WO2010030164A2

WO2010030164A2 - A base station for wireless network

Info

Publication number: WO2010030164A2
Application number: PCT/MY2009/000137
Authority: WO
Inventors: Abdelhaleem Saeed Rashid; Mohamad Hafizal; Mohd Ali Borhanuddin
Original assignee: Mimos Berhad
Priority date: 2008-09-09
Filing date: 2009-09-09
Publication date: 2010-03-18
Also published as: MY146401A; WO2010030164A3

Abstract

The present invention relates to a base station (100) for use in a wireless mesh network, whereby the physical (PHY) layer (400) of two wireless network standards is converged in the same layer.

Description

A Base Station for Wireless Network

Field of Invention

The present invention relates to a wireless network system, more particularly, the invention discloses a base station for a combination of at least two wireless network technologies, whereby interference within a wireless network system is minimal or reduced.

Background of Invention

Beneficial services offered by the wireless local area network (WLAN) connectivity have garnered the public attention and much has been written about them. The rapid demand for more enhanced technologies in the said wireless network resulting to the relevant contributors and innovators in the field to be on their toes and thus are constantly seeking to create value-added features or integration of features which are capable of providing a higher level of efficiency and convenience. Currently, there are wide varieties of standards which define the mode of operation for WLAN, be in the ad hoc or infrastructure. The most prominent wireless connectivity at present is WiFi (wireless fidelity) which operates based on IEEE 802.1 In, a dynamic protocol which allows a high speed wireless local area network (WLAN) connection for data transmission within wireless hotspots. It is known that there are several different versions of wireless systems that have advanced over time whereby the key differences include frequency band, type of wireless access, and maximum data transmission rates.

Another advancement of wireless network is WiMAX, whereby this high speed wireless wide area network (WWAN) technology takes wireless access to another level in regards to its capabilities as compared to WiFi. Typically WiFi and WiMAX deploy the IEEE 802.11 and IEEE 802.16 standards respectively, in which individually each of them provides high transmission rate in limited geographical coverage, while another offers more flexibility in addition to maintaining the technology's data rate and transmission range.

These versions of wireless technologies typically operate in the unlicensed frequency bands, which means there is no guarantee of peak or optimized performance due to possible interferences by other devices within the said frequency bands which are configured to operate in such a manner so that they are able to co-exist within the same area with minimal interferences with each other.

Although each of the above connection technologies has established its effectiveness amongst users and service providers even when deployed individually, research in regards to the complementary nature of WiMAX and WiFi has resulted to the emergence of network synergies for an optimized connectivity in more locations and capabilities. These technologies were found to complement each other relevance to eliminating the limited coverage range and providing high speed Internet access in wide area.

Accordingly with the combination of both technologies, users and service providers gain high speed wireless connectivity in more places or locations therefore creating a complete wireless solution for delivering high speed Internet access to businesses, homes and hot spots. Other significant characteristics of the combined network include extended coverage, cost reduction, optimized security and elevated range of broadband services.

It is known that as a result to a synergy of wireless technologies particularly for WiMAX and WiFi technologies, it would require said technologies to be located at the same base station (BS), this will help in the vertical handover (VHO) where the delay of handover will be less compared with the conventional WiMAX/WiFi heterogonous network with two different wireless Internet service providers (WISP). The combination of technologies would therefore lead to a handover operation, due to the establishment of the new link. For such operation, an adaptation layer is a necessity to avoid the need of multimedia gateway (MGW) in regards to the said handover.

While these known in the art systems providing such enhanced features are expedient for users of wireless networks including the service providers, users may find such services rather inadequate at some degree, be it in the operational perspective or convenience. An eminent downside in regards to the combined WiMAX and WiFi in the same device/BS is the severe interference problems as mentioned briefly in the preceding paragraphs, due to small spatial separation between antennas from both technologies; as both technologies utilize the same orthogonal frequency division multiplexing (OFDM) transmission technique. Such interferences include devices operating in the width band, which may include but not limiting to; microwave ovens, Bluetooth devices, baby monitors and cordless telephones. In many cases these interferences may reduce the transmission of data rates. The common types of interferences of devices include types which can be continuous, short-term intermittent or even short bursts, depending on the type of devices.

Following the interference problem as briefly described above, few prior art solutions are available but a great majority are provided for the media access control (MAC) layer perspective. As for the synergy of WiFi and WiMAX, the prior art solution may create or rather elevate WiFi/WiMAX base station complexity based on the apparent fact in the art that WiMAX and WiFi have completely different MAC structure. For instance, WiMAX MAC can share the channel among hundreds of users while providing QoS based on time division duplex (TDD) or frequency division duplex (FDD) (scheduled protocol) whereas WiFi MAC is contention-based based on the Carrier Sense Multiple Avoidance with Collision Avoidance (CSMA/CA) unscheduled protocol.

In another instance with respect to the prior art solutions as shown in FIG 1, co-located coexistence between WiMAX and WiEi utilizes IEEE 802.16 power save class (PSC) to create a non-interfering time periods of service operation opportunities for each radio operating in the same BS. The main function of the 802.16 power saving class for co- located coexistence is to not be deactivated during service operation. This feature can be advantageous in one aspect; nevertheless, this solution does not mitigate the interference predicament.

Recognizing the aforementioned shortcomings, the present invention has been accomplished to significantly provide ameliorating actions the BS could take to enhance the coexistence between WiFi and WiMAX radio co-located in the same BS. Preferably, in order to achieve a more enhanced coexistence of said technologies, clarifications and/or additions to IEEE 802.16 enabling MAC support for co-located coexistence with WiFi should be surfaced.

It is therefore the primary object of the present invention to provide a combination of networks in one WiFi/WiMAX base station with both WiFi and WiMAX technologies capabilities using orthogonal frequency division multiplexing (OFDM) technique, wherein with the system of the present invention, a solution for a primary drawback of the current systems is realized, in particular, with minimal interference.

In another embodiment of the present invention, there is provided a mesh network system base station comprising a physical layer solution with WiMAXAViFi physical layers is converged in the same layer, whereby the said physical layer operates using the same unlicensed frequency band. Summary of Invention

The present invention provides a base station (100) for a wireless mesh network, said base station (100) comprising at least one upper layer (102), at least one internet protocol layer (104), at least one adaptation layer (106), a first media access control (MAC) layer (108), a second media access control (MAC) layer (110) and a physical (PHY) layer; and a transmission convergence (TC) layer (418); wherein said physical layer (400) comprises a transmission convergence layer

(418); and a signal classification layer (419); characterized in that the physical (PHY) layer (400) comprising an OFDMA (402) extension section and an OFDM section (404); wherein the OFDM section (404) further comprises of an uplink unit (408) and a downlink unit (406); wherein the physical layer (PHY) layer is a converged layer for at least two wireless network standards.

Brief Description of the Drawings

This invention will be described by way of non-limiting embodiments of the present invention, with reference to the accompanying drawings, in which: The present invention which will be disclosed herein both as to organizational and method of operation, together with features, objects and advantages thereof may be best understood by reference to the following detailed description when read with accompanying drawings in which:

FIG 1 is the WiFi/WiMAX architecture in accordance to an embodiment of the present invention, prior to convergence;

FIG 2 shows the WiFi/WiMAX solution in accordance with the present invention whereby it is shown that the physical (PHY) for both WiFi and WiMAX are converged in one layer and with one radio frequency and antenna parts;

FIG 3 is a block diagram of the physical (PHY) layer structure in accordance with an embodiment of the present invention;

FIG 4 is a diagram showing the signals classification involved in one embodiment of the present invention.

Detailed Description of the Invention

In line with the above summary, the following description of a number of specific and alternative embodiments is provided to understand the inventive features of the present invention. It shall be apparent to one skilled in the art, however that this invention may be practiced without such specific details. Some of the details may not be described at length so as not to obscure the invention.

The present invention discloses a base station for a wireless mesh network, with reduced or minimal interferences as described in the preceding paragraphs. Suitably, the base station disclosed herein comprises a converged physical (PHY) layer of two WLAN standards,

It is known in the art that a physical (PHY) layer plays a major role in transmitting and receiving data in the form of packets, wirelessly.

FIG 1 shows the overall WiFi/WiMAX architecture prior to converging the physical layers (PHY) for both of the WiFi and WiMAX whereby it is shown that there are two separate physical (PHY) layers, each for WiMAX and WiFi respectively.

FIG 2 illustrates the overall converged physical layer (400) solution in accordance with the principles of the present invention, whereby Panel A is the protocol stack and Panel B is the board architecture including the WiFi/WiMAX physical (PHY) layer of the present invention. As seen in Panel A being the protocol stack, which may be found in many conventional systems, there is provided a plurality of upper layers (UL) (102) protocol, and internet protocol layer (104) (IP) mainly for providing an interface between different protocols, adaptation layer (106) for realizing protocol adaptations within the network, the MAC layers (108,110) each for WiMAX and WiFi, and the WiFi integrated or converged physical layer (PHY) (400). It is further noted that with the converged structure, the radio frequency (RF) and antenna parts can be reduced.

Accordingly and as shown in the functional block diagram referred herein as FIG 3, the WiFi/WiMAX physical layer structure (400) in accordance with an embodiment of the present invention, comprises the WiMAX MAC and WiFi MAC modules which are communicated to another two main sections, said sections are the downlink (DL) OFDM (406) section and the uplink (UL) OFDM section (408).

For the downlink (DL) OFDM section (404), the main components include the sub channelization, invert fast fourier transform (IFFT) and cyclic prefix insertion functions.

As opposed to the downlink (DL) OFDM section (406), the uplink (UL) OFDM section (408) comprises the cyclic prefix removal, fast fourier transform (FFT), and de- subchannelization functions.

There is further provided an orthogonal frequency -division multiple access (OFDMA) extension (402) which is solely configured for WiMAX, whilst the WiFi partially uses OFDM. It should be noted that the OFDMA technique is a combination of OFDM and multiple access parts. The said OFDMA extension (402) section includes symbol mapper and forward error correction (FEC) decoding, wherein it is understood by a person skilled in the art that the FEC decoding schemes may include Viterbi decoding, Turbo convolutional decoding, Turbo product decoding and Lower Direct Power Coding (LDPC) decoding.

Still referring to FIG 3, prior to the radio frequency (RF) unit, there are provided digital upconverters (DUCs) (410) and digital downconverters (DDCs) (412) , said DUCs (410) and DDCs (412) are positioned and thus communicates within the OFDM UL (408) and DL (406) sections. These converters utilize complex filter architectures including finite impulse response (FIR) and cascaded integrator-comb (CIC) filters.

The transmission convergence (TC) sublayer (418) is positioned to be in communication with the MAC layer and therefore is within the physical (PHY) layers. The primary role of the TC layer (418) is to transform variable length MAC protocol data units (PDUs) into the fixed length data blocks (i.e. WiMAX or WiFi), which may include a shortened block at the end of each burst. The TC layer (418) has predetermined sized PDU suitable to fit in the block currently being filled. It is noted that the MAC for WiMAX and WiFi communicates with the transmission convergence layer (TC) (418), including facilitating in providing a pointer indicating where the next MAC starts for example 802.16 MAC or 802.11 MAC which allows resynchronization to the next MAC packet date unit (PDU).

There is further provided a signal classification sublayer (SCS) (419) which is located in adjacent to the TC layer (418) and is also part of the physical (PHY) layer (400) as shown in FIG 3. The primary role of the said SCS layer (419) is for performing the task of signals classification as seen in FIG 4 prior to the resynchronization and data block resizing, which is performed by the TC layer (418). In this role, the SCS layer (419) therefore classifies or identifies each the signals received from the OFDMA or OFDM section (402, 404), wherein said layer (419) further determines as to whether each of the signals received is a WiMAX signal or a WiFi signal. Suitably, in order to accomplish the identification and classification tasks, each of the received signals from the OFDMA/OFDM section is correlated with a WiMAX reference template signal. In the event that the correlated signal is zero, it is confirmed that the signal is a WiMAX signal, thus the decision is communicated to the TC layer (418). If the correlation result is otherwise, the signal is therefore a WiFi signal. Conclusively, results of the determination or decisions based on the reference template signal are accordingly communicated to the TC layer (418).

As mentioned previously, FIG 4 provides the signals classification process involved for the converged structure. Upon completion of the said signal classification process, the TC layer (418) proceeds with the resynchronization and data block resizing as also explained in the preceding paragraphs.

It is noted from the principles and inventive embodiments of the present invention that the merging the physical layers of WiFi and WIMAX results to minimal interference, with an expanded radius range and elevated data transmission rate. While specific embodiments have been described and illustrated, it is understood that many changes, modifications, variations and combinations thereof could be made to the present invention without departing from the scope of the invention.

Claims

1. A base station (100) for a wireless network, said base station (100) comprising at least one upper layer (102), at least one internet protocol layer (104) , at least one adaptation layer (106) , a first media access control (MAC) layer

(108), a second media access control (MAC) layer (110) and a physical (PHY) layer (400); wherein said physical layer (400) comprises a transmission convergence layer (418); and a signal classification layer (419) ; characterized in that the physical (PHY) layer comprising an OFDMA (402) extension section and an OFDM section (404); wherein the OFDM section (404) further comprises of an uplink unit (408) and a downlink unit (406); wherein the physical layer (PHY) layer is a converged layer for at least two wireless network standards.

2. The base station (100) as claimed in Claim 1 wherein the TC Layer (418) of the physical (PHY) layer (400) is configured to perform the transformation of variable length data units into fixed length data blocks.

3. The base station (100) as claimed in Claim 1 wherein the SCS layer (419) of the physical (PHY) layer (400) is configured to perform the identification and classification of signals process, for signals received from the OFDMA/OFDM section (402, 404).

4. The base station (100) as claimed in Claim 1 to 3 wherein in the identification and classification of signals process, each of the received signals from the

OFDMA/OFDM section (402, 404) is correlated with a WiMAX reference template signal and decisions obtained based on said reference template is communicated to the transmission convergence (TC) layer (418).

5. The base station (100) as claimed in Claim 1 wherein the first media access control (MAC) layer (108) operates according to WiMAX standard.

6. The base station (100) as claimed in Claim 1 wherein the second media access control (MAC) layer (110) operates according to WiFi standard.

7. The base station (100) as claimed in Claim 1 wherein the transmission convergence layer (418) of the physical (PHY) layer (400) is in communication with the MAC layers (108, 110).

8. The base station (100) as claimed in Claim 1 wherein converged physical

(PHY) layer comprises the physical (PHY) layers for WiFi and WiMAX standards.

9. The base station (100) as claimed in Claim 1 wherein the physical (PHY) layer further includes a digital downconverter (DDC) (414) and a digital upconverter. (DUC) (412).

10. The base station (100) as claimed in Claim 1 wherein the OFDMA extension unit is configured solely for WiMAX standard.

11. The base station (100) as claimed in Claim 1 to 10 wherein the OFDMA extension section comprises a symbol mapper, symbol demapper and forward error correction (FEC) decoding scheme.

12. The base station (100) as claimed in Claim 1 to 11 wherein the transmission convergence layer (TC) (418) further comprises a predetermined sized protocol data unit (PDU).

13. The base station as claimed in Claim 1 to 12 wherein the transmission convergence layer (TC) (418) has variable protocol data units (PDU) with predetermined sizes to fit in the data blocks.

14. The base station as claimed in Claim 1 to 13 wherein the TC layer (418) is configured to facilitate in providing a pointer indicating where the next MAC starts (for WiMAX and WiFi) which therefore allows resynchronization to the next MAC PDU.