Showing papers on "Channel allocation schemes published in 2004"

Methods for implementing a dynamic frequency selection (dfs) and a temporary channel selection feature for wlan devices

Abstract: Various regulatory domains promulgate standards to define how wireless devices should operate in certain frequency bands The 5 GHz spectrum is of particular importance to certain regulatory domains because of radar systems also operating in this spectrum To avoid interference with such radar systems, wireless devices operating in this spectrum should be able to detect radar and quickly vacate any channels currently used by the radar systems In a channel switching technique, if the new channel is radar-exempt, then normal operation commences on the new channel If the new channel is non-radar-exempt, then normal operation commences on a temporary radar-exempt channel and an aggregate background scan can be performed on the new channel If no radars are detected using the aggregate background scan, then operation is switched from the temporary radar-exempt channel to the new channel This channel switching technique minimizes disruption to users during a radar event

Modeling wireless links for transport protocols

Abstract: Wireless links have intrinsic characteristics that affect the performance of transport protocols; these include variable bandwidth, corruption, channel allocation delays, and asymmetry. In this paper we review simulation models for cellular, WLAN and satellite links used in the design of transport protocols, and consider the interplay between wireless links and transport. We argue that the design and evaluation of transport protocols can be improved by providing easily available models of wireless links that strike a balance between realism, generality, and detail.There is an ongoing tussle between wireless link design and transport protocol design, with papers about how wireless link designers should take into account the dynamics of TCP, and other papers about how TCP and other transport protocols can be designed or modified for better performance over current wireless link technologies. In this paper we consider how appropriate models for wireless links can help in this tussle, and in the general design and evaluation of transport protocols over wireless links.

Adaptive fair channel allocation for QoS enhancement in IEEE 802.11 wireless LANs

Abstract: The emerging widespread use of real-time multimedia applications over wireless networks makes the support of quality of service (QoS) a key problem. In this paper, we focus on QoS support mechanisms for IEEE 802.11 wireless ad-hoc networks. First, we review limitations of the upcoming IEEE 802.11e enhanced DCF (EDCF) and other enhanced MAC schemes that have been proposed to support QoS for 802.11 ad-hoc networks. Then, we describe a new scheme called adaptive fair EDCF that extends EDCF, by increasing the contention window during deferring periods when the channel is busy, and by using an adaptive fast backoff mechanism when the channel is idle. Our scheme computes an adaptive backoff threshold for each priority level by taking into account the channel load. The new scheme significantly improves the quality of multimedia applications. Moreover, it increases the overall throughput obtained both in medium and high load cases. Simulution results show that our new scheme outperforms EDCF and other enhanced schemes. Finally, we show that the adaptive fair EDCF scheme achieves a high degree of fairness among applications of the same priority level.

Multibid auctions for bandwidth allocation in communication networks

Abstract: In this paper, we design a bandwidth pricing mechanism that solves congestion problems in communication networks. The scheme is based on second-price auctions, which are known to be incentive compatible when a single indivisible item is to he sold (users have no interest to lie about the price they are willing to pay for the resource) and to lead to an efficient allocation of resources in the sense that it maximizes social welfare. We prove these properties when an infinitely divisible resource (bandwidth on a communication link) is to he shared among users who are allowed to submit several bids when they want to establish a connection. Our scheme is highly related to the progressive second price auction of Lazar and Semret where players bid sequentially until an (optimal) equilibrium is reached. While keeping their incentive compatibility and efficiency properties, our scheme presents the advantage that the multibid is submitted once only, saving a lot of signalization overhead.

Dynamic load balancing and sharing performance of integrated wireless networks

Abstract: The capacity of wireless networks can be increased via dynamic load balancing/sharing by employing overlay networks on top of the existing cellular networks. One such recently proposed system is the integrated cellular and ad hoc relay (iCAR) system, where an overlay ad hoc network is employed to use the resources efficiently by dynamically balancing the load of the hot spots in the cellular network, and to provide quality-of-service to subscribers, no matter where they are located and when the request is made. It is assumed that this overlay network operates in the 2.4-GHz Industrial, Scientific, and Medical (ISM) band and, hence, the number of available ISM-band relay channels used for load balancing will be limited due to other users' interference at a given point in time. In this paper, the impact of ISM-band interference on the performance of iCAR systems, which is a representative hybrid wireless network, is studied, and it is shown that dynamic load balancing and sharing capabilities of iCAR systems are strictly dependent on the availability of the ISM-band relay channels. In addition to quantifying the impact of the number of available relay channels on the performance of iCAR systems, a simple channel assignment scheme to reduce the performance degradation due to other users' interference is also provided. Results show that this interference avoidance technique can improve the realistic performance of iCAR-like hybrid wireless networks by 12%-23% when the interferers are uniformly distributed in the ISM-band.

Channel-adaptive resource allocation for scalable video transmission over 3G wireless network

Abstract: The paper addresses the important issues of resource allocation for scalable video transmission over third generation (3G) wireless networks. By taking the time-varying wireless channel/network condition and scalable video codec characteristic into account, we allocate resources between source and channel coders based on the minimum-distortion or minimum-power consumption criterion. Specifically, we first present how to estimate the time-varying wireless channel/network condition through measurements of throughput and error rate in a 3G wireless network. Then, we propose a new distortion-minimized bit allocation scheme with hybrid unequal error protection (UEP) and delay-constrained automatic repeat request (ARQ), which dynamically adapts to the estimated time-varying network conditions. Furthermore, a novel power-minimized bit allocation scheme with channel-adaptive hybrid UEP and delay-constrained ARQ is proposed for mobile devices. In our proposed distortion/power-minimized bit-allocation scheme, bits are optimally distributed among source coding, forward error correction, and ARQ according to the varying channel/network condition. Simulation and analysis are performed using a progressive fine granularity scalability video codec. The simulation results show that our proposed schemes can significantly improve the reconstructed video quality under the same network conditions.

Power minimization for multi-cell OFDM networks using distributed non-cooperative game approach

Abstract: In this paper, we use a noncooperative game approach to have distributed subchannel assignment, adaptive modulation, and power control for multi-cell OFDM networks. The goal is to minimize the overall transmitted power under each user's maximal power and minimal rate constraints. Our contribution is to model and solve this complicated problem by a distributed noncooperative game approach: Each user water-fills its power to different subchannels regarding other users' powers as interference. A noncooperative game is constructed for each user to compete with others. A method is constructed as a mediator (judge) for the game. From the simulation results, the proposed scheme reduces the overall transmitted power greatly compared with the fixed channel assignment algorithm and pure water-filling algorithm.

Automatic channel allocation for small wireless local area networks using graph colouring algorithm approach

Abstract: Classical graph colouring and its generalisations have been used to model various frequency and channel allocation processes in different radio and wireless network contexts for some time now. However, most of this work has targeted cellular networks and graphs with a relatively large number of nodes. In this article we demonstrate how graph colouring can be used as a theoretical basis for a protocol to effectively assign channels to WLAN access points. We also give the outline of the protocol operation, and show its effectiveness with real-life wireless networks.

A proportional-fair power allocation scheme for fair and efficient multiuser OFDM systems

Abstract: In this paper we investigate adaptive resource allocation schemes in multiuser OFDM systems for fair share of resources and efficient operation. We employ the CDF-based scheduling (CS) algorithm for the subcarrier allocation, taking advantage of its distinctive feature of analyzability and multiuser diversity. Noting that conventional power allocation schemes do not exhibit efficient and fair operations in heterogeneous user channel environments, we present a new algorithm called proportional-fair power allocation (PFPA). This algorithm is designed to allocate transmission power in such a way that the resulting relative throughput-increment is identical for all subcarriers. The PFPA algorithm is shown to be equivalent to the power allocation of the asymptotically optimal algorithm which exhibits the largest achievable region in the asymptotic case. Numerical results reveal that the combined CS-PFPA algorithm improves the overall system capacity in terms of time-average throughput and provides efficient estimation of user performance. Further, the CS-PFPA algorithm can meet each user's requirements using a minimum amount of resources, so it renders an efficient and fair means for resource allocation in multiuser OFDM systems.

Channel assignment in cellular communication using a great deluge hyper-heuristic

Abstract: This paper proposes a methodology for the channel assignment problem in the cellular communication industry. The problem considers the assignment of a limited channel bandwidth to satisfy a growing channel demand without violating electromagnetic interference constraints. The initial solution is generated using a random constructive heuristic. This solution is then improved by using a hyper-heuristic technique based on the great deluge algorithm. Our experimental results, on benchmarks data sets, gives promising results.

Primary channel assignment based MAC (PCAM) - a multi-channel MAC protocol for multi-hop wireless networks

Abstract: Some wireless MAC protocols such as IEEE 802.11 were not designed to capitalize on the available multiple channels in an efficient manner. In this paper, we propose a novel multi-channel medium access control protocol for wireless networks which we term us "primary channel assignment based MAC". The protocol is based on the use of primary channel assignment, which is used by other nodes to find the corresponding node. We also introduce a method to reduce the hidden terminal problem encountered in multi-channel designs by proposing a modified transmission range threshold. The scheme eliminates the need for a separate dedicated control channel or time slot that is usually prone to saturation when the traffic increases. The proposed scheme also addresses the broadcast messages problem in multi-channel design. The scheme is based on IEEE 802.11 DCF protocol. The performance of the proposed protocol is compared to two other multi-channel schemes. In an ad-hoc network, the protocol outperforms the other protocols by up to 140%.

Channel allocation in multi-user MIMO wireless communications systems

Abstract: The use of multi-user multiple input multiple output (MIMO) processing algorithms in wireless communication systems requires new channel allocation algorithms that can intelligently assign users to channels that can best take advantage of the spatial processing available at both transmitter and receiver. The availability of spatial processing at the receiver adds yet another variable to the classic channel allocation problem, making it very difficult to find the optimal solution for a particular set of users at a reasonable computational cost. We propose a two-step heuristic solution. The first step is the computation of a metric that quantifies the spatial compatibility of two users. The second step is to group the users into shared channels based on optimizing the sum of the compatibility metrics over all groups. we also propose a modified version of the algorithm in which the sub-channels (from different multipath components) of a single user are not required to share the same time-domain channel. In simulations, these algorithms come reasonably close to the optimal solution at a moderate computational cost.

Resource allocation for wireless relay channels

Abstract: Resource allocation for a fading orthogonal relay channel model is investigated, where the source transmits to the relay and destination in one channel, and the relay transmits to the destination in an orthogonal channel. Separate power constraints at the source and relay are assumed. The fading state information is assumed to be known at both the transmitter and receiver. The source and relay can allocate their power adaptively according to the instantaneous channel state information. An achievable rate for this model is derived, and is optimized over the power allocation at the source and relay. This optimization is a max-min problem. A general technique for solving this max-min problem is introduced and applied to derive the optimal power allocation. The analysis is extended to the joint optimization of power and channel resource (time and bandwidth) allocations. In these scenarios, the maximum capacity of the channel (optimized over all possible power and channel resource allocations) is obtained for some special cases.

Optimal subchannel allocation scheme in multicell OFDMA systems

Abstract: In this paper, subcarrier allocation schemes for cellular orthogonal frequency division multiple access (OFDMA) systems with adaptive modulation and coding (AMC) is considered. An LP formulation with the constraints of quality-of-service (QoS) and limited bandwidth was made to achieve optimal system throughput. We propose an optimal subcarrier allocation scheme which allows cell coordination to assign subcarrier reuse factor and modulation scheme for each subcarrier. Also, to reduce computational complexity, a simplified cell coordination scheme is suggested. The capacity increase can be achieved by properly selecting modulation scheme and reuse factor of the subcarrier, which is validated by simulations.

Radio resource allocation for cellular networks based on OFDMA with QoS guarantees

Abstract: In this paper we address the problem of radio resource allocation for QoS support in the downlink of a cellular OFDMA system. The major impairments considered are cochannel interference (CCI) and frequency selective fading. The allocation problem involves assignment of base stations and subcarriers, bit loading, and power control, for multiple users. We propose a three-stage, low-complexity, heuristic algorithm to distribute radio resources among multiple users according to their individual QoS requirements, while at the same time maintaining the QoS of already established links in all the cochannel cells. The allocation objective is to minimize the total transmit power, which adds to reducing CCI. Simulation results show a superior performance of the proposed method when compared to classical radio resource management techniques. Our scheme allows us to achieve almost 6 times higher capacity (sum data rate) than the method based on FDMA with power control, at a blocking probability of 0.02.

A call admission and rate control scheme for multimedia support over IEEE 802.11 wireless LANs

Abstract: In this paper, we proposed a novel call admission and rate control (CARC) scheme. Unlike previous research works that are focused on providing service differentiation in the contention-based 802.11 DCF, we aim to support stringent QoS requirements of real-time and streaming traffic. The key idea of this scheme is to regulate the arriving traffic of the WLAN such that the network can work at an optimal point. We first show that the channel busyness ratio is a good indicator of the network status in the sense that it is easy to obtain and can accurately and timely represent channel utilization. Then we propose two algorithms that function upon the use of the channel busyness ratio. The call admission control algorithm is used to regulate the admission of real-time or streaming traffic and the rate control algorithm to control the transmission rate of best effort traffic. A comprehensive simulation study in ns-2 has verified the performance of our proposed CARC scheme, showing that the original 802.11 DCF protocol can statically support strict QoS requirements, such as those required by voice over IP or streaming video, and at the same time, achieve a high channel utilization.

A distributed dynamic channel allocation technique for throughput improvement in a dense WLAN environment

Abstract: In a dense WLAN environment, the signal coverage area of each access point (AP) typically has significant overlap with that of the neighboring APs. This is a problem if there are limited frequency channels. This paper presents an algorithm that can improve per-user throughput significantly, particularly for nonuniform traffic conditions. It is based on a cellular neural network model. Like a cellular neuron changing its state, based on the information of its neighboring neurons, every AP determines the best channel it should use in the next time slot, based solely on the traffic load of its neighboring APs and the channels used by them in the current time slot, but it actually switches to that channel with some fixed probability less than one. All APs in the network perform the above operation simultaneously. Computer simulations show that (1) given any traffic load distribution and any initial channel allocation, the algorithm converges to an equilibrium state in a short time, in which the overall throughput of the network is significantly improved; and (2) there exists an optimal switching probability that can minimize the time for the algorithm to reach the equilibrium state. The proposed technique has significant practical value due to its simplicity and effectiveness.

Performance analysis of the adaptive EXP/PF channel scheduler in an AMC/TDM system

Abstract: The adaptive EXP/PF AU; PL. DEFINE "EXP" ALSO channel scheduler proposed in Rhee et al. (2003) is an enhancement to the proportional fairness (PF) channel scheduler in that it guarantees delay sensitive services having the desired service delay outage probability as well as best-effort services in the forward link of an adaptive modulation and coding when used with time-division multiplexing (AMC/TDM) system. In this letter, assuming that there are many best-effort service users and one streaming service user requiring maximum delay constraints of 3 s, the system throughput of the adaptive EXP/PF scheduler is evaluated for different channel conditions of the streaming service user and is also compared with PF scheduler and its upper bound of throughput. The results show that the adaptive EXP/PF algorithm offers high system throughput as well as fairness among best-effort service users and guarantees streaming services of a desired delay constraint and outage probability.

Channel allocation algorithms for multi-carrier systems

Abstract: This study focuses on orthogonal channel allocation strategies, yielding multiuser diversity with a deterministic channel, for use in an N-user system with N parallel sub-channels. The techniques are applicable, for instance, in orthogonal frequency division multiple-access (OFDMA) systems with dynamic sub-carrier allocation. We show that multiuser diversity, and thus an increase of aggregate data rates with the size of the user population, can still be successfully achieved even under a hard fairness constraint. Furthermore, we provide algorithms which perform channel allocation yielding a variable-rate with constant power and fixed-rate with variable power. We show the effect of system bandwidth (and thus sub-channel correlation) on multiuser diversity. The techniques considered here do not require phase information in the channel allocation process, which, from a practical point-of-view, is particularly important for time-division duplex systems exploiting channel reciprocity.

Exploiting user profiles to support differentiated services in next-generation wireless networks

Abstract: In the next-generation wireless network, user profiles such as the location, the velocity (both speed and direction), and the resource requirements of the mobile device can be accurately determined and maintained by the network on a per-user basis. We investigate the design of a wireless network architecture that exploits user profiles to maximize network efficiency and provide better quality-of-service (QoS) to different classes of users. In this article we provide implementation guidelines of such an architecture for the third-generation partnership project (3GPP) network. The key underlying primitive of the architecture is the use of both real-time and aggregate user profiles to perform advance resource reservation in the handoff target cells of the wireless cellular network. We identify various factors that can influence the efficiency of the resource reservation scheme, and through a simulation analysis of an example scenario we show the impact of these factors on the QoS that profiled users receive. The example scenario comprises two service classes: a high cost, profiled service with higher QoS; and a lower cost, non-profiled service with best-effort QoS. The results show that high QoS can be guaranteed to users who subscribe to the profiled service.

An integrated adaptive bandwidth-management framework for QoS-sensitive multimedia cellular networks

Abstract: Bandwidth is an extremely valuable and scarce resource in a wireless network. Therefore, efficient bandwidth management is necessary in order to provide high-quality service to users in a multimedia wireless/mobile network. In this paper, we propose new online bandwidth-management algorithms for bandwidth reservation, call admission, bandwidth migration, and call-preemption strategies. These techniques are combined in an integrated framework that is able to balance the traffic load among cells accommodating heterogeneous multimedia services while ensuring efficient bandwidth utilization. In addition, our online framework to adaptively control bandwidth is a cell-oriented approach that has low complexity, which makes it practical for real cellular networks. Simulation results indicate the superior performance of our bandwidth-management framework to strike the appropriate performance balance between contradictory quality-of-service requirements.

Handheld routers: intelligent bandwidth aggregation for mobile collaborative communities

Abstract: Multi-homed, mobile wireless computing and communication devices can spontaneously form communities to logically combine and share the bandwidth of each other's wide-area communication links using inverse multiplexing. But membership in such a community can be highly dynamic, as devices and their associated WAN links randomly join and leave the community. We identify the issues and tradeoffs faced in designing a decentralized inverse multiplexing system in this challenging setting, and determine precisely how heterogeneous WAN links should be characterized, and when they should be added to, or deleted from, the shared pool. We then propose methods of choosing the appropriate channels on which to assign newly-arriving application flows. Using video traffic as a motivating example, we demonstrate how significant performance gains can be realized by adapting allocation of the shared WAN channels to specific application requirements. Our simulation and experimentation results show that collaborative bandwidth aggregation systems are, indeed, a practical and compelling means of achieving high-speed Internet access for groups of wireless computing devices beyond the reach of public or private access points.

HARMONICA: enhanced QoS support with admission control for IEEE 802.11 contention-based access

Abstract: Currently deployed IEEE 802.11 WLANs work mostly with distributed coordination function (DCF) mode at the MAC layer, which does not provide QoS support. The upcoming IEEE standard 802.11e achieves service differentiation by assigning different channel access parameters (CAPs) to different traffic classes at the MAC layer. However, such relative differentiation does not yield QoS guarantee. In practice, appropriately selecting CAPs a priori is difficult. Time-varying traffic loads also make the use of fixed CAPs inefficient for both QoS support and channel utilization. We propose a novel architecture called HARMONICA, in which the access point dynamically selects the best CAPs for each traffic class to optimally match their QoS requirements. We present and discuss a simple admission control mechanism used by HARMONICA to avoid congestion. Our simulation results demonstrate that under an interference-free environment, HARMONICA can guarantee the QoS for all traffic classes while simultaneously achieving quasi-optimal channel utilization.

Bandwidth-reservation scheme based on road information for next-generation cellular networks

Abstract: Channel-reservation techniques have been widely studied in cellular networks in order to meet the desired quality-of-service requirements. In this paper, a distributed predictive channel-reservation scheme, called the road-map-based channel-reservation scheme (RMCR), and a call-admission-control algorithm are proposed. The goal is to reduce the handoff-dropping probability and to improve the bandwidth utilization. In the RMCR scheme, we assume that base stations (BSs) are equipped with road-map information and that mobile stations (MSs) are equipped with global positioning systems (GPS) devices. MSs periodically report their GPS location information to their BSs. Based on the location information of the MSs at two consecutive epochs, the BSs estimate the speed and moving direction of the MSs. Furthermore, the BSs estimate the probability that the MSs will enter the neighboring cells based on their velocity and the road-map information stored in the BSs. The BSs then compute the amount of bandwidth to be reserved, based on such estimation. With the road-map information, the BSs can make a more-accurate prediction on the user's mobility and, hence, reduce unnecessary bandwidth reservation. Simulation results show that RMCR is capable of keeping the handoff-dropping probability low and allocating bandwidth to new/handoff calls efficiently. We also show that RMCR is robust with respect to system parameters such as user's speed, the density of roads, the accuracy of mobility measurement, and so on.

Cyclostationarity-based methods for the extraction of the channel allocation information in a spectrum pooling system

Abstract: Spectrum pooling can be considered as a first step towards a fully dynamic spectrum allocation strategy. It allows a license owner to share a sporadically used part of his licensed spectrum with a renter system, until he needs it himself. For the smooth operation of a spectrum pooling scheme, the renter system has to monitor the channel and extract the channel allocation information (CAI), i.e. it has to detect which parts of the shared spectrum the owner system accesses, in order to immediately vacate the frequency bands being required by the license owner and to gain access to the frequency bands which the license owner has stopped using. This work presents and compares two methods based on exploiting the cyclostationary properties of the spectrum owner signal for the extraction of the CAI in a specific spectrum pooling scenario, where the license owner is a GSM network and the spectrum renter is an OFDM based WLAN system.

Automatic optimization algorithms for the planning of wireless local area networks

Abstract: The planning of WLAN infrastructures that supply large buildings or areas requires the consideration of many aspects and therefore is a difficult task if done manually. In this paper, a method is presented that allows one to optimize such networks automatically. The approach is based on predictions of the received power to account for the propagation conditions that have a major impact on the performance of WLANs. The optimization is applied to a set of possible locations where access points can be installed. Out of this set, a minimum selection of locations is made to meet the given requirements. These consist of the determination of areas with different priorities and the definition of further parameters. It not only takes into account the required coverage and capacity but also the interference situation. The arising co-channel interference is minimized by an appropriate assignment of the available carrier frequencies. The discussed approach may not find the global optimum in all cases, but it yields a suggestive result based on the locations defined by the network planner. Due to the very short computation time, different configurations can be analyzed very quickly.

Radio resource management in wireless LANs

Abstract: Some chief information officers and information technology managers are reluctant to deploy wireless LANs. Among their concerns are reliability, availability, performance, and deployment. Each of these concerns can be directly addressed through the radio resource management techniques used in a new generation of wireless LAN equipment. The new capabilities include dynamic channel assignment, dynamic power control, and load sharing. Changing from the relatively static radio resource management techniques generally in use today to dynamic methods like those highlighted in this article helps to increase the capacity and improve the performance of large-scale wireless LANs.

The marginal user principle for resource allocation in wireless networks

Abstract: We consider the problem of resource allocation in a wireless network operated by a single service provider. The motivating model is the downlink in a cellular network where the provider sets the price of entry into the wireless network and then allocates power levels (and transmission rates) to the participating users as a function of the users' channel conditions according to a pre-specified policy. The provider's goal is to design the power allocation policy that maximizes its revenue, recognizing the effects of his decisions on the choice of users to join the network. We show that the power allocation policy chosen by the service provider satisfies the following marginal user principle: the network allocates power levels such that the utility of the marginal user, who is indifferent to joining the network or not, is maximized. While the motivation is drawn from power allocation, the marginal user principle also generalizes to other resource allocation problems.

Opportunistic dynamic subchannel allocation in multiuser OFDM networks with limited feedback

Abstract: In this paper we present a simple scheme for subchannel allocation in OFDM multiuser networks in the presence of limited feedback, in particular, when only one bit of information per subchannel is available at the base station. Our objective is to maximize the sum rate capacity of the network in the downlink transmission. We show that even with very limited feedback the sum rate capacity growth is the same as the fully informed transmission. We also extend this result to the case when subchannels are correlated.

Multiterabit/s DWDM terrestrial transmission with bandwidth-limiting optical filtering

Abstract: Wavelength-division multiplexing (WDM) systems based on 40-Gb/s channel bit rate appear as likely successors of current widespread N/spl times/10 Gb/s systems. However, they will provide larger throughputs than N/spl times/10 Gb/s systems only if some specific techniques are implemented, so as to improve the utilization ratio of the optical bandwidth, namely, the information spectral density (ISD). Narrow optical filtering is one such technique. Based on a review of some of our multiterabit/second transmission experiments in terrestrial configurations, we highlight the benefits of optical filtering to reshape the channel spectra. First, we show that vestigial sideband (VSB) narrow filtering of nonreturn-to-zero (NRZ) data makes 0.64-bit/s/Hz ISD possible over long-haul and ultra-long distances, provided that a specific wavelength allocation scheme is implemented. Using this scheme, a record 10-Tb/s capacity is demonstrated over 300 km by applying different data along each of the two polarization axes. However, along a single polarization axis and when channels are packed closer with NRZ-VSB filtering, at 0.8-bit/s/Hz ISD, nonlinear interactions between channels affect system performance and reduce the maximum error-free distance. We show that these interactions can be contained, still using narrow optical filtering, but by resorting to an alternative modulation format, namely, phase-shaped binary transmission.