This paper proposes an extended M-sequence/extended perfect difference (EMS/EPD) code family which can be applied to a two-dimensional (2-D) spectral/spatial (SS) fiber-optic code division multiple access (FO-CDMA) passive optical network (PON) with interference elimination. In addition, the proposed code family can effectively suppress the effect of phase-induced intensity noise (PIIN) and has a flexible size and the cyclic property. By using an extending technique, the number of fibers is substantially reduced between the remote node (RN) and the optical network units (ONUs). Furthermore, we design a compact optical line terminal (OLT) using the arrayed waveguide grating (AWG) router at the central office (CO) and simple ONUs using the thin-film filters (TFFs) at end users. Based on the mathematical analysis and numerical results, the 2D SS EMS/EPD code family is suitable for high-rate transmission with very good performance.

In this article, the super perfect difference (SPD) code family is presented and used in the compact spectral amplitude code (SAC) optical code-division multiple-access (OCDMA) passive optical networks (PONs). Based on the excellent properties of the SPD, such as low in-phase cross correlation (IPCC) value, cyclic shift, and excellent orthogonality, we design the SAC OCDMA PON which consists of a compact optical line terminal (OLT) and many simple optical network units (ONUs). Accordingly, the proposed PON not only can accommodate a large number of simultaneous users but also has compact configuration and good bit error rate (BER) performance with moderate security.

This paper describes a novel sigma-delta fractional-N synthesizer architecture with fractional spur and quantization noise cancellation which eliminates loop bandwidth limit in traditional fractional-N synthesizers. The proposed synthesizer utilizes a delay line after the reference signal to compensate phase errors and achieves at least 19dB fractional spur and quantization noise improvement if a delay line with 32ps delay resolution is employed in the phase-locked loop with 180kHz loop bandwidth at 3.5GHz synthesized frequency. The improvement can be further enhanced with advanced process with the improved delay resolution.

In this paper, a new code family named partitioned partial prime (PPP) code is proposed for high-rate spectral amplitude code (SAC) optical code-division multiple-access (OCDMA) passive optical networks (PONs) applications. They are derived from the well-known prime codes (PCs) and a manner of partitioning technique. To minimize in-phase cross-correlation (IPCC), we employ the partial and padding schemes. In addition, the influences of both phase-induced intensity noise (PIIN) and shot noise are further mitigated by the partition and two-code keying (TCK) schemes. The PPP code family has the property of good code balance, flexible code length, and excellent orthogonality. The numerical results show that the proposed system using PPP codes can substantially accommodate a lot of maximum and simultaneous users with high-rate transmission and low bit error rate (BER).

This paper presents a novel differential coding method for the symmetrically differential polarization shift-keying system. The proposed differential coding method, which can overcome the slow polarization variation in the fiber, constructs the reference frame by setting the sum, the difference, and the cross product of previous two symbols as the first, second, and the last axes of the signal space. Obviously, each axis is determined by the previous two symbols together. Thus, at the receiver, the new scheme constructs a noisy reference frame more accurately than other schemes and yields better performance. The optimal constellation for the system is symmetric and easy to find. The analytical integral form for the bit error rate (BER) of the proposed system is derived, and the saddle point method is applied to obtain the analytical results. It is found that the performance in terms of BER is much better than that of other differential polarization shift-keying systems. The analytical results agree with the simulation very well.

The physical layer side information is employed to improve the throughput of the hybrid-II ARQ protocol in the binary phase shift keying wireless communication system. With the combination of the hybrid-II ARQ and the n-bit-marked error correction scheme, the packet throughput is improved significantly. The numerical examples show that the throughput of this combination scheme may have a maximum gain about 0.26.

A novel asynchronous transfer mode (ATM) switching fabric using three-dimensional optical code division multiple access (CDMA) technology is presented. The proposed three-dimensional codes, temporal/spatial/wavelength (TSW) codes, have out-of-phase autocorrelation and cross-correlation equal to zero and one, respectively. Spectral slicing technology is utilized to achieve wavelength encoding and decoding. The results show that the switching fabric has no internal blocking and the number of input/output ports can reach up to 1369. The cell loss without considering the output blocking is smaller than 10/sup -8/. The total throughput can be as large as 1.1 Tbit/s.

The performance of frequency-hopping multiple-access systems with side information and binary frequency-shift keying signaling is evaluated. The side information is generated by Viterbi's ratio threshold test (RTT). Both synchronous and asynchronous hopping systems over fading channels are examined. The system with RTT side information performs significantly better than that with perfect side information or hard decision. Compared with hard decision, the RTT side information provides more than 20% improvement in capacity for E/sub b//N/sub 0/=10 dB over Rayleigh channels. Also, we find that the optimum threshold in the RTT scheme should be dynamically adjusted with the number of simultaneous users in the system.

A study of the multichannel coherent CPFSK communication system employing Reed-Solomon codes is reported. The crosstalk between adjacent channels, the impact of the laser phase noise, and selection of the optimum code rate are investigated. By applying a suitable coding scheme, the laser linewidth can be greatly relaxed, and the receiver sensitivity will be remarkably improved. A 100 Mbit/s system is used to verify the coding benefit. The results show that the impact of the laser linewidth can be largely alleviated by applying a (255, 223) Reed-Solomon code. When the linewidth is fixed (/spl Delta//spl nu/T=2%), this code can improve the receiver sensitivity by more than 15 dB.

A detailed analysis of optical coherent phase diversity single-filtered and dual-filtered frequency-shift keying (FSK) receivers corrupted by shot and phase noise is presented. With delay and cross-product detection, the effect of various parameters, including bandwidths of filters, delay time, frequency deviation and noises, are investigated. The tolerance of phase noise is quite large, when small time delay in the demodulator and appropriately large frequency deviation is selected. It is also shown that there exists an optimal bandwidth for the first filter in the dual-filtered FSK receiver. For a total linewidth equal to half of the bit rate, the power penalty incurred (at BER=10/sup -9/) is 1.92 dB when the modulation index is 4, provided that an optimal filter bandwidth and a frequency deviation-delay product of 0.25 are used.>

This paper concerns scheduling parallel programs in multiprocessing systems. The goal is to improve the job turnaround time and speedup. As most programs are not fully parallelizable, parallel programs consisting of serial, partially parallel, and (perfectly) parallel stages, are modeled by task graphs which depict the parallelism profiles. In another perspective, the study is intended to be a queueing counterpart of Amdahl's Law. Various two-stage cases are investigated with FCFS or priority scheduling policies and the optimal strategy is determined. Results indicate that, with nonhomogeneous parallelism profiles, it would be a better processor allocation policy to give a preferential treatment to serial stages. The study might hopefully improve the design of parallel operating systems as well as parallel algorithms, databases, and parallelizing compilers.

Addition of a second bus is proposed to provide high bandwidth as well as reliable service for token-passing-bus LANs. The second bus proposed is normally used for reservation so that the token on the data bus is dynamically passed to ready users for packet transmission. Furthermore, it takes the place of the data bus when the data bus fails. A reservation token-passing protocol is used which not only is collision-free but also minimizes the token-passing delay. An analysis of this dynamic token-passing protocol includes both analytical and simulation results.>

The authors analyze the performance of interconnected CSMA/CD (carrier-sense multiple-access with collision detection) LANs. The interconnection system consists of a packet-switch node which interconnects numerous sections of local area networks operated in unslotted nonpersistent CSMA/CD mode. Each of the CSMA/CD networks has a finite number of users. The authors assume that the sections of LANs interconnected are homogeneous and they all have the same number of users attached. A detailed modeling technique of the system using continuous-time Markov chain is explored. The state-transition-rate diagrams of each of the CSMA/CD networks are investigated. The system throughput and delay are also studied. Numerical calculation and simulation of both throughput and delay are provided.>