Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1999-04-01
2002-10-15
Ton, Dang (Department: 2735)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
Reexamination Certificate
active
06466585
ABSTRACT:
The present invention relates generally to the communication of multimedia information, such as multimedia information formatted pursuant to the RealTime Transport Protocol (RTP). More particularly, the present invention relates to apparatus, and an associated method, for converting realtime multimedia information, formatted in packet data form, such as that formatted pursuant to the RTP, into a form to facilitate transmission of the information on a radio channel. Operation of an embodiment of the present invention permits the communication of multimedia information by way of a cellular, or other radio communication system, with minimal and constant time delay while also communicating the information in a spectrally-efficient manner.
BACKGROUND OF THE INVENTION
Advancements in communication technologies have permitted the introduction of, and popularization of, new types of, and improvements in existing, communication systems. Increasingly large amounts of data are permitted to be communicated at increasing thruput rates through the use of such new, or improved, communication systems. As a result of such improvements, new types of communications, requiring high data thruput rates, are possible. Digital communication techniques, for instance, are increasingly utilized in communication systems to efficiently communicate digital data, and the use of such techniques has facilitated the increased data thruput rates.
Multimedia communications, for instance, are exemplary of new types of communications permitted as a result of the improvements in communications technologies. Multimedia communications refer, generally, to the communication of more than one type of data between a sending station and a receiving station. Typically, the communication of such more than one type of data appears, to a user, to be simultaneous. Multimedia communications include, for instance, voice-over-data applications. Audio signals overlaid upon video signals used to effectuate teleconferencing is an example of a multimedia communication application. Two-way white board communication is exemplary of another multimedia communication application.
The different types of data exhibit different communication requirements. For instance, voice data must be communicated in real-time. That is to say, voice data must be communicated without significant delay and must be communicated in a manner which permits its reconstruction at a receiving station in a manner which introduces minimal time distortion. Otherwise, the voice data shall appear to be noticeably distorted. Conversely, non-voice data is not as time-sensitive. However, more stringent accuracy requirements are associated with non-voice data.
Multimedia communications can be effectuated utilizing packet data communication techniques. With the popularization of the Internet and communication thereon, standardized, multimedia protocols have been set forth by which to communicate multimedia information in a form amenable to its transmission by way of the Internet. An example of multimedia protocol is H.323. H.323 is a widely used ITU standard which uses RTP.
According to the H.323 protocol, when multimedia data is to be transmitted by a sending station, logical channels upon which to transmit the data are assigned. The data channels are allocated responsive to requests made by the sending station. Separate logical channels are requested for separate types of data. For instance, a first logical channel is requested upon which to transmit voice data, and allocation of a second logical channel is requested for transmission of non-voice data. A subset of the H.323 protocol, referred to as the H.245 protocol, defines the manner in which the channels are requested. Packets of data are thereafter transmitted upon the logical channels. In conventional manner, the individual packets include header information, such as IP, UDP and RTP information, to identify to where the packet is to be directed and to provide a time stamp with the packet. The information of a packet of data, referred to as the payload, is appended to the header information.
The H.323 protocol was intended originally for wireline communications, such as between communication stations, connected by wireline connections including those of the Internet. But, advancements in communication technologies have also permitted the widespread usage of radio communication systems. A cellular communication system is exemplary of a wireless communication system which has achieved wide levels of popularity and usage. Telephonic communication by way of a cellular communication system mimics communication by way of a conventional wireline, telephonic system. However, because a radio-link is utilized in a cellular, or other radio, communication system, bandwidth considerations are generally more significant than when wireline networks are utilized for communications. That is to say, the radio-link upon which communication is communicated in a radio communication system is of a limited bandwidth capacity. And, by reducing the bandwidth requirements of information communicated thereon, the information capacity of the radio-link can be increased. So, efforts are made to minimize the bandwidth requirements of signals transmitted over the radio-link.
Information communicated pursuant to an H.323 protocol is predicated upon a packet-data configuration. The header information required of each packet of data is relatively bandwidth-consumptive. As a result, communication of multimedia information by way of a radio-link, such as that formed in the operation of a cellular communication system, is a relatively inefficient manner by which to communicate multimedia information. However, because the RTP-based protocol has become a de facto standard by which to format multimedia information, multimedia stations shall likely continue to be operable pursuant to such protocol irrespective of the bandwidth inefficiency of communication of packet data by way of the radiolink.
If a manner could be provided by which more efficiently to communicate multimedia information by way of a radio-link, while still utilizing the RTP-based protocol at the sending and receiving stations, improved multimedia communications by way of a radio communication system could result.
It is in light of this background information related to multimedia communications that the significant improvements of the present invention have evolved.
SUMMARY OF THE INVENTION
The present invention, accordingly, advantageously provides apparatus, and an associated method, for converting real-time multimedia information formatted in packet-data form, into a form to facilitate transmission of the information on a radio channel. Through such conversion, the multimedia information can be transmitted with minimal time delay while also being transmitted upon the radio channel in a spectrally efficient manner.
In one aspect of the present invention, real-time media, which is part of multimedia information, is communicated between sending and receiving multimedia stations. On the communications path between the sending and receiving stations there is a communications link, such as a radio link, that has bandwidth limitations and spectrum efficiency requirements. In what follows, that link shall, at times, be referred to as the communications link. The multimedia information, when generated at a sending multimedia station, and when provided to a receiving multimedia station, is formatted in packet-data form according to an existing RTP protocol. Before transmission on the communications link, real-time media is converted into a communications-link format. Once converted into the communications-link format, the real-time media can be transmitted upon a special channel on the communications-link in an efficient manner. Once received, the real-time media is converted out of the communications-link format and back into the packet-data format before being sent to the receiving station. The same process takes place in the reverse direction. A special channel is defined as a channel that pro
Fraccaroli Federico
Nokia Corporation
Ton Dang
LandOfFree
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