 103 or
read-only memory 104. Command selections and information input at input
device 106 are used to direct the flow of instructions executed by
processor 102. Equivalent input device 106 may also be a pointing device
such as a conventional mouse or trackball device. The results of this
processing execution are then displayed on display device 105.
Computer system 100 includes a network device 110 for connecting computer
system 100 to a network. Network device 110 for connecting computer system
100 to the network includes Ethernet devices, phone jacks and satellite
links. It will be apparent to one of ordinary skill in the art that other
network devices may also be utilized.
Another embodiment of the present invention is implemented on a system
known as WebTV, by WebTV Networks, Inc., Palo Alto. The WebTV system uses
a standard television set as a display device for browsing the Web and
connects to a conventional network, such as the Internet, using standard
telephone, Integrated Services Digital Network (ISDN), or similar
communication lines. A user of a WebTV client system can utilize WebTV
network services provided by one or more remote WebTV servers. The WebTV
network services can be used in conjunction with software running in a
WebTV client system to browse the Web, send electronic mail, and to make
use of the Internet in various other ways. The WebTV network uses a
HyperText Transport Protocol (HTTP) based set of protocols implemented
within the Web and supported by one or more Web servers.
FIG. 1B illustrates a basic configuration of the WebTV network according to
one embodiment. A number of WebTV clients 180 are coupled to a modem pool
170 via direct-dial, bi-directional data connections 175, which may be
telephone (POTS, i.e., "plain old telephone service"), ISDN (Integrated
Services Digital Network), or any other similar type of connection. Modem
pool 170 is coupled typically through a router, such as that
conventionally known in the art, to a number of remote servers 150 via a
conventional network infrastructure 165, such as the Internet.
The WebTV system also includes a WebTV server 160, which specifically
supports the WebTV clients 180. WebTV server 160 acts as a proxy in
providing the WebTV client 180 with access to the Web and other WebTV
services. More specifically, WebTV server 160 functions as a "caching
proxy." A proxy cache on WebTV server 160 is used for temporary storage of
Web documents, images, and other information which is used by frequently
either the WebTV client 180 or the WebTV server 160.
WebTV clients 180 each have a connection to the WebTV server 160 either
directly, via a WebTV modem pool 175, similar to modem pool 170, or
through the conventional modem pool 170 and the Internet 165. Note that
the modem pool 170 is a conventional modem pool, such as those found today
throughout the world providing access to the Internet and private
networks. Further details of the WebTV system, including the WebTV client
can be found in co-pending U.S. Patent application entitled, "Web Browser
Allowing Navigation Between Hypertext Objects Using Remote Control,"
having application no. 08/660,088, and filed on Jun. 3, 1996.
One embodiment of the present invention is implemented as a software
module, which may be executed on a computer system such as computer system
100 or WebTV server 160 in a conventional manner. Using well known
techniques, the application software of the preferred embodiment is stored
on data storage medium 108 and subsequently loaded into and executed
within computer system 100 or WebTV server 160. Once initiated, the
software of this embodiment operates in the manner described below.
FIG. 2A illustrates the variety of communications channels currently
available to the typical home on-line service subscriber in an
industrialized country such as the United States, Japan, or the United
Kingdom. The arrows indicate the direction(s) of data flow over a given
channel.
A user browsing the Internet today can select specific content such as web
pages, video clips, audio clips or advertisements. This selected content
is typically stored on servers on the Internet, identified in FIG. 2A as
content server 210. Since these content servers are usually maintained at
commercial locations, very high bandwidth communications channels such a
T1 or T3 lines are available to connect them to either a TCP/IP network,
such as the Internet or a Virtual Private Network (VPN), or other
packet-switched networks, such as X.25. Content servers may also be
connected to conventional broadcast channels 200 including a CATV channel,
a terrestrial channel, or a DBS channel. Because of the nature of these
conventional broadcast channels 200, however, they are typically limited
to transmitting data in a single downstream direction, namely from the
content server to the client.
Such content servers can be located at one site or at many sites throughout
the world. In fact, it is quite possible to replicate such content servers
in several locations so as to minimize the communications channel
resources used by bringing a content server closer to each subscriber and
to provide redundancy in the event of a server or communications failure.
FIG. 2B illustrates a common configuration today for personal computer (PC)
and network-enabled set-top boxes and video game consoles. Client network
interface device (client device) 302 may include a device such as a
WebTV.TM. set-top box, a video game system or a PC, that incorporates
features described in computer system 100 above. Connected to client
device 202 is a network interface device 224, such as a POTS modem, an
ISDN adapter, a cable modem or an ADSL modem. Also connected to client
device 202 is caching store 220. Caching store 220 may include a hard
disk, a digital video disk (DVD), flash Read-Only Memory (ROM), or Random
Access Memory (RAM). Other client devices, network interface devices and
caching stores may also be utilized.
Network interface device 224 connects to a two-way wide-area network (WAN)
226. According to one embodiment of the present invention, two-way WAN 226
is a switched telephone network (POTS or ISDN). ADSL, two-way cable plant,
or other two-way network technology may also be utilized. Given the
current infrastructure that is widely available for homes throughout the
world, a POP is necessary to connect the home to the packet-switched WAN.
Thus, as illustrated in FIG. 2B, POP 206 connects the two-way WAN to a
packet-switched WAN 230 such as a TCP/IP network (e.g. the Internet or a
VPN) or an X.25 network. In the event that a packet-switched WAN 230 can
be delivered directly to the home in the future, POP 206 will no longer be
necessary. Finally, within reach of the packet-switched wide area network
is at least one content server 210 containing content potentially of
interest to the user of client device 202.
Typically, the user of client device 202 decides that he or she is
interested in certain content available on one or more content servers
210. The user connects his or her client device 202 to a WAN such as the
Internet or a private on-line service such as AOL.TM.. This is generally
accomplished by client software executing on client device 202 dialing the
phone number of POP 206, going through an authentication procedure to
establish the validity of the user's on-line account, and then providing
the user with an on-line navigation means. The on-line navigation means
may be through a general-purpose Hyper-Text Markup Language (HTML)
browser, such Netscape Navigator.TM. or Microsoft.TM. Internet Explorer,
or through a proprietary on-line browser such as the AOL client software.
If the user is seeking a particular content item, there are various tools
such a search engines and catalogs that the user can use to search for the
content. Once that item is found, the user typically clicks the mouse on a
hyperlink to that item. The hyperlink in turn directs the client software
to initiate a download into their client device 202. Depending on the data
size of the content selected, the communications bandwidth, the network
traffic, and the load on content server 210 holding the content, the
download time may vary. The download may complete almost instantly or take
minutes or hours. Upon completion of the download, the user may experience
a visual result such as a picture or a video clip, or an auditory result
such as music. Alternatively, the download may simply be a file that is
stored in memory or on a disk for later use.
Although a download theoretically may complete very quickly, the typical
experience of the home Internet or on-line service user is that downloads
are very slow, even for relatively small data items. There are a number of
factors that can make the download very slow, but even if all of the
stages of the download are working at optimum efficiency, the home user is
typically still limited to the bandwidth limitations of the switched
telephone network.
ISPs such as AT&T WorldNet.TM. and WebTV Networks, Inc. offer flat-rate
Internet access. While such flat rates are offered on the expectation of a
certain average utilization of POP and network resources by the overall
subscriber base, the ISP's primary concern is utilization during peak
usage hours (Monday-Friday, 9 am-5 pm for business usage, evenings and
weekend daytime for home usage). This is due to the fact that an ISP has a
certain number of modems available in its POPs and a certain amount of
bandwidth between its POPs and its servers to the Internet. The ISP must
ensure that it has a sufficient number of modems and adequate bandwidth
for peak usage. Otherwise, users will get busy signals or poor performance
when they dial in for service during peak times. Thus, for an ISP to
provide good service to its customer base, it must provide enough POP
modems and enough bandwidth for peak usage.
Notably, an ISP's modem and bandwidth resources (collectively "ISP
infrastructure") are largely idle during off-peak hours. Which hours of
the day qualify as "off-peak hours" vary depending on a given ISP's
customer base. In both the case of business and home customer base,
however, traffic is typically light during late night and early mornings,
7 days a week in each time zone. During these hours, an ISP is amortizing
equipment and paying for communications bandwidth on leased lines without
utilizing the equipment. Thus, theoretically, if a large percentage of an
ISP's user base were to connect to the ISP during these hours, it would
have little or no impact on the ISP's costs of providing Internet access,
so long as the number of users was less than its peak number of users,
even though it would drastically increase the average number of on-line
hours per month per user.
Following this supposition further, the telephone costs to the user for
connecting during these off-peak hours would be zero or quite low,
assuming the dialed POP was in a given user's local calling area. As
described above, in the United States, residential local calls are
generally charged at a flat-rate per month, regardless of duration. In
other countries, local calls during off-peak hours are often cheaper than
during peak hours. For example, in Japan, while local calls during peak
hours are charged by the minute, a flat-rate service plan is available
between the hours of 11 PM and 7 AM. Like the ISPs, phone companies must
provide equipment and bandwidth to accommodate peak loads. During off-peak
hours, this equipment and bandwidth sits idle, so the company may desire
to incent users to utilize the equipment during these hours.
According to one embodiment of the present invention, the methods of
on-line communications using the configuration shown in FIG. 1B are
improved significantly. The improvements take advantage of the fact that,
as described above, typically in the home, a client device is utilized
only during certain hours of the day. The presently claimed invention
leverages the usage patterns to provide many of the characteristics of
high-bandwidth two-way communications by heavily utilizing infrastructure
during off-peak times.
In one embodiment of the present invention, the client software allows the
user to specify content that the user desires to access. For example, if
the user is interested in news, the user might identify CNN.TM.
Interactive, a web site that contains news items, as a web site of
interest. During off-peak hours (when the user is probably asleep) the
client software on client device 202 will direct client device 202 and
network interface device 124 to automatically dial into to a local POP
132, provide appropriate authentication, and then download all of the
content the user has specified to be of interest. In the case of the CNN
Interactive web site, the client software may explore all of the links
originating from the root home page (i.e. http://www.cnn.com/) to some
level of depth (e.g. to all pages within the cnn.com domain). As each web
page comes in, its content will be stored in caching store 220.
Some of the links may very well contain large quantities of data, such as
compressed video, which using currently known techniques, is only
convenient to download through a high bandwidth connection. Alternatively,
according to this embodiment of the present invention, the client software
will have several off-peak hours to complete the downloads and will thus
be able to download these large data items over a standard lowbandwidth
communications mechanism. For example, at 33.6 Kbps, 118 MBytes of data
can be downloaded in 8 hours. 1 minute of MPEG 1 video is about 10 MBytes
of data. Currently, a user with a 33.6 Kbps modem would wait almost an
hour to download 1 minute of video. According to this embodiment, however,
the user may specify this type of content to be downloaded overnight. The
next day, the video may be viewed in real-time from caching store 220.
The mechanism described above has significant advantages over currently
available techniques. According to other embodiments of the present
invention described below, further refinements provide for a better
experience to the user and better resource utilization for the ISP.
A. Blind Downloads
One potential problem with the off-peak download mechanism just described
is that if the client software blindly downloads conten | | |
