doc.: IEEE /304 Submission September 16, 1998 AlantroSlide 1 Performance of PBCC and CCK Matthew Shoemake, Stan Ling & Chris Heegard

doc.: IEEE /304 Submission September 16, 1998 AlantroSlide 2 PBCC 64 state binary convolutional encoder Encoder requires 6 bits of memory Modulated onto QPSK, just like CCK

doc.: IEEE /304 Submission September 16, 1998 AlantroSlide 3 CCK CCK is an 8 bit in, 16 bit out block code CCK is rate 1/2, just like PBCC CCK is described by a generator over Z 4 G = [ ] (see doc )

doc.: IEEE /304 Submission September 16, 1998 AlantroSlide 4 Complexity CCK requires 26 adds per info bit PBCC requires 132 adds per info bit CCK requires 16 compares per info bit PBCC requires 64 compares per info bit

doc.: IEEE /304 Submission September 16, 1998 AlantroSlide 5 Bit Error Rate

doc.: IEEE /304 Submission September 16, 1998 AlantroSlide 6 Block Error Rate

doc.: IEEE /304 Submission September 16, 1998 AlantroSlide 7 Multipath 64 byte packets

doc.: IEEE /304 Submission September 16, 1998 AlantroSlide 8 Multipath, 1000 byte packets

doc.: IEEE /304 Submission September 16, 1998 AlantroSlide 9 What 3dB is worth Cell Size Increase An additional 3 dB coding gain equates roughly to a 30% increase in transmission distance in an open-air environment. For a given service area, the number of cells is roughly proportional to the service area divided by the transmission distance squared (area/  *distance ^ 2). With a 3dB gain, the area covered by a cell is 70% larger which means that the number of cells required is reduced to approximately 60% that of a standard FEC system for the identical service area. Reduced Power at the Client The user/network operator can configure the system to utilize the optional FEC for the access point to client transmission (AP -> C), the client to access point transmission (C -> AP), or both. One possible scenario is to use the optional, high-performance FEC for C -> AP transmission and the standard FEC for AP -> C transmission. Only the low-cost/low- complexity encoder of the optional FEC is implemented at the client, while the increased complexity and power of the high-performance decoder are consumed at the access point, where the power and complexity are not as critical. On the C -> AP transmission, the client may transmit at a lower power than the AP -> C transmission, yet still retain equivalent performance. The result is lower power consumption at the client, increasing the operating time at the point where it is needed.

doc.: IEEE /304 Submission September 16, 1998 AlantroSlide 10 What 3dB is worth (cont.) Greater Building Penetration An additional 3 dB coding gain allows the system to achieve transmission “through one more wall”. This again yields an increased cell size and more flexible cell/network planning. System Robustness in the ISM Bands New services are beginning to crowd the ISM bands utilized by the GHz wireless LAN standard. An additional 3 dB coding gain provides system robustness and operating margin against existing and emerging services within the 2.4 GHz ISM bands. Higher Network Throughput An additional 3 dB coding gain improves network throughput. First, an additional 3 dB coding gain improves the performance of marginal clients. Clients operating at a 30 ~ 40% packet error rate with the standard FEC can now operate at 10% PER with the optional high-performance FEC. Second, clients operating at 10% PER with the standard FEC can now operate at significantly lower PERs with the optional high-performance FEC. In either case, the overall throughput of the network will increase significantly.