EP0331115A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Scrambling/descrambling method using a memory for storing initial pseudo-random bit patterns respectively for submultiframes
Assignee: NEC Corp
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Filing: 1989-02-28
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Granted: —
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Expires: 2009-02-28
Abstract
Abstract In a communications system, a multiframe data signal is sent from a transmit end to a receive end of the system. The multiframe is composed of a series of submultiframes each containing a series of frames. Each frame in turn comprises a sync word for establishing the start timing of the frame, an identifier for uniquely identifying the submultiframe in which the frame is contained, and a specified number of data bits. A pseudo-random scrambling bit pattern, which repeats at intervals of multiframe and varies from one pattern to another at frame intervals, is generated as a scrambling bit pattern with which the data bits of each frame are scrambled prior to transmission. At the receive end, the sync word of each frame is detected to establish frame synchronization. A memory stores initial bit patterns each of which is identical to the pattern which was generated at the beginning of each submultiframe. The identifier is detected when frame sync is established and applied as a read address to the memory. The initial bit pattern of the submultiframe which is next to a one in which the establishment of frame sync occurred is read out of the memory into a pseudo-random sequence generator. The latter is activated at the beginning of the next submultiframe to generate a pseudo-random sequence, which successively varies at frame intervals and repeats the same pattern at multiframe intervals, for descrambling received data bits.
Inventors
- 👤 Tomoyuki Ooi
- 👤 Toshinori Hotta
- 👤 Yasuhito Isoe
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 04:36
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03828; H04L25/03866
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
269 words
A method for scrambling data bits at a transmit end of a communications system and descrambling the data bits at a receive end of the communications system, comprising: successively generating a multiframe composed of a series of submultiframes each containing a series of frames, each of said frames containing data bits, a sync word for establishing the start timing of the frame and an identifier for uniquely identifying the submultiframe in which the frame is contained; generating a scrambling bit pattern which successively varies in synchronism with said frames and repeats an identical bit pattern at intervals of said multiframe; scrambling said data bits of each frame with said scrambling bit pattern and transmitting said frames each containing the scrambled data bits and said sync word and identifier to said receive end of said system; receiving said transmitted frames at said receive end and establishing frame synchronization with the received frames in response to said sync word contained in each of the received frames; detecting said identifier from each of the received frames; storing a plurality of initial bit patterns in a memory, each of said initial bit patterns corresponding to a pattern which was generated at the beginning of each submultiframe at said transmit end; reading one of said initial bit patterns from said memory in accordance with said detected identifier; detecting the beginning of each of said submultiframes; generating a descrambling pattern which successively varies at intervals of said frames beginning with said initial bit pattern read out of said memory; and descrambling said data bits contained in each of said sync-established frames with said descrambling pattern.
Claim 2
Independent Claim
269 words
A method for scrambling data bits at a transmit end of a communications system and descrambling the data bits at a receive end of the communications system, comprising: successively generating a multiframe composed of a series of submultiframes each containing a series of frames, each of said frames containing data bits, a sync word for establishing the start timing of the frame and an identifier for uniquely identifying the submultiframe in which the frame is contained; generating a scrambling bit pattern which successively varies in synchronism with said frames and repeats an identical bit pattern at intervals of said multiframe; scrambling said data bits of each frame with said scrambling bit pattern and transmitting said frames each containing the scrambled data bits and said sync word and identifier to said receive end of said system; receiving said transmitted frames at said receive end and establishing frame synchronization with the received frames in response to said sync word contained in each of the received frames; detecting said identifier from each of the received frames; storing a plurality of initial bit patterns in a memory, each of said initial bit patterns corresponding to a pattern which was generated at the beginning of each submultiframe at said transmit end; reading one of said initial bit patterns from said memory in accordance with said detected identifier; detecting the beginning of each of said submultiframes; generating a descrambling pattern which successively varies at intervals of said frames beginning with said initial bit pattern read out of said memory; and descrambling said data bits contained in each of said sync-established frames with said descrambling pattern.
Claim 3
Dependent Claim
272 words
A communications system comprising: means for successively generating a multiframe composed of a series of submultiframes each containing a series of frames, each of said frames containing data bits, a sync word for establishing the start timing of the frame and an identifier for uniquely identifying the submultiframe in which the frame is contained; first pseudo-random sequence generator means for generating a successively varying scrambling bit pattern at intervals of said frames, said scrambling bit pattern cyclically repeating an identical bit pattern at intervals of said multiframes; means for scrambling said data bits of each frame with said scrambling bit pattern for transmission to a receive end of said system together with said sync word and identifier; means responsive to said sync word contained in each frame for establishing frame synchronization therewith; a memory for storing a plurality of initial bit patterns each corresponding to a bit pattern which was generated at the beginning of each submultiframe by said first pseudo-random sequence generator means; means for detecting said identifier from each frame and reading one of said initial bit patterns from said memory in accordance with said detected identifier; means for detecting the beginning of each of said submultiframes; second pseudo random sequence generator means arranged to be loaded with said initial bit pattern read out of said memory and responsive to the detection of the beginning of a submultiframe by said detecting means for generating a successively varying descrambling bit pattern at intervals of said frames beginning with said loaded initial bit pattern; and means for descrambling said data bits contained in each of the sync-established frames with said descrambling pattern.
Claim 4
Dependent Claim
272 words
A communications system comprising: means for successively generating a multiframe composed of a series of submultiframes each containing a series of frames, each of said frames containing data bits, a sync word for establishing the start timing of the frame and an identifier for uniquely identifying the submultiframe in which the frame is contained; first pseudo-random sequence generator means for generating a successively varying scrambling bit pattern at intervals of said frames, said scrambling bit pattern cyclically repeating an identical bit pattern at intervals of said multiframes; means for scrambling said data bits of each frame with said scrambling bit pattern for transmission to a receive end of said system together with said sync word and identifier; means responsive to said sync word contained in each frame for establishing frame synchronization therewith; a memory for storing a plurality of initial bit patterns each corresponding to a bit pattern which was generated at the beginning of each submultiframe by said first pseudo-random sequence generator means; means for detecting said identifier from each frame and reading one of said initial bit patterns from said memory in accordance with said detected identifier; means for detecting the beginning of each of said submultiframes; second pseudo random sequence generator means arranged to be loaded with said initial bit pattern read out of said memory and responsive to the detection of the beginning of a submultiframe by said detecting means for generating a successively varying descrambling bit pattern at intervals of said frames beginning with said loaded initial bit pattern; and means for descrambling said data bits contained in each of the sync-established frames with said descrambling pattern.
Claim 5
Dependent Claim
44 words
A communications system as claimed in claim 2, wherein the sync word of one of said frames which occurs at the beginning of each submultiframe has a bit pattern which is inverse to the bit pattern of the sync words of the other frames.
Claim 6
Dependent Claim
125 words
A communications system as claimed in claim 2 or 3, wherein said multiframe generating means comprises: unique word generator means for generating said sync word of a first pattern at intervals of said submultiframes and generating said sync word of a second pattern at intervals of said frames; identifier generator means for generating said identifier for each of said submultiframes at intervals of said submultiframes; and means for interleaving said sync word and said identifier with said data bits to form each of said frames, wherein said detecting means detects said sync word of said first pattern and said second pseudo-random sequence generator means is arranged to be reset in response to the detected sync word to begin generating said successively varying descrambling bit pattern.
Claim 7
Dependent Claim
226 words
A descrambler for receiving a multiframe composed of a series of submultiframes each containing a series of frames, each of said frames containing data bits, a sync word for establishing the start timing of the frame and an identifier for uniquely identifying the submultiframe in which the frame is contained, said data bits of each frame being scrambled with a successively varying scrambling bit pattern which cyclically repeats an identical bit pattern at intervals of said multiframes, said descrambler comprising: a memory for storing a plurality of initial bit patterns each corresponding to a descrambling bit pattern which is to be generated at the beginning of each submultiframe; means responsive to said sync word contained in each frame for establishing frame synchronization therewith; means for detecting said identifier from each frame and reading one of said initial bit patterns from said memory in accordance with said detected identifier; means for detecting the beginning of each of said submultiframes; pseudo-random sequence generator means arranged to be loaded with said initial bit pattern read out of said memory and responsive to the detection of a submultiframe by said detecting means for generating a successively varying descrambling bit pattern at intervals of said frames beginning with said loaded initial bit pattern; and means for descrambling said data bits contained in each of the sync-established frames with said descrambling pattern.
Claim 8
Dependent Claim
226 words
A descrambler for receiving a multiframe composed of a series of submultiframes each containing a series of frames, each of said frames containing data bits, a sync word for establishing the start timing of the frame and an identifier for uniquely identifying the submultiframe in which the frame is contained, said data bits of each frame being scrambled with a successively varying scrambling bit pattern which cyclically repeats an identical bit pattern at intervals of said multiframes, said descrambler comprising: a memory for storing a plurality of initial bit patterns each corresponding to a descrambling bit pattern which is to be generated at the beginning of each submultiframe; means responsive to said sync word contained in each frame for establishing frame synchronization therewith; means for detecting said identifier from each frame and reading one of said initial bit patterns from said memory in accordance with said detected identifier; means for detecting the beginning of each of said submultiframes; pseudo-random sequence generator means arranged to be loaded with said initial bit pattern read out of said memory and responsive to the detection of a submultiframe by said detecting means for generating a successively varying descrambling bit pattern at intervals of said frames beginning with said loaded initial bit pattern; and means for descrambling said data bits contained in each of the sync-established frames with said descrambling pattern.
References Cited (Backward Citations)
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