Wireless Local Area Network Nodes Research Articles

IPv6 based relay gateway protocol in hybrid networks

During the past few years, WMAN (Wireless Metropolitan Area Network) and WLAN (Wireless Local Area Network) provided fast, convenient and reliable solution for all kinds of users. With the development of the communication technology, the future wireless networks will allow mobile users access Internet anywhere, anytime. Therefore, it is a natural trend to combine different wireless networks to provide a seamless roaming for users. It is feasible for mobile terminal which have multiple modes to handoff between different networks. A relay gateway protocol for the WLAN-mode nodes (mono-mode WLAN nodes and dual-mode nodes) in the hybrid network of IEEE 802.16 WMANs and IEEE 802.11 WLANs is proposed to provide wider mobility. Dual-mode mobile nodes with good service can provide WLAN links to nearby WLAN-mode nodes with bad service or out of the WLAN coverage. Simulation results show that the relay gateway scheme can improve network performance of the hybrid networks. Moreover, the relay gateway method can bring additional service coverage and increase the capacity of WMANs and WLANs.

Qualnet Simulation of Channel Collision between IEEE 802.15.4 and IEEE 802.11b for Various Topologies

Coexistent heterogeneous wireless networks may interfere with each other and result in significant performance degradation when devices are collocated in the same environment. With the increasingly deployed Wireless Personal Area Network (WPAN) and Wireless Local Area Network (WLAN) devices, channel conflict has become very frequent and severe when one WPAN technology coexists with other WLAN technologies in the same interfering range. In this paper, we study the coexistence issue between IEEE 802.15.4 and IEEE 802.11b. We present analytical models on the non-conflicting channel allocation probabilities, focusing on the coexistence scenarios of IEEE 802.15.4 coexisting with IEEE 802.11b. The interference model of IEEE 802.15.4 wireless Personal area network (WPAN) affected by IEEE 802.11b wireless Local area network (WPAN) also presented. The packet error rate (PER) of the IEEE 802.15.4 under the interference of the IEEE 802.11b is analyzed, and is obtained by the bit error rate (BER) and the collision time. The BER is obtained from signal to noise and interference ratio. The safe distance ratio can be obtained from the PER. The analytic results are validated for various topologies using Qualnet 4.5 simulation. Further this paper investigates the PER of IEEE 802.15.4, with the consideration of the mobility models of the WLAN nodes. Simulation results are analyzed for the mobility model with varying speed.

Hidden Node Problem Aware Routing Metrics for WLAN Mesh Networks

This paper proposes two novel hidden node problem aware routing metrics for wireless local area network (WLAN) mesh networks. To select the path that is least affected by the serious hidden node problem, we propose two routing metrics, MNn and MPCP, that take into account the number of neighboring nodes (Nn) and the packet collision probability (PCP), respectively. The PCP is estimated from neighbor information that is periodically gathered as state announcement packets, which include the transmission time ratio and the neighbor list. Simulation results show that the first proposed MNn routing metric tends to be less effective as the number of WLAN nodes increases, i. e., the mesh network becomes denser. On the other hand, with an acceptable increased in the control overhead in the mesh network due to the neighbor information, the second proposed MPCP routing metric improves the number of allowable concurrent voice over Internet Protocol (VoIP) calls and the user datagram protocol (UDP) data throughput compared to the MNn metric. The MPCP also provides better performance than the other conventional routing metrics, the hop count, and the Airtime proposed in IEEE 802.11s.