Reconfigurable Baseband Processing for Wireless Communications - Adaptive Signal Processing in Wireless Communications - page 447

GPP DSP FPGA FPGA

GPP DSP FPGA FPGA

Mon t ium Mon t ium Mon t ium

ASIC

Mon t ium Mon t ium

Montium ASIC

FIgure 15.3 The Chameleon SoC template.

all parts of an algorithm can run on a processing part on which it can be implemented
most efficiently. The ideas above translated into the definition of the Chameleon SoC
template. This template is illustrated in Figure 15.3.
A Chameleon SoC that contains sixteen processing tiles is depicted. The black grid
in the figure represents the NoC. The Chameleon SoC attempts to combine the best
of all worlds: the performance and energy efficiency of ASICs, the bit-level flexibility
of FPGAs, the domain-specific flexibility of the Montium and DSPs, and the general-
purpose applicability of GPPs. Information exchange between the different tiles is real-
ized by means of the NoC.

15.2.4 Network-on-Chip
A key element within the Chameleon SoC template is the NoC. In a NoC, a processing
tile is connected to a router. Routers of different processing tiles are interconnected.
Communication between two processing tiles involves at least the two routers of the
corresponding processing tiles, but other routers might be involved as well. A NoC that
routes data items in a SoC has a higher bandwidth than an on-chip bus, as it supports
multiple concurrent communications. The well-controlled electrical parameters of an
on-chip interconnection network enable the use of high-performance circuits that result
in significantly lower power dissipation, shorter propagation time, and higher band-
width than is possible with a bus (see also [ 52 ]). To describe the network traffic in a
system, multiple types are identified [22]. According to the type of service required, the
following types of traffic can be distinguished in the network:

• Guaranteed throughput (GT) is the part of the traffic for which the network has

to give real-time guarantees (i.e., guaranteed bandwidth, bounded latency).
Best effort (BE) is the part of the traffic for which the network guarantees only •

fairness but does not give any bandwidth and timing guarantees.