Jiajun Ye

Theoretic and experimental study on mm-wave radio over fiber system based on OFM

This paper presents an overview on millimeter wave radio over fiber systems based on millimeter wave generation by optical frequency multiplication (OFM). The disadvantage of original OFM technique is checked and a novel bi-directional mm-RoF system based on new OFM technique using dual-drive MZM as high-order optical side-modes generator is proposed in principle and experimentally verified by a bi-directional mm-RoF system which not only produces 38 GHz information bearing signal in downstream, but also provides 40GHz local reference for down-conversion of upstream signal. Finally the advantage of OFM technique in reducing fading effect of fiber dispersion is theoretically proved.

Performance analysis of flat optical comb generation based on recirculating frequency shifter

The performance of the optical frequency comb generation based on the re-circulating frequency shifter has been analyzed and demonstrated in this paper. We have theoretically analyzed the condition for flatness of the optical frequency comb and the relative intensity noise influence. And the resulting performance analysis has been confirmed by a successfully generated 16 comb lines, which are stable and flat with spacing 12.5 GHz.

Theoretical and experimental study of mm-wave RoF/wireless system based on OFM technique with OFDM modulation

This paper introduces a new bidirectional mmRoF system based on optical frequency multiplication (OFM) scheme using dual drive Mach-Zehnder Modulator (DD-MZM) and OFDM modulation. The emphasis is put on the optimization of optical modulation index to the MZ intensity modulator for OFDM signal with high PAR which imposes a limitation on the system bit error rate (BER) performance due to the nonlinearity of the MZ modulator. The theoretic analysis on carrier to composite triple beat ratio is performed. The extension to system BER for QAM format is presented and the experimental proof is given in a 40 GHz mmRoF system.

Experiment demonstration of a bi-diretional millimeter-wave over fiber system based on OFM and SBS amplification

The experimental result of a bi-directional millimeter-wave over fiber system based on OFM by using Dual Drive MZM as side-modes generator is given in this paper. The selective amplification by SBS makes the output frequency tunable.

PWFQ : A priority-based weighted fair queueing algorithm for the downstream transmission of EPON

In the downstream direction of EPON, all ethernet frames share one downlink channel from the OLT to destination ONUs. To guarantee differentiated services, a scheduling algorithm is needed to solve the link-sharing issue. In this paper, we first review the classical WFQ algorithm and point out the shortcomings existing in the fair queueing principle of WFQ algorithm for EPON. Then we propose a novel scheduling algorithm called Priority-based WFQ (PWFQ) algorithm which distributes bandwidth based on priority. PWFQ algorithm can guarantee the quality of real-time services whether under light load or under heavy load. Simulation results also show that PWFQ algorithm not only can improve delay performance of real-time services, but can also meet the worst-case delay bound requirements.

Single Bit Burst Synchronization Technology and Its Application

Synchronization technology is one of the key technologies in high speed digital communication systems. The bit rate of an EPON system reaches 1.25 GB/s. The receiver in OLT must work in burst mode. Traditional phase-locked-loop technology can not work perfectly in this case and other burst synchronization technologies may be either difficult or expensive to realize such function. In this paper, a Single Bit Burst Synchronization (SBBS) technology, which solves the problems mentioned above, is presented. Because this method gives up the key words detection, it is independent of the protocol used. So it can be used in any PON systems, such as Ethernet PON, ATM-PON, etc. In order to analyze the performance of SBBS technology, we implement a 1.25 GB/s EPON burst receiver as an example, and the results of computer simulation are also provided.

A fair scheduling algorithm based on sliding window mechanism for EPON

In implementing EPON systems, one of key challenges is designing bandwidth scheduling scheme to achieve network efficiency and meet various QoS requirements. This paper proposes a novel scheduling algorithm over EPON based on sliding window mechanism, which divides a transmission circle into two sections and introduces bandwidth sliding window substituting for the conception of fixed maximum window. Computer simulation results show that the performance of the proposed algorithm is effectively improved in terms of packet delay and upstream channel utilization.

Design and FPGA implementation for MAC layer of Ethernet PON

Ethernet passive optical network (EPON), which represents the convergence of low-cost, high-bandwidth and supporting multiple services, appears to be one of the best candidates for the next-generation access network. The work of standardizing EPON as a solution for access network is still underway in the IEEE802.3ah Ethernet in the first mile (EFM) task force. The final release is expected in 2004. Up to now, there has been no standard application specific integrated circuit (ASIC) chip available which fulfills the functions of media access control (MAC) layer of EPON. The MAC layer in EPON system has many functions, such as point-to-point emulation (P2PE), Ethernet MAC functionality, multi-point control protocol (MPCP), network operation, administration and maintenance (OAM) and link security. To implement those functions mentioned above, an embedded real-time operating system (RTOS) and a flexible programmable logic device (PLD) with an embedded processor are used. The software and hardware functions in MAC layer are realized through programming embedded microprocessor and field programmable gate array(FPGA). Finally, some experimental results are given in this paper. The method stated here can provide a valuable reference for developing EPON MAC layer ASIC.

High-speed burst synchronization in Ethernet PON system

Synchronization is one of the difficult problems in realization of Ethernet PON receiver, because the bit rate is as high as 1 .25Gb/s and the receivers works in burst mode. Burst mode synchronization relates to two key techniques: ranging and phase adjustment. For these two key techniques, this paper puts forward a ranging flow for the Ethernet PON system and a novel burst mode synchronization circuit running at 1.25Gbps. Using VHDL, the algorithm and the structure of ranging could be realized, and the result of simulation is provided. The performance of the ranging flow is compared for the different collision resolution algorithm. At the same time, the feasibility and the performance of a high speed burst synchronization circuit are presented with the simulation result.