101,866 research outputs found
Capacity of Cellular Wireless Network
Earlier definitions of capacity for wireless networks, e.g., transport or
transmission capacity, for which exact theoretical results are known, are well
suited for ad hoc networks but are not directly applicable for cellular
wireless networks, where large-scale basestation (BS) coordination is not
possible, and retransmissions/ARQ under the SINR model is a universal feature.
In this paper, cellular wireless networks, where both BS locations and mobile
user (MU) locations are distributed as independent Poisson point processes are
considered, and each MU connects to its nearest BS. With ARQ, under the SINR
model, the effective downlink rate of packet transmission is the reciprocal of
the expected delay (number of retransmissions needed till success), which we
use as our network capacity definition after scaling it with the BS density.
Exact characterization of this natural capacity metric for cellular wireless
networks is derived. The capacity is shown to first increase polynomially with
the BS density in the low BS density regime and then scale inverse
exponentially with the increasing BS density. Two distinct upper bounds are
derived that are relevant for the low and the high BS density regimes. A single
power control strategy is shown to achieve the upper bounds in both the
regimes. This result is fundamentally different from the well known capacity
results for ad hoc networks, such as transport and transmission capacity that
scale as the square root of the (high) BS density. Our results show that the
strong temporal correlations of SINRs with PPP distributed BS locations is
limiting, and the realizable capacity in cellular wireless networks in high-BS
density regime is much smaller than previously thought. A byproduct of our
analysis shows that the capacity of the ALOHA strategy with retransmissions is
zero.Comment: A shorter version to appear in WiOpt 201
On the capacity of wireless erasure networks
We determine the capacity of a certain class of wireless erasure relay networks. We first find a suitable definition for the "cut-capacity" of erasure networks with broadcast at transmission and no interference at reception. With this definition, a maxflow mincut capacity result holds for the capacity of these networks
Capacity of wireless erasure networks
In this paper, a special class of wireless networks, called wireless erasure networks, is considered. In these networks, each node is connected to a set of nodes by possibly correlated erasure channels. The network model incorporates the broadcast nature of the wireless environment by requiring each node to send the same signal on all outgoing channels. However, we assume there is no interference in reception. Such models are therefore appropriate for wireless networks where all information transmission is packetized and where some mechanism for interference avoidance is already built in. This paper looks at multicast problems over these networks. The capacity under the assumption that erasure locations on all the links of the network are provided to the destinations is obtained. It turns out that the capacity region has a nice max-flow min-cut interpretation. The definition of cut-capacity in these networks incorporates the broadcast property of the wireless medium. It is further shown that linear coding at nodes in the network suffices to achieve the capacity region. Finally, the performance of different coding schemes in these networks when no side information is available to the destinations is analyzed
Adaptive split transmission for video streams in wireless mesh networks
Wireless mesh networks hold great promise in the wireless transmission of video flows, particularly if the problem of providing sufficient network capacity can be addressed. For this reason, schemes which help to address this difficulty in capacity-limited wireless networks are of great interest. This paper presents a novel and simple algorithm, adaptive split transmission algorithm, for achieving real-time, and quality-guaranteed video transmission in wireless mesh networks. The algorithm utilizes the unused capacities of multiple channels rather than trying to transmit the flow over just one overloaded channel. The flow is efficiently split into several sub-flows in a capacity-aware manner, each sub-flow then being transmitted through different channels in parallel. The adaptive split transmission algorithm controls flows dynamically in response to changes in the states of the available channels, thereby avoiding the overloading of any one channel. We evaluate the algorithm through simulations. The results show that the adaptive split transmission algorithm achieves synchronized, quality-guaranteed, and real-time wireless video transmission. The proposed algorithm can be used for interactive real-time wireless video applications without changing current wireless hardware, MAC protocols and upper-layer protocols
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