Table 1 Frequently used notations

N _R

Set of RS

N _M

Set of MS

r

Relay station

c

MS

N _r

MS associated to relay r

r _max

Relay station with the largest number of MS

μ _{b, c} (t), μ _{r, c} (t)

Variables that indicate the activation of link (b, c) and (r, c)

p _{b, c} (t), p _{r, c} (t)

Success probability on link (b, c) and (r, c)

p _{b, c} , p _{r, c}

Averate success probability on link (b, c) and (r, c)

Ω

Feasible region of active links

a _c (t)

Arrival rate of c at time t

λ _c

Arrival rate of c

q _{b, c} (t), q _{r, c} (t)

Queue size of MS c at BS and RS

s _{b, c} (t), s _{r, c} (t)

Transmission state of packet of the MS c at the end of time slot t