A transparent MAC method for bandwidth sharing and CDV control at the ATM layer of passive optical networks

Abstract

Absstract-In the quest for a way to bring local loop costs down and make B-ISDN affordable to small traffic customers, the passive optical networks (PON's) in combination with ATM (APON's) have been investigated extensively. To achieve the required medium sharing on a time division multiplexing (TDMA) basis, an arbitration mechanism is required in the upstream direction. The resulting multiplexing and concentration, though it is the source of significant savings, it has been plagued by the penalty of high distortion of the traffic profiles at the exit of the PON. The preventive congestion control method of ATM is rather intolerant of such distortions in the multiplexing stages. Arbitration methods which are either semistatic or based on number of arrivals per reservation period, cause very high cell delay variation (CDV). The cell clustering introduced by the arbitration method cannot be distinguished from peak rate violations of the contract by the policing unit. The result is either unwarranted rejections of conforming cells or unacceptably low utilization. The scheme presented herewith maintains a CDV behavior comparable to that of a common centralized FIFO multiplexer. It relies on a meticulous recording of the arrival timing of cells enabling a subsequent allocation of slots which produces almost the same output (and CDV) as the centralized FIFO multiplexer. A compact coding of the timing information restricts bandwidth waste for control information to the size found in other similar protocols. The most important feature is that the scheme is amenable to easy hardware implementation and does not require any call related information.

<title>New wavelength assignment schemes for wavelength division multiplexed passive optical networks</title>

“…When distribution of permits takes place, this mechanism allows priority to be given to cells that arrived earlier in the frame. This method was first reported in reference 19 and has recently been adapted for a G.983 frame for a system with different quality of service classes 17 . The latter proposes a frame divided into eight segments, the first five containing 7 time slots (equal to the transmission period of one ATM cell) and the last three of 6 time slots, to give a total of 53.…”

Multiple access schemes for Ethernet Passive Optical Networks (EPONS)

“…Since different ONUs in an APON share the upstream channel to deliver data to the OLT, many research works are focused on the MAC protocols used for the upstream data [11][12][13][14][15][16]) as follows.…”

“…The order of transmissions is determined by the management procedures. To address the performance of Cell Delay Variation (CDV), [12] focuses on the design and implementation of a MAC mechanism emphasizing a very low CDV. It relies on a meticulous recording of the cells arrival time that enables a subsequent allocation of time slots, thus producing almost the same output and CDV performance as the centralized FIFO multiplexer.…”

“…In order to emulate the above multi-queue polling system, let us recall the principle of the BGP scheme. In BGP, the OLT can be regarded as the central server to cyclically poll multiple ONUs for upstream transmissions with the order decided by the Entry Table and the superfluous transmission windows, the number of entry occupied by a non-BG ONU can be approximate to n according to formula (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). Then the arrival rate for the queues represented by the whole entries remained in the Table will be /…”

A bandwidth guaranteed polling MAC protocol for Ethernet passive optical networks

“…APON was developed and defined initiatively as a PON-based optical access network that uses ATM as its layer 2 protocol. There are a numbers of proposals for APONs to share upstream bandwidth [3][4][5]. However, the expense and the complexity of an APON have made it to a declining interest of industry.…”