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Copyright 2009
Dr. Wolf Wireless GmbH 
All Rights reserved

History
The research work of many years in the area of coding technique lead to many important results for the development of modern wireless solutions / systems. Among these research activities CCF (Cross Correlation Function) procedure was produced. The CCF-procedure, originally designed for the application in ATM-Networks is exactly the coding which is applied to the OQPSK modulation according to the IEEE standard 802.15.4V2003.
On the basis of the CCF procedures the technology PSSS (Parallel Sequence Spread Spectrum) was developed. This document describes the basic principles of PSSS and its multipath fading resistance.

Key Challenges of Today's RF World
Today's RF technologies provide largely unbalanced answers to a divergent set of requirements. Key challenges in RF communications are today:
Range:
To maximize the coverage for Tx power permitted / chosen.
Non line of sight environments:
To transmit reliably in non line of sight environments with multipath fading.
Interference:
To operate under disturbances both through human made and atmospheric noise.
Coexistence:
To minimize disturbance of other RF systems.
Efficiency:
To offer efficient use of the RF spectrum. To be efficient in power consumption. To be efficient in physical implementation.

Today's RF technologies
MPSK, QAM, OFDM etc. Features: High single-station throughput, high specific and absolute data rates, efficient use of RF spectrum.
Disadvantages: Low range, susceptible to interference, complex & fragile in implementation, sensitive to multipath fading (except OFDM).

High power consumption (especially OFDM).

DSSS, O-QPSK Features: Processing gain provides better range and robustness against interference. Disadvantages: Low specific data rates, not efficient in use of spectrum, limited throughput in existing bands. 

FHSS. Features: Robust against multipath fading, good coexistence with other networks based on same or other RF technology. Disadvantages: High effort for management of hopping, inherits issues of underlying modulation, not suitable for high-throughput systems, decreasing data rate caused by multipath fading.
Combinations of technologies in today's RF communication standards mitigate the problems and extend applications, but do not solve the underlying issues.
Most of the consumer wireless applications are based on wireless technologies, such as Bluetooth, OFDM (WLAN) etc., operating in specially allocated, license free, frequencies (ISM bands) which have limited capacity (bandwidth). As more wireless applications utilize the same bands their efficient use of the frequency spectrum is essential to provide the increasing number of users with higher data transmission speeds, more robustness, better range-coverage at a lower price tag of the wireless IC and sub-system. OEM, IC manufacturers and standardization groups (IEEE, ZigBee, WiFi etc.) have been searching for new wireless technologies and solutions which can overcome these challenges and limitations.  
Demand indicates that high data rate applications (like WLAN, audio and video) will mainly operate in the higher 2.4 and 5.8 GHz bands, resulting in higher interference in these bands. Therefore OEMs and the IEEE standards committees have realized the advantage of the Sub-1GHz band (868/915MHz) for low power applications such as sensor, monitoring & control or active RFID. China and other Asian countries have announced their intention to open new license free Sub-1GHz bands in 2006. Traditional radio technologies and RF IC designs, current wireless chips cannot offer high data rates, more than 20/40Kbit/s, in the Sub-1GHz band. Due to high frequency physics 2.4GHz band technologies are not able to provide better coverage with the result that OEMs are asking for wireless solutions which can provide both the advantage of greater coverage and higher data transmission speeds at lower complexity (cost).
With the introduction of PSSS (Parallel Sequence Spread Spectrum) technology the transmission efficiency can be increased by a factor of up to 10, with highest multi path robustness and extended coverage/range of existing wireless solutions by a multiple factor. The enhancement of the PSSS technology is the base for the unique link budgets at 250 kbps of our PSSS based IEEE802.15.4-2006 platform. The enhanced performance is even the reason for very low PER in multipath fading environments. Fore more details lo
ok on products and the presentation here.