4,824 research outputs found
Transmission capacity of wireless ad hoc networks with successive interference cancellation
IEEE Transactions on Information Theory, 53(8): pp. 2799-2814.The transmission capacity (TC) of a wireless ad hoc
network is defined as the maximum spatial intensity of successful
transmissions such that the outage probability does not exceed
some specified threshold. This work studies the improvement in
TC obtainable with successive interference cancellation (SIC), an
important receiver technique that has been shown to achieve the
capacity of several classes of multiuser channels, but has not been
carefully evaluated in the context of ad hoc wireless networks. This
paper develops closed-form upper bounds and easily computable
lower bounds for the TC of ad hoc networks with SIC receivers,
for both perfect and imperfect SIC. The analysis applies to any
multiuser receiver that cancels the K strongest interfering signals
by a factor : E [0; 1]. In addition to providing the first closed-form
capacity results for SIC in ad hoc networks, design-relevant
insights are made possible. In particular, it is shown that SIC
should be used with direct sequence spread spectrum. Also, any
imperfections in the interference cancellation rapidly degrade its
usefulness. More encouragingly, only a few—often just one—interfering
nodes need to be canceled in order to get the vast majority
of the available performance gain
Multi-hop Relaying with Optimal Decode-and-Forward Transmission Rate and Self-Immunity to Mutual Interference among Wireless Nodes
Abstract-In this paper we show that multi-hop relaying with immunity to mutual interference among relays can be realized in multi-hop ad hoc wireless networks with full-duplex decodeand-forward relays that exploit appropriate packet encoding and successive interference cancellation. This resolves fundamentally the mutual interference challenge involved in multi-hop wireless network research. Based on this interference immune phenomenon, a relay selection algorithm is developed to find the optimal hop count and the optimal relays that maximize sourcedestination decode-and-forward transmission rate. The algorithm constructs the optimal multi-hop paths from a source node to all other network nodes simultaneously with a quadratic complexity O(N 2 ), where N is the network size. This algorithm is efficient for wireless networks with arbitrary size, including extremely large sizes, and can potentially play a fundamental role in exploring multi-hop wireless networks. Surprisingly, this wireless networking algorithm is similar to the well-known Djikstra's algorithm of wired networks. Simulations are conducted to demonstrate the efficiency and the superior performance of the new algorithm
Transmission Capacity of Full-Duplex MIMO Ad-Hoc Network with Limited Self-Interference Cancellation
In this paper, we propose a joint transceiver beamforming design to
simultaneously mitigate self-interference (SI) and partial inter-node
interference for full-duplex multiple-input and multiple-output ad-hoc network,
and then derive the transmission capacity upper bound (TC-UB) for the
corresponding network. Condition on a specified transceiver antenna's
configuration, we allow the SI effect to be cancelled at transmitter side, and
offer an additional degree-of-freedom at receiver side for more inter-node
interference cancellation. In addition, due to the proposed beamforming design
and imperfect SI channel estimation, the conventional method to obtain the
TC-UB is not applicable. This motivates us to exploit the dominating interferer
region plus Newton-Raphson method to iteratively formulate the TC-UB. The
results show that the derived TC-UB is quite close to the actual one especially
when the number of receive-antenna is small. Moreover, our proposed beamforming
design outperforms the existing beamforming strategies, and FD mode works
better than HD mode in low signal-to-noise ratio region.Comment: 7 pages, 4 figures, accepted by Globecom 201
Spectral Efficiency Scaling Laws in Dense Random Wireless Networks with Multiple Receive Antennas
This paper considers large random wireless networks where
transmit-and-receive node pairs communicate within a certain range while
sharing a common spectrum. By modeling the spatial locations of nodes based on
stochastic geometry, analytical expressions for the ergodic spectral efficiency
of a typical node pair are derived as a function of the channel state
information available at a receiver (CSIR) in terms of relevant system
parameters: the density of communication links, the number of receive antennas,
the path loss exponent, and the operating signal-to-noise ratio. One key
finding is that when the receiver only exploits CSIR for the direct link, the
sum of spectral efficiencies linearly improves as the density increases, when
the number of receive antennas increases as a certain super-linear function of
the density. When each receiver exploits CSIR for a set of dominant interfering
links in addition to the direct link, the sum of spectral efficiencies linearly
increases with both the density and the path loss exponent if the number of
antennas is a linear function of the density. This observation demonstrates
that having CSIR for dominant interfering links provides a multiplicative gain
in the scaling law. It is also shown that this linear scaling holds for direct
CSIR when incorporating the effect of the receive antenna correlation, provided
that the rank of the spatial correlation matrix scales super-linearly with the
density. Simulation results back scaling laws derived from stochastic geometry.Comment: Submitte
Performance of Optimum Combining in a Poisson Field of Interferers and Rayleigh Fading Channels
This paper studies the performance of antenna array processing in distributed
multiple access networks without power control. The interference is represented
as a Poisson point process. Desired and interfering signals are subject to both
path-loss fading (with an exponent greater than 2) and to independent Rayleigh
fading. Using these assumptions, we derive the exact closed form expression for
the cumulative distribution function of the output
signal-to-interference-plus-noise ratio when optimum combining is applied. This
results in a pertinent measure of the network performance in terms of the
outage probability, which in turn provides insights into the network capacity
gain that could be achieved with antenna array processing. We present and
discuss examples of applications, as well as some numerical results.Comment: Submitted to IEEE Trans. on Wireless Communication (Jan. 2009
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