Per Table 7 (page 31) of Mobile_WiMAX_Part1_Overview_and_Performance.pdf, the
maximal Power Amplifier output power at BS is 43 dBm, while it is 23 dBm for MS.
For IEEE 802.11, the maximal transmit power is 20 dBm, although I rarely see devices with power
larger than 15 dBm. The path loss model could be easily found in the literature and I shall
not provide it here.
I do not think changing modulation and coding scheme (MCS) is one of the major reasons
for wider coverage. Transmit power is one of the major reasons and there are some other
important factors had been mentioned by others. One thing that is missed is the length of cyclic
prefix (CP) on the design of an OFDM symbol. For IEEE 802.11, it is only 0.8 usec such that the
maximal delay spread could not exceed 0.8 usec and to operate outdoors. For IEEE 802.16e
(OFDMA), the CP length could be 12.8 usec for 8.75 MHz signal bandwidth with CP ratio = 1/8.
This CP length, alghough much larger than the one in 802.11, still limits its operating radius, when
comparing to DVB-T.
Hi all,
Thanks for the reply.
I would just to note that WiFi devices also is theorically capable to change coding scheme dynamically. That's why we could different WiFi bit rates (at least 11, 7, 5 1). Am I right?
I want to ask about some thing else: What's the most used TxPower for actual WiMax systems? Is there any implemented or theoritical propagation model so We could calculate coverage distances?
Best regrds
Ramzi TKA
On 11/20/06, Will Lee <will.lee@cosmobic.com> wrote:
Tx power is the most important and fundamental factor of coverage with a same carrier.
However, Wimax coverage performance lies in its power of changing modulation
and coding scheme dynamically. Moreover, there are other techniques
such as repetition, AAS.
----- Original Message -----
From: Ramzi Tka
To: STDS-802-16@listserv.ieee.org
Sent: Monday, November 20, 2006 4:18 PM
Subject: [STDS-802-16] WiMax coverage factors
Hi All,
Since WiFi and WiMax could use a same Physical Modulation (OFDM) and same coding schema (BPSK, QPSK,QAM), could we say that the factor that make WiMax coverage much more greater that WiFi coverage is the Tx Power?
Best Regards
Ramzi Tka
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