Kai-ming Liu

Pricing in combinatorial double auction-based grid allocation model

Abstract This article proposes a novel grid resource allocation model, in which the users and the grid service providers participate in the combinatorial double auction for the resource allocation. To obtain the detailed resource allocation status and the price information, a novel pricing algorithm is designed for the allocation model. Simulation results demonstrate that the proposed algorithm completes the resource allocation and pricing efficiently, and exhibits incentive compatible characteristic. Moreover, users with the higher average price and providers with the lower average price get compensation during the pricing process.

Resource scheduling in downlink LTE-advanced system with carrier aggregation

Abstract In this paper, we focus on the resource scheduling in the downlink of long term evolution advanced (LTE-A) assuming equal power allocation among subcarriers. Considering the backward compatibility, the LTE-A system serves LTE-A and long term evolution (LTE) users together with carrier aggregation (CA) technology. When CA is applied, a well-designed resource scheduling scheme is essential to the LTE-A system. Joint scheduling (JS) and independent scheduling (INS) are two resource scheduling schemes. JS is optimal in performance but with high complexity. Whereas INS is applied, the LTE users will acquire few resources because they can not support CA technology. And the system fairness is disappointing. In order to improve the system fairness without bringing high complexity to the system, an improved proportional fair (PF) scheduling algorithm base on INS is proposed. In this algorithm, we design a weigh factor which is related with the number of the carriers and the percentage of LTE users. Simulation result shows that the proposed algorithm can effectively enhance the throughput of LTE users and improve the system fairness.

An adaptive algorithm for connecting mobile ad hoc network to Internet with unidirectional links supported

Abstract The performance of Internet connectivity is degraded dramatically by blind rebroadcast of gateway discovery packets when obvious unidirectional links are ignored. To overcome this problem, an effective adaptive gateway discovery algorithm for connecting mobile ad hoc network to Internet with unidirectional links supported is proposed in this paper. On the basis of modification for ad hoc on-demand distance vector (AODV), through rebroadcasting the gateway discovery messages and gateway advertisement messages, both of which are extended with local connection information, unidirectional links are successfully removed from global route computations and Internet connectivity is simultaneously enhanced. Furthermore, an adaptive Internet working scheme is adopted to provide the best coverage of gateway advertisement according to dynamically adjusting broadcast range and sending interval of gateway advertisement messages in terms of network conditions. Simulation results show that the proposed hybrid Internet connectivity algorithm can provide better connectivity performance due to avoiding unidirectional links effectively with reasonable overhead.

Distributed channel assignment combined with routing over multi-radio multi-channel wireless mesh networks

Abstract In order to realize the reduction of equipment cost and the demand of higher capacity, wireless mesh network (WMN) router devices usually have several interfaces and work on multi-channels. Jointing channel allocation, interface assignment and routing can efficiently improve the network capacity. This paper presents an efficient channel assignment scheme combined with the multi-radio link quality source routing (MR-LQSR) protocol, which is called channel assignment with MR-LQSR (CA-LQSR). In this scheme, a physical interference model is established: calculated transmission time (CTT) is proposed as the metric of channel assignment, which can reflect the real network environment and channel interference best, and enhanced weighted cumulative expected transmission time (EWCETT) is proposed as the routing metric, which preserves load balancing and bandwidth of links. Meantime, the expression of EWCETT contains the value of CTT, thus the total cost time of channel assignment and routing can be reduced. Simulation results show that our method has advantage of higher throughput, lower end-to-end time delay, and less network cost over some other existing methods.

Capacity analysis of based-regular-topologies cognitive wireless mesh networks with power control

Abstract Capacity analysis is a fundamental and essential work for evaluating the performance of cognitive wireless mesh network (CWMN) which is considered a promising option for the future network. Power control is an efficient way to avoid interference and improve capacity of wireless mesh networks. In this paper, a quantitative result of the per-node average throughput capacity of CWMN with power control is deduced for the first time, which is much helpful for understanding the limitations of CWMN. Firstly, under the large-scale channel fading model and protocol interference model, a closed-form expression for the maximum channel capacity of each node with power control is presented, under the constraint that the interference tolerated by the primary users (PUs) does not exceed a threshold. And then, with the deduced channel capacity result, the per-node average throughput capacity of CWMN is derived based on two regular topologies, i.e. square topology and triangle topology. The simulation results indicate that the capacity is effectively improved with power control, and affected by topology, tolerated interference threshold, the number of cognitive users (CUs) and primary users (PUs).

Adaptive power loading with BER-constraint for OFDM systems

Abstract A novel adaptive power loading algorithm with the constraint of target overall bit error rate (BER) for orthogonal frequency division multiplexing (OFDM) systems is proposed in this article. The proposed algorithm aims to minimize the required transmit power with fixed data rate and uniform (nonadaptive) bit allocation, while guaranteeing the target overall BER. The power loading is based on the unequal-BER (UBER) strategy that allows unequal mean BERs on different subcarriers. The closed-form expressions for optimal BER and power distributions are derived in this article. Simulation results indicate the superiority of the proposed algorithm in terms of BER performance and algorithmic complexity.

Solving WDP in combinatorial double auction based on trading strategy

Abstract A solution for winner determination problem (WDP) in combinatorial double auction (CDA) was presented. Different from determining winner by solving optimization model which was non-deterministic polynomial (NP)-hard when the number of participants or resource types amounted to a large scale, the solution put the WDP goal–social welfare maximization into design of the trading strategy and determined winners by the process of resource allocation and pricing. In its corresponding allocation and pricing algorithm, sellers were allowed partially trading their bundles; the transaction path was approximated to Marshallian path; the utility for each winner was non-negative. Simulations show, compared to the WDP optimization model, the proposed algorithm can generate larger social welfare and it is particularly time efficient in conducting large-scale CDA.

Distributed interference suppression scheme for multi-cell uplink OFDMA system based on non-cooperative game

Abstract In this paper, a distributed interference suppression scheme is proposed for multi-cell uplink orthogonal frequency division multiple access (OFDMA) system. Firstly, we model resource allocation process as a non-cooperative game. Then we show the concept of Nash equilibrium (NE) and investigate its existence and uniqueness in detail. To enhance the performance of multi-cell OFDMA system, the further improvement process based on NE is given. Several adjustable parameters are set to make the system achieve different tradeoffs between the total capacity and complexity. Simulation results show that the proposed scheme can greatly improve the system performance comparing with conventional scheme.