In addition, assume a predefined HCCA transmission
opportunity duration tTXOP(li,j) for each link li,j, with total 1 i j ?? ?‰¤ < , and a link adaptation
mechanism at the physical layer that can operate at an MSDU granularity. The end-to-end
6 We assume that the MSDUs of each flow are accommodated with an independent queue at each link.
Cross-layer Optimized Video Streaming over Wireless Multi-hop Mesh Networks
113
cross-layer optimization which determines the chosen path (routing), the maximum MAC
retry limit, and the chosen modulation (at the PHY layer) for the transmission of each
MSDU is:
{ } { } total
,
max*
, ,,expected , 1
: , , ( ) arg max min ( ) i
i ij i i
i ij ij v l j
v ml cl
??
??—
??? ??? ??? ??? ?‰¤ <
??® ??? ??? ?¤ = ?‹… ??† ??? ??? ??? ??? ??° ??» p p p
p
P
(12)
where:
[ ]max
,expected 1 ( ) i
i v v v e L ?¤ ??® ??? ??† = ??’ ?‹…??† ??? ??? ??° ??»
p
p (13)
with ( ) i v e L p given by (7), max
i ?¤p the maximum number of retransmissions for MSDU v if
scheduled via path pi, and c(li,j) corresponding to the remaining time interval for which link
li,j can support the video-flow traffic under HCCA. For the transmission opportunity
intervals belonging to the current service interval tSI, c(li,j) can be calculated as:
SI
, TXOP, queue, ( ) max ( ) ( ),0 i j i j i j
t
c l t l d l
??± ??? ??? ??? ??? ??? = ??’ ??? ??? ??? ??? ??? ??? ??? ???
??‘ .
Pages:
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320