Chapter 1: Product description Wireless
operation
Page 1-15
TDD frame parameters
The TDD burst duration varies depending on the following:
Channel Bandwidth
Cyclic Prefix
Frame Period
Frame configuration - Downlink Data
Link operation – Dynamic Rate Adaptation
OFDM and channel bandwidth
The PMP/PTP 450 Platform Family transmits using Orthogonal Frequency Division Multiplexing
(OFDM). This wideband signal consists of many equally spaced sub-carriers. Although each sub
carrier is modulated at a low rate using conventional modulation schemes, the resultant data rate
from the sub-carriers is high. OFDM works exceptionally over a Non-Line-of-Sight (NLoS) channel.
The channel bandwidth of the OFDM signal is configurable to one of the following values: 5, 7, 10,
15, 20 and 30 MHz. Higher bandwidths provide greater link capacity at the expense of using more
bandwidth. Systems configured for a narrower channel bandwidth provide better receiver
sensitivity and can also be an appropriate choice in deployments where the amount of free
spectrum is limited.
Note
The channel bandwidth must be configured to the same value at both ends of the link.
Not all channel bandwidths are available in all regulatory bands.
Cyclic Prefix
OFDM technology uses a cyclic prefix, where a portion of the end of a symbol (slot) is repeated at
the beginning of the symbol (slot) to allow multi-pathing to settle before receiving the desired
data. A 1/16 cyclic prefix means that for every 16 bits of throughput data transmitted, an additional
bit is used. For your convenience, the 450 Platform Family ODUs have been locked to a 1/16 CP.
Frame Period
The frame period or frame duration is the time between the beginning of a frame and the end of
the frame. The 450 Platform Family supports two frame periods: 2.5 ms and 5 ms.
Note
PMP 450m AP supports 2.5 ms Frame Period only.
Summary of Contents for PMP 450 Series
Page 125: ...Chapter 3 System planning Typical deployment Page 3 3 Figure 37 Wall installation...
Page 126: ...Chapter 3 System planning Typical deployment Page 3 4 Figure 38 Roof installation...
Page 127: ...Chapter 3 System planning Typical deployment Page 3 5 Figure 39 GPS receiver wall installation...
