Multiplex communications – Channel assignment techniques – Combining or distributing information via time channels...
Reexamination Certificate
1998-08-27
2001-10-23
Olms, Douglas (Department: 2661)
Multiplex communications
Channel assignment techniques
Combining or distributing information via time channels...
C370S345000, C370S347000
Reexamination Certificate
active
06307863
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a transmission method for communication signals, and to a communication system employing the method. The invention is particularly concerned with systems employing time division multiple access (TDMA) channel sharing.
BACKGROUND OF THE INVENTION
In known TDMA systems, a predetermined series of time segments of a transmission channel is allocated to the transmission of a particular data signal. The allocation of time segments of the channel is independent of the timing of the data input. It is also known to provide a queue of signals awaiting transmission and to provide that more urgent data may jump to the front of the queue for transmission using the next available allocated time segment.
For certain types of data communication there is a need to reduce as far as possible the transmission delay, for example for a two way speech or video transmission. A problem with existing TDMA systems is that delays may arise between the preparation of data packets for transmission and the availability of allocated time segments for that data.
SUMMARY OF THE INVENTION
According to the invention there is provided a method of transmitting a plurality of communication signals over a channel using time division multiple access sharing of the channel, each communication signal comprising a data sequence which is divided into data packets for transmission over the channel during respective subsequent time segments of the channel, characterised in that the division of each communication signal into data packets is synchronised with the allocation of time segments of the channel to the respective signal.
The synchronisation of the allocation of time segments with the creation of data packets can be made to eliminate any delays which are conventionally introduced while a prepared data packet is awaiting the next allocated time segment for transmission. The creation of data packets may be timed so that the allocated time segment is available shortly after creation of the data packet. In this case the predetermined allocation of time segments may be maintained. However, the allocation of time segments may alternatively be varied so that a time segment is allocated to a communication signal shortly after the creation of a data packet from the respective signal.
Interleaving may be employed in the transmission method, such that each data packet is transmitted using a block of successive time segments of the channel, so that the division of each communication signal into data packets further comprises the spreading of data from each packet into data portions for respective time frames of the block, and the timing of the start of a block of time segments is then synchronised with the creation of the data portions.
When the invention is applied to a transmission system employing interleaving, the sampling of the data signal may be timed so that the first time segment within a block of time segments is available shortly after generation of the interleaved data packets. Alternatively, the timing of the time segments may be varied such that the first time segment of a block of time segments is available shortly after creation of the interleaved data packets.
The invention also provides a radio transmission system for performing the transmission method of the invention.
REFERENCES:
patent: 6005855 (1999-12-01), Zehavil
patent: 6173005 (2001-01-01), Kotzin
patent: 6185200 (2001-02-01), Prasad
Halajian Dicran
Olms Douglas
Pizarro Ricardo M.
U.S. Philips Corporation
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