As shown in Figure 2, ICT is an ASIC/core solution that integrates into the modem of the baseband chipset. When deployed in the handset to mitigate forward link interference, no other components and no re-design of the handset RF are required, resulting in no form factor changes to the handset. Furthermore, no base station modifications are required.

The sequence of signal-processing steps in ICT occurs after RF processing, delivering interference-cancelled signals to the RAKE receiver. ICT delivers a subspace version of the original path signals to each finger, relatively free of ISI and ICI, with higher SINR. This is illustrated in Figure 3.

ICT has been integrated into platforms and successfully tested in the field on commercial networks. In addition to developing the basic ICT algorithms, TensorComm has evolved a process for integrating its algorithms and intellectual property into a customer's CDMA or WCMDA modem.

In a CDMA network, as traffic load increases, the total base station transmit power increases, because a handset requires more transmit power from the base station to maintain the same performance in dense interference. The effect on the network is that probability of coverage decreases and network performance degrades. Furthermore, when the network load exceeds 75%, degradations are more pronounced as cell boundaries collapse, creating coverage holes. The result is that customers experience a greater number of dropped and blocked calls.

The sequence of panels in Figure 4 demonstrates in a qualitative way how ICT reclaims power and spectral efficiency to maintain cell coverage and traffic density. That is, interference cancellation increases the capacity of the network for more users or for higher data rates, while expanding or maintaining network coverage. In essence, it shows that base stations no longer have to transmit so much power to each handset. And can use extra power to increase capacity, coverage, data rates and quality.

A network attempts to maintain uniform quality for users by setting performance targets and adjusting transmit power to meet these targets.

At a low level, ICT operates in tandem with fast and slow power control to provide performance improvement. ICT improves SINR on each signal, which translates to a reduction in demodulation errors and lower frame error rate (FER). Accordingly, the handset compensates for this performance improvement by requesting a lower forward-link transmit power in an attempt to keep base station transmit power at a minimum.

Additionally, the increase in SINR due to interference cancellation allows a greater number of base station sectors to remain in the active and candidate sets. This provides greater signal diversity, which is invaluable in compensating for signal fading. The technology can provide large instantaneous gains in fades that would limit handset performance. The interference cancellation gains also “soften” the impact of fades, since power control movements are minimized during fades.

From the base station perspective, each ICT-enabled handset requires reduced transmit power to maintain the same performance. As a result, the base station is able to increase the number of served users in a cell. From the network, a second-order effect is observed: for a given number of users, each base station lowers the transmit power for ICT-enabled handsets, reducing the noise on all mutually interfering sectors. This leads to further reduction in network transmit power.

In field environments, there is almost always an opportunity for interference cancellation. As a result, ICT will be operational for much of the time. However, the design incorporates a level of intelligence, so that it may turn off the cancellers when cancellation is not beneficial. This “no-harm” feature guarantees that an enabled handset always provides performance better than or equal to that of a non- ICT-enabled handset.

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