Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
1997-10-02
2001-04-10
Marcelo, Melvin (Department: 2663)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
Reexamination Certificate
active
06215798
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention pertains in general to synchronization of data frames transmitted across multiple parallel channels, and more particularly, to the use of pseudo noise sequences to align data frames transmitted across multiple parallel channels.
2. Description of Related Art
To achieve higher data transmission rates in mobile telephone systems, data frames from a wide bandwidth communication channel are sequentially divided up for transmission across multiple narrow bandwidth communication channels as described in Patent Cooperation Treaty documents WO 96/18248 and WO 95/31878. Multiple communication channels are required due to the narrower bandwidth. Data frames transmitted over the communication channels are reconstructed at a destination to form the original data stream. Various physical channels of the mobile telephone system are independent from one another, and propagation delay times through the mobile telephone system vary from one physical channel to another. As data frames are received at the destination, they are reconstructed in the appropriate order to form the original data stream.
To be able to reconstruct the data frames in the appropriate order in the receiver, inband information is inserted into each data frame. The inband information typically consists of three bits identifying a parallel channel number which the data frame has been assigned to, and synchronization information identifying the position of the data frame relative to data frames assigned to other parallel channels. Synchronization information is required because the propagation delay through the mobile telephone system varies between different physical channels. The synchronization information is used to insure that data frames from one parallel channel are aligned with appropriate data frames from another parallel channel.
As the data frames are received at the destination, they are reassembled into the appropriate parallel channel as determined by the inband parallel channel identification information. Although the parallel channel affiliation of each data frame is immediately known once it is received at the destination, the alignment of data frames from one parallel channel to another needs to be determined from a series of data frames from the same parallel channel. One solution uses a single bit to synchronize the data frames. For longer delay variances, however, a single bit is insufficient. Another solution uses a series of bits comprising a logical one followed by logical zeros. Synchronization between the data frames is established only after a sufficient number of data frames are received. Once the data frames from the parallel channels are aligned, the original data stream is reconstructed.
A first drawback associated with the current method of synchronization is that a large number of data frames from one parallel channel must be received before synchronization is achieved.
A second drawback involves bit errors which occur frequently on the air interface of mobile telephone systems. The current method of synchronization is not robust against bit errors and synchronization can be lost.
A third drawback is the requirement that parallel channel identification information must be inserted into each of the data frames. This information is “overhead” which reduces the overall bandwidth of the transmission.
It would be advantageous, therefore, to devise a method and apparatus for synchronizing data frames without requiring receipt of a large number of data frames. It would also be advantageous if such a method and apparatus provided better protection against bit errors. Furthermore, it would be advantageous if such a method and apparatus eliminated the need for inserting parallel channel number information into the data frames.
SUMMARY OF THE INVENTION
The present invention comprises a method and apparatus for synchronizing data frames from a wide bandwidth data stream which is divided up and transmitted across a plurality of parallel channels in a mobile telephone system. Alignment between equally positioned data frames within different parallel channels is achieved by inserting a common bit from a repeating pseudo noise synchronization sequence into equally positioned data frames before transmission. Upon receiving the data frames at a destination receiver, the synchronization bit is extracted from each data frame. A series of sequential synchronization bits from each parallel channel is compared against the original pseudo noise synchronization sequence to identify the position of each data frame relative to the other data frames in order to reconstruct the original wide bandwidth data stream.
REFERENCES:
patent: 4004100 (1977-01-01), Takimoto
patent: 4791653 (1988-12-01), McFarland et al.
patent: 4939734 (1990-07-01), Johannes
patent: 5237586 (1993-08-01), Bottomley
patent: 5258980 (1993-11-01), Maebara et al.
patent: 5291515 (1994-03-01), Yoshitaka
patent: 5392289 (1995-02-01), Varian
patent: 5581547 (1996-12-01), Umeda et al.
patent: 5727018 (1998-03-01), Wolf et al.
patent: 5862132 (1999-01-01), Blanchard et al.
patent: 5923667 (1999-07-01), Poiraud et al.
patent: 5926471 (1999-07-01), Shoji
patent: 0 659 001 (1995-06-01), None
patent: 9531878 (1995-11-01), None
patent: 9618248 (1996-06-01), None
patent: WO 96/18248 (1996-06-01), None
Shu Lin, et al., “Self-Sychronizing Outer Codes for the TDRSS Decoder1”, Nov. 28-Dec. 1, 1983, pp. 1050-1053.
Anderson Per-Olof
Bakhuizen Martin
Carneheim Caisa
Malm Lars
Jenkens & Gilchrist
Marcelo Melvin
Nguyen Phuongchau Ba
Telefonaktiebolaget LM Ericsson (publ)
LandOfFree
Multi-frame synchronization for parallel channel transmissions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multi-frame synchronization for parallel channel transmissions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multi-frame synchronization for parallel channel transmissions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2459627