waashk/dblp huggingface dataset:
network coding for bit error recovery in ieee 802.11 mesh networks. opportunistic routing (or) relies on links of intermediate quality, i.e. packet losses are common. however, the reasons for packet losses are manifold, e.g. a received packet may contain corrupted bits. according to traditional approaches, the receiver discards the whole frame in such a case. in this paper, we present measurements from an indoor ieee 802.11 wireless mesh network (wmn), which indicate that corrupted frames still contain a significant amount of correct data, which can be utilized. in particular, corrupted frames are common for intermediate quality links. bit errors tend to occur in proximity, i.e. they are bursty. furthermore, bit errors are uncorrelated across different receivers in most cases. based on our observations, we propose a harq scheme for or called hybrid arq with limited fragmentation (half). it operates on a hop-by-hop manner and requires only local knowledge. due to the bursty nature of bit errors, we are dividing frames into fragments with additional error detection. using random linear network codes, the sender transmits incremental redundancy until one of its receivers is able to decode all fragments and therefore sends an acknowledgement packet. however, the partial information at all other receivers is not lost. instead, to increase the throughput further, it is also used in subsequent forwarding rounds along the multi-hop route. we implemented a prototype of our protocol to evaluate its performance. with the help of detailed simulations, we analyzed the reasons why half significantly outperforms traditional approaches like dsr.
utility maximization in the multi-user miso downlink with linear precoding. the maximization of an increasing function over the set of achievable rates in a multi-user, multi-antenna downlink is addressed. in general, the set of rates achievable by linear precoding and treating interference as noise is nonconvex. as a result, the corresponding utility maximization problem is nonconvex. the rate region can be convexified by time sharing, and the utility maximization over the convexified region can be solved via lagrange duality. still, subproblems in the dual problem remain nonconvex. it is shown how all the aforementioned nonconvex problems can be solved to global optimality in the framework of monotonic optimization. moreover, it is investigated to what extent utility is increased by time sharing. while all problems can be solved to global optimality, the resulting computational complexity is rather high, thus the proposed solution strategies mainly provide a benchmark for locally optimum, less complex methods. numerical results demonstrate that a method which finds stationary points on the boundary of the rate region can provide close-to-optimum performance.
energy efficient routing in ad hoc networks with nakagami-m fading channels. this paper considers minimum-energy routing problem in poisson random ad-hoc networks with nakagami-m fading channels. we first formulate an analytical model for the transmission power, subject to a certain packet reception probability, under the assumption that the users employ proper power control and slotted aloha protocol. based on this, we consider five routing strategies and compare their energy performances. our results show that, long-hop routing in nakagami-m networks can be more energy efficient than short-hop routing in certain scenarios, especially under light traffic and significant channel fading. when the interference can not be neglected, short-hop routing is typically better. it is also observed that when the path loss exponent is small, intelligent mac mechanisms are critical for the energy efficiencies of routing strategies.
application of analytic wavelet transform for signal detection in nyquist folding analog-to-information receiver. one of the challenges in cognitive radio (cr) is efficiently monitoring a wideband radio frequency (rf) spectrum in order to identify unoccupied bands. compressive sensing (cs) has recently been proposed to address this problem. typical cs techniques, however, involve random projections followed by a computationally intensive signal reconstruction process. since spectral monitoring does require full signal reconstruction - only identification of occupied regions to avoid - we propose a novel spectrum monitoring approach based on the nyquist folding receiver (nyfr) in conjunction with the analytic wavelet transform. the nyfr performs analog compression via a non-uniform sampling process that induces a chirp-like modulation on each received signal. this induced modulation can be measured using time-frequency analysis techniques to determine the original rf band of origin without full signal reconstruction. this paper investigates the feasibility of using the analytic wavelet transform to perform nyfr information recovery in support of cr wideband spectrum sensing.
subcarrier sensing for distributed ofdma in powerline communication. powerline communication (plc) is a preferred choice for smart home network. in this paper, a new system structure is proposed for plc, which is based on distributed orthogonal frequency division multiple access (dofdma). sub-carrier sensing, i.e., sensing every ofdm subcarrier to see if it is occupied or not, is proposed to replace the conventional carrier sensing multiple access (csma) for multi-user contention of a channel. this structure, borrowed from cognitive radio, allows multiple users to opportunistically share the same channel on different subcarriers and therefore increases the channel capacity. two subcarrier sensing methods are proposed: one is based on information theory and the other is based on successive energy comparison. simulations are provided to verify the methods.
density-varying high-end sensor placement in heterogeneous wireless sensor networks. to achieve better performance, we adopt a heterogeneous sensor network (hsn) model. in many applications, the locations of some sensor nodes are controllable. in this paper, first we propose a novel density-varying deployment scheme for high-end sensors (h-sensors) in an hsn. the scheme solves the bottleneck problem in typical many-to-one sensor networks. we then study the optimal placement of h-sensors whose locations are controllable. the goal is to use the minimum number of h-sensors for ensuring successful data delivery, coverage and connectivity in a network for a given lifetime. we present an effective h-sensor placement scheme that can simultaneously achieve coverage, connectivity and data relay requirements while uses a small number of h-sensors. both theoretical proofs and simulation results demonstrate that the proposed h-sensor placement scheme achieves very good performance.
adaptive bitrate and resource allocation for relay-assisted arq transmissions. automatic repeat request (arq) protocols deal with the situations where the selected data rate is not supported by the current channel realization. the inappropriate selection is motivated by the limited channel state information at the transmitter (csit). this work looks into how the arq protocols are applied to the half-duplex relay-assisted transmission with decode-and-forward relays by exploiting the ack feedback channel of the terminals. two implementations are tackled: 1) only the source or 2) source and relay manage the retransmissions under the pure-arq protocol. this work presents an analytical framework for the comparison of both options. the study allows the optimization of the bitrate and amount of resource allocated for the relay transmission phases.
routing to a mobile data collector on a predefined trajectory. in this paper, we propose a distributed scheme for data gathering using a mobile data collector in wireless sensor networks (wsns). in our scheme, a mobile data collector moves along a predefined track over the sensing field and data are forwarded to nodes whose transmission disks overlap with the trajectory of the data collector; these nodes are called relaying nodes. data are classified into two categories: delay-sensitive data and delay-tolerant data. while delay-sensitive data are sent to the data collector directly, delay-tolerant data may be sent to a nearby relaying node, where they wait for the data collector to come and pick them up. we give a theoretical analysis to quantify the impact of data collector mobility on the lifetime of the network as compared to a wsn with a stationary data collector. moreover, we use simulations to evaluate our scheme in practice. simulation results show that our scheme has the potential to prolong the lifetime of the network significantly.
a study of the percolation threshold for k-collaborative wireless networks. how to efficiently use the air interface is a crucial issue in wireless networks. in order to improve the performance, mechanisms have been proposed to improve the reach and the connectivity of nodes in a wireless network. one such mechanism is to use joint, synchronized transmission from a cluster of several nodes to reach nodes outside of the transmission range of any of the transmitting nodes in the cluster. we adopt a simplified model of collaboration where the power at the receiver is the sum of the transmitted power at the sender, and study the performance of such system with clusters of arbitrary size k. we compute theoretical bounds on the gain achieved using collaboration as a function of the cluster size. our key result is to show that, in a percolation framework, the critical node density for the infinite connectedness of the network is significantly reduced by the use of k-cooperation: for large k, it is reduced by a factor which we show to converge towards α√ξ(α)2, where ξ(.) is the riemann zeta function. the previously known best bound on the gain of cooperation was 5/4 = 1.25 for α = 2 and pairwise cooperation, while our results yield a provable gain of at least π2/6 = 1.64. we provide some simulations to display the gain of cooperation in a finite size network as well.
probabilistic data detection for probe-based storage channels in the presence of jitter. probe-storage devices employ large arrays of probes to write/read data in parallel in some storage medium. because of their inherent parallelism and the independence of data retrieved from different probes, these devices lend themselves naturally to low-density parity-check (ldpc) codes and associated soft/iterative decoding techniques. in this paper, a concatenated coding scheme for a particular probe-storage channel is presented that comprises an inner (d, k)-constrained code and an outer ldpc code, and the problem of probabilistic data retrieval for this channel is addressed. in particular, soft information is generated by explicitly accounting for the channel output statistics in the presence of jitter and additive noise, based on derived analytical expressions.
a combined approach for receiver-based mac and network layers in wireless sensor networks. data communication represents the greatest energy cost of wireless sensor networks. both mac and network layers of the protocol stack are responsible for data communication in these networks. this work proposes the receiverbased medium access control (rb-mac) protocol to be used in a combined solution with a receiver-based routing scheme. the main advantage of combining receiver-based mac and routing protocols is that this solution does not use neighbor tables and, consequently, it saves energy when compared with mac and routing protocols that use these tables. simulation results reveal that receiver-based data communication has a great data delivery ratio, and reduces energy consumption, number of transmissions, and collisions wben compared with a senderbased data communication. moreover, we use a model checking techdique to perform the formal verification of rb-mac.
theoretical analysis of selective relaying, cooperative multi-hop networks with fairness constraints. we consider the problem of selective relaying in multi-hop networks. at each slot, a relay and a node along the optimal non-cooperative path are opportunistically selected to transmit to the next-hop node in a cooperative manner. being a promising scheme for fair resource allocation, the proportional fair scheduling (pfs) algorithm provides excellent balance between throughput and fairness via multi-user diversity and game-theoretic equilibrium. to maximize the overall utility along a cooperative multi-hop path, we apply the proportional fair (pf) criterion in selecting nodes and relays for cooperative transmission. furthermore, we analyze and provide an analytical expression for end-to-end throughput of an opportunistic relaying, cooperative multi-hop path with proportional fairness constraints over a rayleigh flat-fading channel. to our knowledge, it is the first time that a closed-form expression is obtained for the throughput of a proportional fair relaying, cooperative multi-hop path. this research is an extension of previous theoretical work on pf for cellular networks.
a novel power allocation scheme for distributed space-time coding. this paper derives an optimal power allocation (pa) to maximize the effective average signal-to-noise ratio (snr) of distributed space-time coding (dstc) in wireless relay networks, where the locations of the relays can be anywhere between the source and destination. it is first shown that in maximizing the average snr, not all the relays might be active, and hence the code performance might be compromised. the amount of fading is then introduced for the relay networks and used as a constraint to derive a novel pa scheme. this new pa is shown to obtain the maximum diversity order of both noncoherent and coherent dstc systems at high snr.
improved topology control method for maximizing traffic delivery ratio in wireless mesh networks with directional antennas. in this paper we proposed a topology control algorithm for the single channel wireless mesh network with m directional antennas equipped on each node. the objective of our algorithm is to maximize the traffic delivery ratio from each nongateway node to gateway nodes, by adjusting the orientations of the directional antennas appropriately. by allowing each antenna connecting to multiple nodes, our proposed algorithm improves traffic delivery ratio by 40%-280%, compared to previous work.
distributed uplink signal processing of cooperating base stations based on iq sample exchange. cellular systems in general suffer from co-channel interference, when simultaneous transmissions in other cells use the same physical resources. in order to mitigate such co-channel interference cooperating base stations (bss) can perform joint multi-antenna signal processing across cell borders. this paper describes a concept of distributed cooperation, where bss communicate directly via a bs-bs interface without central control. a serving bs can serve its terminals on its own or it can request cooperation from one or more supporting bss. by collecting iq samples from the supporting bss' antenna elements, the serving bs can virtually increase its number of receive antennas. exchanging additional parameters allows applying advanced receiver algorithms, e.g., interference rejection or cancelation. performance evaluations by means of simulation show the capability of bs cooperation applied to 3gpp lte in terms of cell and user throughput but it also shows the trade-off in terms of increased backhaul requirement due to bs-bs communication.
support for dynamic adaptation in next generation packet processing systems. designs of next-generation internet architectures propose a diverse and changing set of features in the data path of routers. these routers require high-performance programmable packet processing platforms to allow for dynamic feature deployment and adaptation. in this paper, we present programming abstractions that quantifies processing and storage of network services. we further devise a runtime environment that provides the ability of adaptation to dynamically deployed network services and varying network traffic.
distributed turbo trellis coded modulation for cooperative communications. in this contribution, we propose a distributed turbo trellis coded modulation (dttcm) scheme for cooperative communications. the dttcm scheme is designed based on its decoding convergence with the aid of non-binary extrinsic information transfer (exit) charts. the source node transmits ttcm symbols to both the relay and the destination nodes during the first transmission period. the relay performs ttcm decoding and re-encodes the information bits using a recursive systematic convolutional (rsc) code regardless whether the relay can decode correctly or not. only the parity bits are transmitted from the relay node to the destination node during the second transmission period. the resultant symbols transmitted from the source and relay nodes can be viewed as the coded symbols of a three-component parallel-concatenated ttcm scheme. at the destination node, a novel three-component ttcm decoding is performed. it is shown that the performance of the dttcm matches exactly the exit chart analysis. it also performs very closely to its idealised counterpart that assumes perfect decoding at the relay.
context-aware receiver-driven retransmission control in wireless local area networks. automatic repeat request (arq) techniques employed by leading wireless technologies aim at compensating the high error rates due to radio impairments, but do not offer any differentiated levels of protection. in this work, we propose to enable per-packet differentiation of link layer arq protection (in terms of no. of retransmissions) driven by requirements of the end applications as well as of communication protocols implemented on the mobile terminal. experimental results demonstrate the potential benefits deriving from the proposed strategy, both on tcp data flows and mpeg-4 video streams.
resource criticality analysis of static resource allocations in wdm networks. various static resource allocation algorithms have been used in wdm networks to allocate resources such as wavelength channels, transmitters, receivers, and wavelength converters to a given set of static lightpath demands, based on certain design objectives. however, although optimized resource allocations can be obtained, it remains an open issue how to determine which resources are bottlenecks to achieve better performance. existing static resource allocation algorithms do not explicitly measure the impact of a given resource on the design objective. in this paper, we propose such a measurement based on the lagrangian relaxation (lr) framework. we use the optimized values of lagrange multipliers as a direct measurement of the criticality of resources. such a quantitative measurement can be naturally acquired along with the optimization process to obtain the optimal solution (or a near optimal solution) to the static routing and wavelength assignment (rwa) problem. such a measurement helps to identify critical resources, and thus to decide the best way to add or reallocate resources.
voice service support over cognitive radio networks. in this paper, quality of service (qos) provisioning for voice service over cognitive radio networks is considered. as voice traffic is sensitive to delay, the presence of primary users and the requirement that secondary users should not interfere with them pose many challenges for qos support for secondary voice users. two cognitive medium access schemes are proposed in this paper for the secondary voice users to access the available channel. an analytical model is developed to obtain the voice service capacity (i.e., the maximum number of voice users that can be supported with qos guarantee) for the secondary users, taking the impact of primary users' activities into consideration. the analytical model is validated by the simulation. the analytical results will be useful to support voice service in cognitive radio networks.
pcn-based flow termination with multiple bottleneck links. pre-congestion notification (pcn) is a new packet marking scheme based on which simple measurement-based admission control (ac) and flow termination (ft) are implemented. ft is useful for traffic management in unexpected events, e.g., when admitted flows lead to overload on a link after rerouting which may be due to a link or node failure. while ac is a classic flow control function, ft is new and only little understood so far. the limited literature on ft focuses mainly on a single overloaded link. however, when a link or node fails, redirected traffic is likely to cause overload on multiple backup links (bottlenecks) at the same time. as the packet marking probability for flows traversing multiple bottlenecks is larger than for flows traversing only the most severe bottleneck, more traffic is possibly terminated than needed, i.e. overtermination occurs. this paper quantifies potential overtermination in case of multiple bottlenecks for different ft mechanisms which are currently discussed by the ietf.
downlink ofdma resource allocation under partial channel state information. the problem of resource allocation (ra) in a down-link ofdma system is examined under the realistic assumption of imperfect channel state information (csi) at the base station. in this case, there is a nonzero outage probability that the assigned rate at a particular subcarrier/user pair will not be supported by the true channel realization, which may lead to a significant waste of the system's available resources. it is therefore necessary to obtain ra algorithms that take into account the effect of imperfect csi. by exploiting the statistical description of the imperfect csi, various algorithms are proposed that tradeoff complexity versus performance, aiming at maximizing the system's successfully transmitted rate.
maximizing throughput with multiple power levels in a random access infrastructure-less radio system. we propose and analyse a new random access protocol with multiple power levels selection schemes for infrastructureless wireless networks. in these networks, mobile nodes may communicate with each other without a central entity (base station), where each mobile node will be either in a transmitting mode or in a receiving mode or in an idle mode. throughput with random power levels selection scheme is derived in terms of the transmission probability of each mobile node, receiving probability of each mobile node and the number of power levels. throughput with optimum power levels selection scheme is also derived and compared with the previous one. results show that the optimum transmission probability of each mobile node to achieve the maximum throughput depends only on the number of power levels. the maximum throughput region is devised in terms of transmission probability of each mobile node and the number of power levels. the proposed new random access protocol is truly distributive in nature and can be easily implemented in infrastructure-less wireless access systems without requiring any centralized control.
connectivity optimization for wireless sensor networks applied to forest monitoring. device deployment plays a key role in the performance of any large-scale wireless sensor network (wsn) application. wsn device deployment (i.e. the numbers and positions of the devices) must consider several design factors, viz. coverage, connectivity, lifetime, etc. however, connectivity remains the most fundamental factor especially in a large scale harsh environment. in this paper, we explore the problem of relay node (rn) placement in 3d forestry space. we formulate a generalized rn deployment optimization problem aimed at maximizing the network connectivity with constraints on rns count. we investigate how the number of rns can affect the connectivity of a wsn in a harsh environment. based on quantitative analysis of such effects, the paper sets a threshold on the minimum number of required rns.