The HR/DSSS PHY is the upgraded physical layer defined by IEEE 802.11b which upholds data transfer at up to 11Mbps. HR/DSSS utilizes complementary code keying which divides the chip stream into a number of 8 bit code symbols. HR/DSSS utilizes the more limited 8 chip PN code, and this gives the higher rate of total codes per second. With the help of a higher rate of codes per second, the amount of resilience against interference is reduced. HRDSSS utilizes a mix of DQPSK and complementary code keying (CCK) for modulation.