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Packet data broadcast systems require error free delivery of packet data without retransmission requests. Turbo codes can be used to achieve very low packet error rates. To achieve this low error rate with a very small gap from the system capacity, several design considerations need to be made. We need to use higher constraint- length codes (increa...
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In this paper, the design of error-correcting or channel codes for delay-universal/anytime communication is shown while considering systems with and without a feedback link. We construct practical and low complexity anytime channel codes based on spatially coupled repeat-accumulate (SC-RA) codes. Performance and density evolution analysis are shown...
Citations
... The spreading sequence has a length N , which is known as the processing gain or the spreading factor. For the HSDPA system the processing gain is N = 16 The maximum number of codes that can be allocated is 15, but individual terminals may receive a maximum number, K , of 5 10 or 15 codes. When the base station decides which users will receive data on the next frame, it also decides which channelization codes will be used for each user. ...
... A method as claimed in Claim 14, further comprising iteratively repeating the decoding process until each packet is correctly decoded or until the iteration number reaches a predetermined value. 16. ...
A method of transmitting data in a data transmission system having a plurality of channels, the method comprising: transmitting a first group of data at a first bit rate over a first group of one or more channels; and transmitting a second group of data at a second bit rate over a second group of one or more channels. The present invention relates t o base-station apparatus and a method of providing communication in multicode and multichannel systems. It is applicable, but by no means limited, t o Code Division Multiple Access {CDMA) and High Speed Downlink Packet Access (HSDPA) communication systems.
... Turbo-coded packets with a fixed Turbo code rate of , modulated with square −QAM schemes, assuming ≥ 2. Any of the source packets can be bit-wise XOR combined to produce a parity packet, from which extrinsic LLRs [13], [15] can be generated to improve soft decoding performance of the original source packets, where 2 ≤ ≤ . If − such XOR combinations are selected and performed from the packets to yield a punctured outer code rate of / for < ≤ 2 − 1, there exist 2 ( − ) − 1 sets of associated parity packets such that the bit-wise XOR combination of all packets in each set equals to zero. ...
... , . Unlike the approach in [15], this switching method is done in parallel for every source packet and will be terminated when the source packet is correctly decoded, which can be checked via coded cyclic redundancy algorithm. A modified log-MAP algorithm is outlined in [12] for the Turbo decoding process to produce the aposteriori LLRs as follows ...
... ⎠ , (14) from which Λ , ( ) is extracted to be switched with Λ ( ) at th external iteration, as explained in Section VI. Instead of running up to × groups of Turbo decoders to produce the external extrinsic LLRs as proposed in [15], only Turbo decoders are run in this proposed scheme at the same time to generate the external extrinsic LLRs in order to decode a similar number of parity packets, . Hence the number of iterations required is much smaller than that in [15] while system performance is maintained. ...
A two-stage coding scheme incorporated with a square M-quadrature amplitude modulation (QAM) scheme is proposed to realize multiple non-discrete data rates while reducing the packet error rate (PER) at small packet sizes. Subject to the intended code rate, Turbo-coded parity packets are generated through bit-wise XOR combinations of the source packets to provide additional soft information which can be produced, combined and shared by the Turbo decoder for each received packet to reduce the PERs.
... The effective data rates of these MCSs yield bit granularities of 0.5 and 1 bits per channel. In this paper, a novel MCS design aiming to realize bit granularities of 0.25 bits per channel is proposed which incorporate coded parity packet (CPP) codes [18] with Turbo codes and M -QAM schemes, where M = 4, 16, 64, and 256. ...
The residual energy in multi-code CDMA systems is not used to transmit any useful information and may increase up to the incremental energy multiplied with the number of multi-code channels. A two-group resource allocation scheme is developed to reduce this upper bound on the residual energy down to as low as a single-channel incremental energy, resulting higher energy utilization to improve the sum capacity. Since the incremental energy is the additional energy required to increase a data rate to a higher data rate by an additional amount called bit granularity, a new design of modulation and coding scheme based on the rate multiplication of outer and inner codes can be developed to produce different data rates such that the bit granularity is reduced, hence decreasing the incremental energy to further maximize the sum capacity. The two-group resource allocation scheme implemented with the proposed modulation and coding scheme is observed to have a 4 dB gain over the current HSDPA systems.
