This paper investigates a newly proposed spreading code-set based on the prime code (PC) families referred to as ‘transposed modified prime codes (T-MPC)’ for the enhancement of spectral efficiency of synchronous incoherent optical code-division multiple-access (OCDMA) networks. This code family increased the code-set cardinality up to twice of existing PC families’ size. This also implies that...

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Implementable rake receivers have less correlators than there are propagation paths in the channel. In the case of slowly time-variant channels the rake receiver is able to adapt to the channel by selecting the paths with the maximum momentary power [Gue92a, Gue92b]. In practice, it is not possible to select the best paths for every modulation interval. The bit error probability of rake receive...

Typical receiver processing, targeting always the best achievable bit error rate performance, can result in a waste of resources, especially, when the transmission conditions are such that the best performance is orders of magnitude better than the required. In this work, a processing framework is proposed which allows adjusting the processing requirements to the transmission conditions and the...

| This paper examines the peformance of turbo-codes with non-identical component codes. We show that asymmetric turbo-codes provide good performance with respect to both the \erroroor" and the \pre-erroroor" regions of the bit error rate

In this contribution the family of generalized multicarrier DS-CDMA (MC DS-CDMA) schemes [1] is investigated, when considering time-domain half-sine and raised-cosine chip waveforms, in addition to the rectangular chip waveform. Our results show that for a given subcarrier spacing the particular choice of the chip waveform has a substantial influence on the system’s performance. However, in the...

Abshacf-The lack of representativeness in the existing analysis concerning the problem of estimation of bit error rates for narrowband digital communications in the presence of atmospheric burst noise, arising due to the omission of consideration of the structure and time parameters of the noise bursts, is emphasized. A method of analysis in which these parameters can suitably be introduced is ...

あらまし 高速信号伝送が要求される次世代の移動無線通信では周波数選択性フェージングチャネルの克服が必 要不可欠であり,マルチキャリア符号分割多重アクセス(MC-CDMA)が注目されている.伝送特性を改善する技術 としてアンテナダイバーシチが良く知られている.筆者らはこれまでに送信側にチャネル等化処理を集中できる時 空間符号化送受信ダイバーシチ(STBC-TRD)を提案した.STBC-TRD は,送信チャネル情報を用いて送信信号を符 号化し,受信側で簡単な復号操作を行うことによりダイバーシチ効果を得ることができる.しかし,これまでの提 案では受信アンテナ数が 2 本までに制限されていた.本論文では,4 アンテナ受信を可能とする送信符号化を提案 している.そして,このときの BER 特性を計算機シミュレーションによって明らかにしている.また,時空間符号 化送信ダイバーシチ(STTD)と受...

あらまし−最近,高速移動無線アクセス技術としてマルチキャリア符号分割マルチアクセス(MC-CDMA)が注目さ れている.MC-CDMA では最小平均二乗誤差 (MMSE)規範に基づいた周波数領域等化(FDE)により厳しい周波数選 択性フェージング環境下においても優れたビット誤り率(BER)特性を得ることができる.従来の周波数領域等化で はブロック間干渉を避けるためにガードインターバル(GI)の挿入が必要であるが,GI 挿入によって伝送効率が低下 してしまう.GI 挿入を必要としない周波数領域等化(Overlap FDE)を用いることにより伝送効率の低下を防ぐことが できる.更に伝送特性を改善する技術として最近,時空間ブロック符号化送信ダイバーシチ(STTD)が注目を集めて いる.従来の GI 挿入を用いる FDE は STTD 復号と容易に組み合わせることができ,優れた BER 特性...

We consider source requantization in tw oforms | successive degradation (i.e., source delity reduction) and bit stealing (i.e., information embedding) | when no forward planning has been done to facilitate the requantization. We focus on nite-alphabet sources with arbitrary distortion measures as well as the Gaussian-quadratic scenario. F orthe successive degradation problem, w e show an ac hie...