Fiber Comes Home

Ikanos Communications bets that a copper link will be the biggest choice to reach the home. The company's line of fast DSL chip sets provides much higher performance than ordinary DSL chip sets. The Fx chip set is designed for use in BPON systems where the downstream termination is at an ONU which then communicates with the customer ONT by way of the standard local loop copper. The Fx 7030 chip set delivers up to 70 Mbits/s downstream and 30 Mbits/s upstream while the Fx10050 chip set provides 100 Mbits/s downstream and 50 Mbits/s upstream. Symmetrical speeds can be achieved at the lower rate in each chip. Both of these devices feature four ports as well as ATM Utopia level 2 and Ethernet (XMII) interfaces. These chip sets work in ONU, OLT, switches, routers and fiber concentrators.

The Fx10050S chip set is designed to work in the subscriber located equipment and features 100 Mbits/s downstream and 50 Mbits/s upstream or 50 Mbits/s symmetric. It works with the Fx7030 and the Fx10050. It has a built-in host for Ethernet applications. All of these devices have an integrated front-end (IFE) with integrated line driver, variable gain amplifier, low noise amplifier, related filters and other discretes that greatly minimize the need for external components.

While some companies are targeting the BPON, others are going after the international market for EPON. Passave is an example. Their initial target markets are in Japan and elsewhere outside the U.S. Already they have shipped tens of thousands of PON ports into the Asian market. Their primary products are the PAS5001 and PAS6001-B. The PAS5001 integrates an Ethernet Media Access Controller (MAC) with the EPON protocol management on a single chip. It is designed for CO OLT applications. Fully 802.3ah compatible, it supports up to 127 ONUs and features an ARM9 core with all the standard interfaces. It includes built-in 128-bit AES encryption. Their ONU reference design is shown in Figure 4.

The ONU side of the system can be implemented with the PAS6001-B. The interfaces include full duplex transmit and receive 1.25-Gbit/s TBI interface, full duplex 10/100 MII or 1000-Mbit/s GMII/TBI for connection to standard switch IC or PHY chips. Both chips feature programmable dynamic bandwidth allocation.

Centillium Communications is also addressing the EPON space. Its recently announced Colt chip is designed to implement the OLT at the CO in an EPON system. Centillium's Mustang chip targets the customer premises ONU boxes. Both chips are fully IEEE 802.3ah compatible and use an on-board MIPS processor. The Colt OLT features 802.1d bridging, 802.1q configurable VLAN, IGMP (Internet Group Management Protocol) for multicast and broadcast filtering, built-in encryption and decryption, and dynamic bandwidth allocation. The Mustang chip is for ONU customer boxes and includes the basic features of the Colt. It also features MII/GMII UNI ports. The clock and data recovery (CDR) and SERDES are also on-chip.

These protocol chips work with a transceiver chip like the Centillium Zeus or Apollo. The Zeus physical media device (PMD) is designed for point-to-multipoint operation and includes a fully integrated laser diode driver, limiting amplifier, a CDR for 155 and 622 Mbits/s and a dual quantizer. The data rate range is 125 Mbits/s to 1.25 Gbits/s. This burst mode device works with APON/BPON or EPON systems, in either OLT or ONU. It also features digital diagnostic monitoring compliant with the SFF-8472 standard. The Apollo chip is the PMD for point-to-point optical systems

Centillium's Unicorn chip is a broadband service processor (BSP) used to implement complete bridges or routers in customer premises equipment. Besides its fast MIPS processor, it also contains a DSP for voice-over-Internet-protocol (VoIP) operation. It supports four voice channels and has a TDM bus for PCM. The Unicorn has IPsec encryption in hardware as well as full DES, 3DES, and AES encryption . Software for packet header processing and IKE is provided. The chip includes two Ethernet 10/100 ports, USB, UART, GPIO, and SPI interfaces. All chips have standard EJTAG/JTAG support built in. The Apollo PMD is sampling now and samples of the Colt, Mustang, Unicorn, and Zeus are expected later in Q3.

The passive optical suppliers are also drooling over the prospect of a big PON rollout. Most already have splitter/combiner products that work but many are creating new devices for this potentially lucrative niche. While most splitters in PONs are expected to be fixed devices, Lynx Photonics Networks is betting that remotely controlled programmable splitters will have their place in the larger networks. By using static splitters, the network will be very inexpensive and highly reliable. Careful design is the key to selecting the split ratios and putting the splitters where necessary. This requires research and planning that may later prove to be different from reality as the system grows.

Demographic changes and fluctuating demand will make it tough to pin-point in advance just what the network should look like. Then as the demand grows, it may still be necessary to make changes, additions, and upgrades in the system, thereby offsetting much of the reason for the PON in the first place. Laying new fiber and making enhancements will be expensive and result in system down time not to mention the long provisioning time required. The new Lynx Photonics Networks programmable splitters will solve the problem.

The new Lynx LL-3560 is a remotely controlled and reconfigurable PON splitter that lets the carrier reconfigure a PON to fit constantly changing needs. By placing such devices at strategic locations within the network, like the CO or regional distribution center, the carrier can modify the light power distribution between the various branches of the network during a network build out. Provisioning becomes fast, easy, and inexpensive. The LL-3560 uses Lynx's Planar Lightwave Circuit technology with thermo-optical switches and splitters. Split ratios can be fine-tuned to 1% resolution.

It is anyone's guess where the PON trend will take us but I am optimistic. The traditional telecom carriers are definite ready for it as are the consumers who finally see the convergence. I predict a success here, over time. But the forthcoming broadband wireless access (BWA) business is developing quickly and we will see it as early as next year. I bet it will be only minimally competitive to PON but a real stimulant to the broadband field. BWA will fill a real need in the small towns and rural areas. Watch for my special report on the broadband wireless coming later this year.