WiMedia Alliance Research Articles

Distributed quality of service routing protocol for multimedia traffic in WiMedia networks

Ultra-wideband (UWB) technology has emerged as a solution for the wireless interface between medical sensors and personal servers in future telemedicine systems. The WiMedia Alliance has specified a distributed medium access control protocol based on UWB for high-rate WPANs. In the cases of some applications, data traffic between the source device and destination device is transmitted via one or more intermediate links before it reaches the destination device. However, when all data frames do not transmit in the current DRP reservation block, a relay device cannot transmit the received data frame from the source device in the current DRP policy, until the next DRP duration reserved for forwarding to the destination device begins. This policy increases end-to-end latency between the source device and destination device significantly. Therefore, in this paper, we propose a novel reservation-based routing protocol to minimize the end-to-end delay between source and destination. The proposed routing protocol utilizes the number of medium access slots and hop-count to decide the optimal route between the source device and destination device. The simulation results show that the proposed protocol can enhance the throughput and delay performance and improve energy efficiency by minimizing the packet drop and collision.

Providing an optimal QoS using demand-based distributed reservation protocol allocation algorithm for WiMedia medium access control

WiMedia Alliance, an industry association for supporting ultra-wide band plays a major role in personal area network. It handles high volume of data for multimedia applications such as construction of home networks, establishment of virtual multimedia connectivity for video or audio sharing, etc. Since quality of service has its own impact in wireless networking domain, we tried to investigate the effect of allocating medium access slot by considering mobility and link quality. We also present an optimal utilisation of bandwidth in a highly contented environment along with a suitable mechanism for scheduling of medium access slots in an effective manner. The performance analysis of the proposed algorithm was tested using OmNet++. The results were promising in terms of improvement delay, throughput and packet drop ratio.

A Contention Delay Minimization Scheme in WiMedia Networks

Ultra wideband (UWB) technology has emerged as a solution for the wireless interface between medical sensors and a personal server in future telemedicine systems. The WiMedia Alliance has specified a distributed medium access control protocol based on UWB for high-rate WPANs. Because WiMedia devices transmit data frames using CSMA/CA in PCA duration, waste of time slot interval occurs by collision, and data transmission and the overall throughput is decreased. Therefore, we propose medium access scheme to improve conflict and channel waste and to minimize contention by using own beacon slot number and neighbor's beacon slot number. Simulation results have shown that the proposed scheme has excellent performance in terms of throughput, delay, jitter, and fairness.

Channel State Information Based Distributed Reservation Protocol for Energy Efficiency in WiMedia Networks

Ultra wideband (UWB) technology has emerged as a solution for the wireless interface between medical sensors and a personal server in future telemedicine systems. The WiMedia Alliance has specified a distributed medium access control protocol based on UWB for high-rate wireless personal area networks. The legacy WiMedia standard must statically reserve an additional transmission time of 30 %, since transmission time is limited to network environment in wireless network. When channel environment is deteriorating badly, the additional reservation may not have enough time. Because the legacy WiMedia standard must wait the next reservation period if sending device does not transmit data frames in the current reservation period, the transmission delay occurs. Also, in a good channel environment, the additional reservation time results in a waste of performance. Therefore, there is a need to provide the reliability of data transmission as sending device predicts channel environment in WiMedia network and reserves the distributed reservation protocol (DRP) reservation duration considering the estimated channel environment. In this paper, we propose a novel resource reservation scheme considering channel environment in WiMedia network. The simulation results show that proposed protocol can enhance the throughput and delay performance and improve energy efficiency by minimizing the idle period of DRP reservation block.

A Robust Beacon Scheduling Scheme for Coexistence Between UWB Based WBAN and WiMedia Networks

Ultra wideband (UWB) technology has emerged as a solution for the wireless interface between medical sensors and a personal server in future telemedicine systems. The WiMedia Alliance has specified a distributed medium access control (D-MAC) protocol based on UWB for high-rate wireless personal area networks (WPANs). Also, the IEEE 802.15.6 standard for wireless body area networks (WBANs) allows that devices for healthcare and lifestyle applications are placed around and within the body. However, current WBAN devices cannot coexist with other home network systems or WPAN systems and cannot share wireless channel with the existing WiMedia devices, efficiently. Existing researches about coexistence are not suitable for WiMedia MAC protocol based on distributed architecture, since they focused on MAC protocol based on centralized architecture. Therefore, in this paper, we propose a robust beacon scheduling scheme for coexistence between UWB based WBAN and WiMedia networks. Using proposed scheme, WBAN devices can share the resource more efficiently with WiMedia devices and exchange data frames through the reserved BAN period duration.

A Fair and QoS-Aware Resource Allocation Scheme in UWB WPANs with WiMedia Distributed MAC

Merits of distributed medium access control specified by WiMedia Alliance such as distributed nature and high data rate make it a favorite candidate standard for high rate wireless personal area network. However, the current WiMedia MAC standard has not considered supporting Quality of Service (QoS) even though QoS parameters such as a range of service rates are provided to each traffic stream (TS). Therefore, we propose a fair and QoS-aware resource allocation method that provides a fair and maximized QoS for all TSs according to the current traffic load condition and differentiates SoQ among different QoS classes while guaranteeing fairness of SoQ within a QoS class in a fully distributed manner. Even in case that the traffic load varies, each device independently recognizes the changes and calculates fair and maximum allowable service rates for TSs. From the simulation results, it is proven that the proposed method achieves high capacity of TSs and fair QoS provisioning under various traffic load conditions.

WiMedia D-MAC 기반 Wireless USB 시스템을 위한 SoQ-based 릴레이 통신 프로토콜

The WiMedia Alliance has specified a Distributed Medium Access Control (D-MAC) protocol based on UWB for high speed wireless home networks and WPANs. In this paper, firstly, the fair SoQ-based Distributed Reservation Protocol (DRP) for D-MAC is analyzed. And a novel SoQ-based relay transmission protocol is proposed to overcome DRP conflicts fast. In the proposed protocol, each device executes the Satisfaction of QoS (SoQ) time slot allocation algorithm independently. And, in order to give the loser device due to DRP conflicts another chance to maintain QoS resources, the proposed relay transmission protocol helps the device reserve another indirect link maintaining the required QoS resources via a relay node.

Cross-layer multiple-access optimization scheme for linear precoded OFDM UWB systems

With the growing demand for new wireless applications accompanied with high expectations for better QoS fulfillment especially for multimedia and real-time applications, the performance of the radio resource management in a multiuser context is ensured by the ability to provide an efficient and optimized spectrum sharing scheme that should respect the wireless channel conditions and satisfy the different users’ demands. From the physical layer perspective, metrics such as spectrum efficiency and minimum BER are the most important criteria to be considered. On the other hand, from a user perspective, QoS as well as fairness among the competing users are the main metrics because they determine how much end-users are satisfied and how efficient the available resources are shared among the existing users. Based on the use of the linear precoded orthogonal frequency division multiplexing (LP-OFDM) solution proposed as an evolution of the well-known multiband OFDM (MB-OFDM) solution supported by the WiMedia Alliance for future high-rate ultra-wideband (UWB) systems, the objective of this paper is twofold. First, we study a multiuser optimization spectrum sharing scheme for LP-OFDM systems. Second, based on the optimization study, we define a novel multiple-access solution which jointly considers the frequency resource allocation and the time scheduling for the high-rate LP-OFDM UWB systems. Simulation results demonstrate the efficiency of the use of the LP-OFDM transmission technique in the multiuser spectrum sharing scheme. Besides, the novel multiuser time–frequency sharing scheme shows its capacity to provide a high performance level for high-priority users.

와이미디어 통신네트워크의 멀티미디어 QoS 개선을 위한 분산협력방식 MAC 프로토콜 성능분석

In this paper, an efficient technique for enhancing the QoS of multimedia service for an WiMedia network applying distributed cooperative medium access (D-MAC) protocol is proposed. D-MAC protocol has been proposed to support high-rate Wireless Personal Area Networks (HR-WPANs) by the WiMedia Alliance. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia supports all devices to be self-organized and removes the SOP (Simultaneous Operating Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However the WiMedia D-MAC can`t prevent reduce the throughput degradation occurred by mobile nodes with low data rate. Therefore, a distributed cooperative MAC protocol for multi-hop UWB network is proposed in this paper. The proposed technique can intelligently select the transmission path with higher data rate to provide real-time multimedia services with minimum delay, thus enhances QoS of multimedia service.

WiMedia Distributed MAC 통신 시스템에서 QoS 성능 향상을 위한 릴레이 통신 프로토콜

본 논문에서는 UWB 기술 기반 WiMedia 무선 USB Distributed Medium Access Control (D-MAC) 프로토콜의 공평하고 분산적인 SoQ기반 Distributed Reservation Protocol (DRP) 타임슬롯 자원 할당 방법의 성능을 분석하고, DRP 예약 충돌을 회피하기 위해 릴레이 통신 기술을 적용한 SoQ 릴레이 전송 프로토콜을 제안한다. 본 논문에서 제안하는 SoQ 릴레이 전송 프로토콜은 Satisfaction of QoS (SoQ) 알고리즘을 각 단말 디바이스에서 분산적으로 실행하고, 충돌대상 디바이스에게 예약된 QoS 자원을 유지할 수 있도록 Direct Link 뿐만 아니라 릴레이 노드를 경유하여 또 다른 Indirect Link 링크를 예약할 수 있는 자원 예약 프로토콜을 제안한다. The WiMedia Alliance has specified a Distributed Medium Access Control (D-MAC) protocol based on UWB for high speed wireless home networks and Wireless USB. In this paper, firstly, the fair SoQ-based Distributed Reservation Protocol (DRP) for D-MAC is analyzed. And a novel SoQ-based relay transmission protocol is proposed to overcome DRP conflicts fast. In the proposed protocol, each device executes the Satisfaction of QoS (SoQ) time slot allocation algorithm independently. And, in order to give the loser device due to DRP conflicts another chance to maintain QoS resources, the proposed relay transmission protocol helps the device reserve another indirect link maintaining the required QoS resources via a relay node.

A Distributed Cooperative MAC Protocol for QoS Improvement and Mobility Support in WiMedia Networks

A Distributed Medium Access Control (D-MAC) protocol based on UWB for high-rate Wireless Personal Area Networks is specified by the WiMedia Alliance. D-MAC protocol is suitable for ubiquitous connection in home networks, military/medical applications due to its inexpensive cost, low power consumption, high data rate, and distributed approach. In contrast to IEEE 802.15.3, D-MAC makes all devices have the same functionality. And its networks are self-organized and provide devices with functions such as access to the medium, channel allocation to devices, data transmission, quality of service and synchronization in a distributed manner. D-MAC fundamentally removes the problems of the centralized MAC approach revealed at IEEE 802.15.3 MAC by adopting a distributed architecture. However, the current D-MAC can't prevent QoS degradations, occurred by mobile nodes with low data rate due to bad channel status, which cause critical problems in QoS provisioning to isochronous streams and mobile applications. Therefore, we propose a distributed cooperative MAC protocol for multi-hop WiMedia networks using virtual MIMO links. Based on instantaneous Channel State Information among WiMedia devices, our proposed protocol can intelligently select the transmission path with higher data rate to provide advanced QoS with minimum delay for real-time multimedia streaming services.

UWB 기반 Distributed MAC 시스템을 위한 SoQ 기반 협력 통신 프로토콜 설계

본 논문에서는 UWB 기술 기반 WiMedia Distributed Medium Access Control (D-MAC) 무선 USB 표준 프로토콜에 적용할 수 있는 Satisfaction of QoS (SoQ) 기반 협력 통신 프로토콜을 제안한다. 이를 위해 UWB 링크 전송 속도와 QoS 척도에 따른 릴레이 노드 선정 알고리즘을 제안한다. 본 논문에서 제안하는 SoQ 기반 협력 통신 프로토콜은 분산적인 D-MAC 무선 USB 표준 기술과 호환성을 갖고, 각 디바이스에서 독립적으로 실행되는 SoQ 기반 Relay Node Selection (RNS) 기준에 따라 실행된다. The WiMedia Alliance has specified a Distributed Medium Access Control (D-MAC)/WUSB protocol based on UWB for high speed wireless home networks and WPANs. In this paper, we propose a novel SoQ-based cooperative communication protocol adaptive to current UWB link transmission rate and QoS measure. The proposed SoQ-based cooperative communication protocol has compatibility with current WiMedia D-MAC/Wireless USB standard and is executed at each device according to a SoQ-based Relay Node Selection (RNS) criterion.

UWB 기반 Distributed MAC 시스템을 위한 협력 통신 프로토콜 설계

본 논문에서는 UWB 기술 기반 WiMedia Distributed Medium Access Control (D-MAC) 표준 프로토콜에 적용할 수 있는 협력 통신 프로토콜을 제안한다. 이를 위해 무선 채널 상태에 따라 변화하는 UWB 링크 전송 속도에 적응적인 릴레이 노드 선정 알고리즘을 제안한다. 본 논문에서 제안하는 UWB 링크에 적응적인 릴레이 통신 프로토콜은 분산적인 D-MAC 표준 기술 및 무선 USB 기술과 호환성을 갖고, 각 디바이스에서 독립적으로 실행되는 Relay Node Selection (RNS) 기준에 따라 실행된다. The WiMedia Alliance has specified a Distributed Medium Access Control (D-MAC) protocol based on UWB for high speed wireless home networks and WPANs. In this paper, we propose a novel cooperative communication protocol adaptive to current UWB link transmission rate. The proposed cooperative communication protocol has compatibility with current WiMedia D-MAC and Wireless USB standard and is executed at each device according to a Relay Node Selection (RNS) criterion.

WiMedia Distributed MAC 통신 시스템을 위한 UWB 링크에 적응적인 릴레이 통신 프로토콜

The WiMedia Alliance has specified a Distributed Medium Access Control (D-MAC) protocol based on UWB for high speed wireless home networks and WPANs. In this paper, firstly, a time slot reservation protocol for relay transmission is proposed. Furthermore, we propose a novel relay node selection algorithm adaptive to current UWB link transmission rate. The proposed relay node selection algorithm has compatibility with current WiMedia D-MAC standard and is executed at each device according to the SoQ as a QoS criterion.

Gigabit UWB video transmission system for wireless video area network

Ultra-wideband (UWB) technology has offered a large application bandwidth which has been reached up to 1 Gb/s recently. One of various UWB specifications, medium access control (MAC) and physical layer (PHY) technologies of WiMedia Alliance can also be used for high speed multimedia applications to establish a wireless video area network (WVAN). In this paper, we propose a Gb/s UWB video transmission system for WVANs. In order to verify the possibilities of Gb/s wireless transmission of multiple video streams, we first built an analysis model and a simulation model. Then we implemented a hardware-based traffic processing block and a Gb/s wireless MAC accelerator. Using the proposed Gb/s video transmission system, we can transmit high definition video streams to several tens of users while guaranteeing quality of service.

Frequency-selective fading of ultrawideband wireless channels in confined environments

As a result of the recent ruling by the European Commission, ultrawideband (UWB) wireless communications can now pervade small confined environments such as cars or trains. This research studies frequency-selective fading experienced by UWB wireless channels in these confined environments. It focuses on the relationship between the severity of fading and the environment size using analytical modelling, simulation and measurement. The authors show that the frequency-selective fading is more severe in smaller environments because the bandwidth required to resolve all multipaths in time is inversely proportional to the cubic root of the volume of the environment. They show that the European Computer Manufacturers Association (ECMA) International standards for UWB proposed by the WiMedia alliance may not provide sufficient means of mitigating the issues associated with the frequency-selective fading in confined environments such as cars.

A Distributed Approach of Proportional Bandwidth Allocation for Real-Time Services in UltraWideBand (UWB) WPANs

Quality of service (QoS) provisioning is one of the most important criteria in newly emerging UWB WPANs, as they are expected to support a wide variety of applications from time-constrained, multimedia streaming to throughput-hungry, content transfer applications. Recently, the WiMedia Alliance has announced the PHY/MAC specification together with the common radio platform for UWB WPANs. The WiMedia MAC uses the contention-free reservation-based access, which supports isochronous traffic with distributed reservation protocol (DRP), and the contention-based access, which provides service differentiation for best effort and variable-rate real-time traffic with prioritized channel access (PCA), similar to the enhanced distributed coordinated access (EDCA) in IEEE 802.11e. In this paper, we conduct a comprehensive theoretical analysis and show that with the currently recommended parameter setting, EDCA cannot provide adequate QoS. In particular, without responding to the system dynamics (e.g., taking account of the number of active stations in each class), EDCA cannot allocate bandwidth in a deterministic proportional manner and the system bandwidth is underutilized. After identifying the deficiency of EDCA, we propose an enhanced QoS-provisioning framework for the PCA scheme that dynamically controls channel access to adjust allocated bandwidth depending on the change of application's bit rate, i.e., variable-rate real-time traffic. We show that in this framework, 1) variable-rate real-time traffic is adaptively guaranteed of deterministic bandwidth via a contention-based reservation access method; 2) best effort traffic is provided with deterministic proportional QoS; and 3) moreover, the bandwidth utilization in PCA is maximized. By deterministic proportional QoS, we mean that the proposed protocol will maintain the ratio, rj, of per-station throughput attained by a station of class j to that attained by a station of class 1 at the targeted value, and yet, the real amount of network bandwidth is changing according to the current available network bandwidth. We have also validated and evaluated the QoS provisioning capability and practicality of the proposed PCA framework both via simulation and an empirical study with the Multiband Atheros Driver for WiFi (MADWifi) Linux driver for Wireless LAN devices with the Atheros chipset.

A disturbed resource reservation structure for mobility and QoS support in WiMedia networks

A Distributed Meduim Access Control (D-MAC) protocol had been proposed to support High Rate Wireless Personal Area Networks (HR-WPANs) by the WiMedia Alliance. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia Alliance supports DRP (Distributed Reservation Protocol) mechanism which makes all devices be self-organized and removes the SOP (Simultaneous Operation Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However, since each device's mobility perspective in multi-hop environment has not been taken into account in the current WiMedia D-MAC, it may cause a hidden node problem. In addition, once a DRP conflict occurs due to the mobile hidden node problem, only one of the DRP reservations involved in that DRP conflict maintains the reserved MASs, while other DRP reservations must be terminated and DRP negotiations for them have to be restarted although only a few Mass are overlapped. Such DRP termination and renegotiation time delays due to the DRP conflicts can be a critical problem to the mobile devices transceiving real-time QoS traffic streams. Therefore, we propose a mecahnism to provent and resolve multi-hop range DRP conflicts due to each device's mobility in D-MAC environment.

A Multi-Hop Resource Reservation Scheme for Seamless Real-Time QoS Guarantee in WiMedia Distributed MAC Protocol

In this paper, a multi-hop range conflict-free resource reservation scheme for UWB (Ultra Wide Band) WPAN (Wireless Personal Area Network) with D-MAC (Distributed Medium Access Control) is proposed. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia Alliance supports DRP (Distributed Reservation Protocol) mechanism which makes all devices be self-organized and removes the SOP (Simultaneous Operating Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However, since each device's mobility perspective in multi-hop environment has not been taken into account in the current WiMedia D-MAC, it may cause a "mobile" hidden node problem. In addition, once a DRP conflict occurs due to the mobile hidden node problem, only one of the DRP reservations involved in that DRP conflict maintains the reserved MASs, while the other DRP reservations must be terminated and DRP negotiations for them have to be re-started although only a few MASs are overlapped. Such DRP termination and renegotiation time delays due to the DRP conflicts can be a critical problem to the mobile devices transceiving real-time QoS traffic streams. Therefore, we propose a mechanism to prevent and resolve multi-hop range DRP conflicts due to each device's mobility in D-MAC environment and demonstrate its guaranteed Seamless QoS and prioritized real-time QoS performances via numerical analyses.

A fair distributed resource allocation method in UWB wireless PANs with WiMedia MAC

The WiMedia alliance has specified a distributed medium access control (WiMedia MAC) protocol based on ultra wideband (UWB) for high data rate WPANs (HR-WPANs). The merits of WiMedia MAC such as distributed nature and high data rate make it a favorite candidate in HR-WPAN. Although QoS parameters such as the range of service rates are provided to a traffic stream, the WiMedia MAC is not able to use the QoS parameters and to determine or adjust a service rate using the QoS parameters for the traffic stream. In this paper, we propose a fair and adaptive resource allocation method that allocates time slots to isochronous streams according to QoS parameters and the current traffic load condition in a fully distributed manner. Although the traffic load condition changes, each device independently recognizes the changes and calculates fair and maximum allowable service rates for traffic streams. From the numerical and simulation results, it is proved that the proposed method achieves high capacity of traffic streams and fair QoS provisioning under various traffic load condition.