Wavelength routed optical networks can experience increased call blocking due to insufficient quality of transmission. The routing and wavelength assignment algorithm must verify the quality of the lightpath before accepting it. In this paper, analytical expressions for the total blocking probability are derived for first fit wavelength assignment for networks suffering from transmission impairments. Physical layer degradations considered include amplifier noise and crosstalk between WDM channels. The technique effectively predicts the performance for wavelength selection techniques that consider a single candidate channel or all channels for quality of transmission compliance. The analysis is also applicable to first-fit algorithms with different static channel orderings.

As an optical signal propagates along a lightpath to its destination in wavelength-routed optical networks (WRONs), the quality of transmission (QoT) is degraded by transmission impairments such as crosstalk and amplified spontaneous emission noise. Consequently, the signal’s bit error rate at the destination’s receiver can become unacceptably high. Recently, many BER-aware connection provisioning algorithms have been proposed that incorporate physical layer impairments in terms of increased blocking rate from the BER constraint. However, they have a high computational complexity compared to traditional connection provisioning schemes because of the complexity of BER estimation. The delay involved in the computation greatly affects the performance in distributed networks because the latency worsens the contention and makes instantaneous network status impossible to obtain. In this paper, distributed connection provisioning schemes are compared using two BER estimation procedures and several wavelength assignment algorithms. Simulation results show the effects of delay in connection provisioning and measure the performance in terms of blocking probability.

In this paper, we consider the problem of routing and wavelength assignment (RWA) in all-optical networks, where signals propagate in the optical domain (with no electrical regeneration) from end-to-end. In such networks, physical impairments are an issue and can cause calls to be blocked if a minimum quality of transmission (QoT) measured in terms of bit-error rate (BER) cannot be guaranteed for all calls, at all times. We focus on the routing component of RWA to incorporate QoT: we propose a novel RWA algorithm that finds a route based on both the network utilization and the physical impairments experienced over the tentative route. Our algorithm is fully decentralized and is shown using simulations to perform better than previously proposed algorithms on a regional-sized network.

Crosstalk originating from optical switching devices and demultiplexers can be the dominant physical impairment in large all-optical networks. When a centralized network controller must estimate the impact of crosstalk and other physical impairments on the quality of a lightpath, this can add significant latency. In this paper, QoS-aware wavelength assignment algorithms are proposed that consider both bit error rate and latency guarantees. A technique called wavelength ordering is presented to alleviate physical impairments and also decrease the processing delay due to bit-error-rate (BER) estimation. Simulations presented show that the wavelength ordering algorithm outperforms other wavelength assignments when both BER and response latency guarantees are enforced.

As an optical signal propagates along a lightpath to its destination in distributed wavelength-routed optical networks, the signal's quality is degraded by transmission impairments, such as node crosstalk, which is induced by power leaking in the network nodes. Consequently, the bit error rate of the received signal at the destination can be unacceptably high. In this paper, a new adaptive wavelength assignment scheme based on wavelength spectrum separation technique is proposed to combat physical impairments in distributed optical networks. The proposed algorithm outperforms traditional techniques as measured by the blocking probability, adding little complexity.

As an optical signal propagates along a lightpath to its destination in wavelength-routed optical networks (WRONs), the quality of service (QoS) will be degraded by transmission impairments such as crosstalk, which is induced by signals traversing the same optical crossconnects, demultiplexers, and fiber segments. Consequently, the signal's bit error rate at the destination's receiver might become unacceptably high. Recently, many QoS-aware wavelength assignments (WAs) have been proposed that corporate physical layer blocking; these have a high computational complexity compared to traditional WAs because of QoS estimation. In this paper, a new dynamic WA scheme using a wavelength spectrum separation technique is proposed to combat crosstalk occurring in WRONs. Our simulation results show that the new WA scheme has much lower complexity than QoS-aware WA schemes yet has a performance close to the QoS-aware WA schemes.