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Industry's First OFDM-Based PLC Modem in the 10kHz to 490kHz Range Sets New Standard in Power Line Communication Performance

Maxim Integrated Products (PINKSHEETS: MXIM) introduces the MAX2990, an OFDM-based, power-line communication (PLC) modem.

Synopsis for Investor:

--  The MAX2990 is ideal for PLC applications requiring cost-effective,
    reliable, and secure long-range data communication over existing power
    lines. Examples include automatic meter management, building and industrial
    automation, and public safety systems.
--  This highly integrated SoC (system on a chip) enables robust data
    communication over the same electrical lines that supply power to other
    devices on the network. The MAX2990 dramatically reduces installation costs
    by eliminating the need for pulling new wires.
--  Maxim has solved the problems inherent to PLC. By applying advanced,
    broadband communication techniques, the MAX2990 provides robust data
    communication in the presence of narrowband interferers, group delays,
    jammer signals, impulsive noise, and frequency-selective attenuations.
--  Supporting a wide, 10kHz to 490kHz frequency range, the MAX2990
    complies with international power-line signaling regulations, including
    CENELEC, FCC, and ARIB.
    

This PLC modem employs advanced broadband-communication techniques to deliver cost-effective, two-way data communication over AC and DC power lines at speeds up to 100kbps. By using existing power lines, it reduces the need for external cables to interconnect between network nodes. Supporting a wide, 10kHz to 490kHz frequency range, the MAX2990 complies with international power-line signaling regulations, including CENELEC, FCC, and ARIB.

The challenge of communicating through existing power lines

The power-line network is by far the largest network in the world. While the idea of using power lines for communication goes back to the 1920s, the number of communication devices installed on dedicated wires far exceeds the number installed on AC power lines today.

Power lines are hostile environments. The lower, 10kHz to 500kHz frequency region is especially susceptible to interference, background noise, impulsive noise, and group delays. Figure 1 shows the average noise in a typical power-line channel.

To overcome these challenges, many companies have tried different modulation techniques such as spread spectrum and other narrowband schemes. None of these solutions achieved high data rates reliably over the long distances required by today's demanding applications.

OFDM and advanced networking technologies ensure robust data communication

Maxim has solved the problems inherent to PLC by applying advanced, broadband communication techniques. The MAX2990 uses OFDM technology with DBPSK modulation and forward error correction (FEC) to provide robust data communication in the presence of narrowband interferers, group delays, jammer signals, impulsive noise, and frequency-selective attenuations. Consequently, the MAX2990 is the industry's only broadband PLC chip that transfers data at the 10kHz to 490kHz frequency range.

Advanced networking techniques ensure a reliable, highly secure communications network. Specifically, a CSMA/CA scheme controls the data traffic flow in multiple-nodes distributed networks; an automatic repeat request (ARQ) function ensures the delivery and receipt of incoming packets. The MAX2990 also integrates a fast DES encryption/decryption coprocessor to enhance data security.

Improved bandwidth utilization maximizes data recovery

Figure 2 compares a narrowband technology, such as FSK, to a broadband technology, such as OFDM. These two technologies differ in the number of tones that each uses to transmit data per symbol (a symbol is the smallest unit of data transmitted at one time). The graph illustrates that OFDM uses bandwidth more efficiently than a narrowband method, thereby allowing more tones to be transmitted per a given bandwidth.

The higher number of tones available from OFDM systems enables the MAX2990 to implement data-recovery schemes such as Reed Solomon and convolutional encoding. These advanced channel-coding techniques provide error-correction bits that can be transmitted with the data on different tones to maximize data recovery. This OFDM capability makes the MAX2990 the industry's most robust PLC modem.

Superior performance at higher data rates

When evaluating a modem, one of the most significant values to consider is the bit-error rate (BER) at a given signal-to-noise ratio (SNR). The BER is the ratio of the lost bits to the transmitted bits at a certain noise level.

Whereas a typical FSK system has a BER of ~10-4 at 12dB SNR with a data rate of ~2kbps, the MAX2990 achieves the same BER at ~4dB SNR with data rates of ~32kbps in Cenelec bands between 10kHz and 95kHz. Thus, using OFDM technology with error-correction techniques enables an ~8dB improvement in performance at much higher data rates.

To further improve performance, the MAX2990 automatically switches to robust mode when input-signal variations exceed predefined thresholds, such as SNR levels, input-fluctuation levels, and potential in-band tone reductions. As a result, this mode achieves ~5dB improvement in SNR, but at lower data rates.

Samples and further information

The MAX2990 combines the physical (PHY) and media access control (MAC) layers in a single chip that also integrates Maxim's 16-bit RISC MAXQ® microcontroller. The MAX2990 includes 32kB of flash memory to run the MAC code and user-defined custom applications, plus 8kB of SRAM for data memory. Additionally, the MAX2990 supports UART, SPI(TM), and I²C serial interfaces for glueless communication between the power line and other devices on the network. See Figure 3 for details.

The MAX2990 is available in a 64-pin LQFP package and is fully specified over the -40 degrees Celsius to +85 degrees Celsius extended temperature range. Pricing starts at $8.50 (1000-up, FOB USA). For more information, visit: www.maxim-ic.com/PLC-Modem.

Maxim Integrated Products is a publicly traded company that designs, manufactures, and sells over $2 billion of high-performance semiconductor products annually. It was founded over 25 years ago with the mission to deliver innovative analog and mixed-signal engineering solutions that add value to its customers' products. To date, Maxim has developed over 5700 products serving the industrial, communications, consumer, and computing markets. For more information, go to www.maxim-ic.com.

MAXQ is a registered trademark of Maxim Integrated Products, Inc.

SPI is a trademark of Motorola, Inc.