Multiplex communications – Pathfinding or routing – Store and forward
Reexamination Certificate
1998-11-05
2001-08-21
Ton, Dang (Department: 2661)
Multiplex communications
Pathfinding or routing
Store and forward
C370S412000
Reexamination Certificate
active
06278715
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to voice and data communications. In particular, the invention pertains to deinterleaving and decoding symbols received over a plurality of channels.
2. Description of the Related Art
A periodic stream of symbols is received by a deinterleaver and output to a decoder which processes the received symbols. If the deinterleaver deinterleaves the n symbols received during a frame period, then n symbols need to be received by the deinterleaver before being processed by the decoder. A typical bit-reversal deinterleaver would take the n symbols and write them into a two-dimensional table, row by row, and then read the n symbols out column by column, or vice versa. As a result, if the decoder needs to operate on the deinterleaved symbols in order, then typically, the deinterleaver must wait until almost all of the n symbols have been received. Thus, effectively, a periodic stream of symbols must be buffered in one place and then provided to the decoder when the n symbols have been received.
While the decoder is processing a buffer of n symbols, more symbols are being received by the deinterleaver. Therefore, the potential exists to overwrite symbols that have not yet been processed by the decoder. Known systems solve this problem by double-buffering the received symbols.
FIG. 1
shows a first buffer
10
and a second buffer
20
in a known system for deinterleaving and decoding symbols received during frame periods, n symbols being received during each frame period. Each buffer can store up to n symbols. When the symbols are first received from a deinterleaver
15
, n symbols are stored in, for example, first buffer
10
. After n symbols are received, the n symbols in first buffer
10
are then processed by a decoder
30
. However, while decoder
30
decodes the n symbols, a stream of symbols continues to be received by the deinterleaver. If the symbols are stored in first buffer
10
before the decoder completes processing, then the previously received symbols will be overwritten before being processed. In order to prevent this from occurring, known systems solve this problem by allocating a second buffer
20
to receive n symbols while the decoder processes the n symbols in buffer
10
. Since the process of decoding is faster than the process of receiving symbols from a deinterleaver, by the time n symbols are received and stored in buffer
20
, the decoder is again available and the symbols in buffer
20
can be processed by the decoder while buffer
10
is reallocated to receive another stream of n symbols.
SUMMARY OF THE INVENTION
The present invention provides a new arrangement for receiving and storing received symbols from a deinterleaver and decoding the received symbols. The system allocates memory for holding the received symbols, such that as symbols are received from a plurality of channels during frame periods, symbols received during previous frame periods for the plurality of channels are decoded, thereby freeing up memory holding the symbols, which have been decoded, to be re-allocated for the reception of new symbols. The system requires less buffer space than a conventional double-buffered system.
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patent: 6012159 (2000-01-01), Fischer et al.
patent: 6088387 (2000-07-01), Gelblum et al.
patent: 6094465 (2000-07-01), Stein et al.
patent: 0660558 (1995-06-01), None
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patent: 0715432 (1996-06-01), None
H. Huang and Chih-Lin I: “Combined Pilot Multipath Noise Cancellation and Partial Decorrelation for Coherent Multicode CDMA Receivers,” IEEE Global Telecommunications Conference, Nov. 3-8, 1997, pp. 904-909.
H.M. Kwon, S. Ratanamahatana, J.H. Shim: “One Viterbi Decoder with Data Rate Estimation for IS-95 CDMA Wireless Communications,” IEEE Global Telecommunications Conference, Nov. 3-8, 1997, pp. 594-598.
Hom Raymond B.
Qualcom Incorporated
Rouse Thomas R.
Sam Phirin
Ton Dang
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