Abstract:
The method and apparatus of data communications for a transmitter in a millimeter wave network are provided. The method includes: generating a control physical layer (CPHY) preamble; generating a header, wherein the header includes a mode indicator; modulating and encoding a payload according to the mode indicator; generating a packet according to the control physical layer (CPHY) preamble, the header and the payload; and transmitting the packet.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Application claims priority of U.S. Provisional Patent Application No. 61/700,583, filed on Sep. 13, 2012, the entirety of which is incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention generally relates to data communications in a millimeter wave network, and more particularly, to the re-design of a header of a Control Physical layer (CPHY) for transmitting data. 
     2. Description of the Related Art 
     Millimeter wave (mmWave) technology allows for a new era in multigiga bits per second (bps) wireless communications for consumer electronics because of the huge available bandwidth worldwide. For example, 7 GHz (from 57-64 GHz) of unlicensed spectrum is available in the United State and Source Korea and 9 GHz of unlicensed spectrum is available in Europe. 
     The standards in 60 GHz wireless networks, such as the IEEE 802.11aj standard, IEEE 802.11ad, and Wireless Gigabit Alliance (WiGig), have been developed or are being developed by different industry consortiums and international standard organizations. The WiGig and IEEE 802.11ad standards are two promising standards with a majority of support from industry. It is very likely that the upcoming 802.11aj standard adopts the physical layer specification of the IEEEE 802.11ad standard. 
     In mmWave WPAN and IEEE 802.11ad, control PHY (CPHY) and data PHY (DPHY) are defined. In the Table 1, CPHY and Lowest rate DPHY transmit at very low data rates and are used for discovery mode. DPHY transmits at high data rates and is used for data communications. Generally, CPHY is operated in an omni-directional mode or quasi-omni directional mode and DPHY is operated in a directional mode. Therefore, DPHY requires higher signal-to-noise-ratio (SNR) than CPHY. For current mmWave WPAN based on the WiGig and IEEE 802.11ad standard, the minimum SNR requirement of DPHY is 12 dB (e.g. −1−(−13)=12 dB) higher than SNR required by CPHY, i.e. if the SNR difference of DPHY and CPHY is not higher than 12 dB, the DPHY may not work. The true SNR difference is limited by the size of the antenna array at the Space-Time Antenna (STA) and is defined by the condition: (True SNR difference)&lt;10*log 10  (number of antenna elements). Therefore, the STA must be equipped with an antenna array of more than 16 elements. 
     
       
         
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                 DATA 
                 Required 
               
               
                 TYPE 
                 MCS 
                 RATE 
                 SNR 
               
               
                   
               
             
             
               
                 CPHY 
                 DBPSK, ~½ code, Spreading 
                  27 Mbps 
                 −13 dB 
               
               
                   
                 32 
               
               
                 Lowest DPHY 
                 BPSK, ~½ code, Repetition 32 
                 385 Mbps 
                  −1 dB 
               
               
                   
               
             
          
         
       
     
     However, antenna arrays with a large number of antenna elements are not suitable for mobile devices due to size factor. Therefore, coverage problems may occur. For example, for a mobile device equipped with 4 antenna elements, SNR of the DPHY is just 6 dB (10 log 10 4˜6&lt;12) higher than the SNR of CPHY. Therefore, CPHY works fine but DPHY does not work. Namely, the mobile device can be associated with access point (AP) or personal basic service set central point (PBSS central point, PCP), but can&#39;t transmit/receive any data. 
     BRIEF SUMMARY OF THE INVENTION 
     Apparatuses and methods of data communications in millimeter wave network are provided to overcome the above mentioned problems. 
     An embodiment of the invention provides a method of data communications for a transmitter in a millimeter wave network, comprising: generating a control physical layer (CPHY) preamble; generating a header, wherein the header comprises a mode indicator; modulating and encoding a payload according to the mode indicator; generating a packet according to the control physical layer (CPHY) preamble, the header and the payload; and transmitting the packet. 
     An embodiment of the invention provides a method for data communications for a receiver in a millimeter wave network, comprising: receiving a packet; determining a type of the packet; determining a mode of the packet and demodulating and decoding the packet according to the mode of the received packet. 
     An embodiment of the invention provides a transmitter in a millimeter wave network, comprising: a preamble generator, configured to generate a control physical layer (CPHY) preamble; a header generator, configured to generate a header, wherein the header comprises a mode indicator; and a payload generator, modulating and encoding a payload according to the mode indicator. 
     An embodiment of the invention provides a receiver in a millimeter wave network, comprising: a preamble processor, configured to determine a type of a packet; a header processor, configured to determine a mode of the packet; and a decoder, configured to demodulate and decode the packet according to the mode of the packet. 
     Other aspects and features of the invention will become apparent to those with ordinary skill in the art upon review of the following descriptions of specific embodiments of communication transmission methods and systems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will become more fully understood by referring to the following detailed description with reference to the accompanying drawings, wherein: 
         FIG. 1  is a block diagram of a User Equipment (UE)  100  according to an embodiment of the invention; 
         FIG. 2  is a block diagram of a transmitter  120  according to an embodiment of the invention; 
         FIG. 3  is a schematic diagram of the packet according to an embodiment of the invention; 
         FIG. 4  is a block diagram of a receiver  130  according to an embodiment of the invention; 
         FIG. 5  is a flow chart illustrating the method of data communications for a transmitter in a millimeter wave network according to an embodiment of the invention; 
         FIG. 6  is a flow chart illustrating the method of data communications for a receiver in a millimeter wave network according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
       FIG. 1  is a block diagram of a User Equipment (UE)  100  according to an embodiment of the invention, wherein the UE  100  can be applied in a millimeter wave network based on the IEEE 802.11ad and/or IEEE 802.11aj specification. The UE  100  may be a mobile communications device, such as a cellular phone, a smart phone modem processor, a data card, a laptop stick, a mobile hotspot, an USB modem, a tablet, or others. The UE  100  comprises a processing unit  110 , a transmitter  120 , a receiver  130  and a memory device  140 , and an antenna module comprising at least one antenna. The processing unit  110  may be a general-purpose processor, or a Micro-Control Unit (MCU), or others, to execute the program codes stored in the memory device  140 . The transmitter  120  and the receiver  130  are connected with the antenna module to transmit/receive the wireless signals via the antenna. In some embodiments, the transmitter  120  and the receiver  130  may connect with or include a RF module (not present) to receive RF signals via the antenna and process the received RF signals to convert the received RF signals to baseband signals. The memory device  140  may be a volatile memory, e.g. a Random Access Memory (RAM), or a non-volatile memory, e.g. a flash memory, Read-Only Memory (ROM), or hard disk, or any combination thereof. Note that, in some embodiments of the invention, the user equipment  100  may further be extended to comprise more than one antenna and/or more than one radio module, and the invention should not be limited to what is shown in  FIG. 1 . 
       FIG. 2  is a block diagram of a transmitter  120  according to an embodiment of the invention. In  FIG. 2 , the transmitter  120  comprises a preamble generator  121 , header generator  122 , payload generator  123 . The preamble generator  121  is configured to generate a preamble S 1 , wherein the preamble S 1  is the same as a control physical layer (CPHY) preamble. In an embodiment, the preamble can follow the IEEE 802.11ad standard. The preamble S 1  comprises a Short Training Field (STF) and a Channel Estimation Field (CEF). The Short Training Field (STF) comprises  48  repetitions of the sequence Gb 128 ( n ) of length  128 , a sequence-Gb 128 ( n ) and a sequence-Ga 128 ( n ). The sequences Gb 128 ( n ) and Ga 128 ( n ) are Golay sequences defined in the WiGig specification and IEEE 802.11ad standard. The Channel Estimation Field (CEF) comprises two sequences Gu 512 ( n ), Gv 512 ( n ) of length  512  and a sequence Gv 128 ( n ) of length  128 . The sequences Gu 512 ( n ), Gv 512 ( n ) and Gv 128 ( n ) are also defined in the WiGig specification and IEEE 802.11ad standard. Note that since the STF in the data PHY adopts different Golay sequences, control PHY (CPHY) and data PHY (DPHY) can be detected according to the STF. 
     The header generator  122  comprises a scrambler  211 , a Low Density Parity Check (LDPC) encoder  212 , a DBPSK modulator  213 , and a spreader  214 . The header generator  122  is configured to generate a modified header S 2 , wherein the modified header S 2  comprises a mode indicator for indicating a plurality of Modulation Coding Scheme (MCS) modes. The modified header S 2  is scrambled by the scrambler  211 . The modified header S 2  is encoded by the LDPC encoder  212 . The modified header S 2  is modulated by the DBPSK modulator  213 . The modified header S 2  is spread with sequence Ga 32 ( n ) by the spreader  214 . Because the header generator  122  is similar to the CPHY header generator, the modified header is transmitted the same way as the CPHY header. However, the modified header S 2  re-defines the reserved bits of the CPHY header (presented MCS mode field of the Tables 2-3). Therefore, the MCS modes in the modified header S 2  are defined by setting the reserved bits of a CPHY header. In the general CPHY header, two reserved bits are defined according to the IEEE 802.11ad standard and they are only set to 0 in the CPHY header. 
     Table 2 is a schematic diagram of the modified header S 2  according to an embodiment. As shown in the Table 2, if the reserved bits are set to 0, it indicates an original CPHY mode (such as CPHY in Table 1). If the reserved bits are set to 1, the payload is modulated according to a first MCS mode. If the reserved bits are set to 2, the payload is modulated according to a second MCS mode, and if the reserved bits are set to 3, the payload is modulated according to a third MCS mode. 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                 Number of 
                 Starting 
                   
               
               
                 Field name 
                 Bits 
                 Bit 
                 Description 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Reserved 
                 1 
                 0 
                 Set to 0 (differential detector 
               
               
                   
                   
                   
                 initialization) 
               
               
                 Scrambler 
                 4 
                 1 
                 Bits of the initial scrambler state 
               
               
                 Initialization 
               
               
                 Length 
                 10 
                 5 
                 Number of date octets in the 
               
               
                   
                   
                   
                 PSDU. Range 14-1023 
               
               
                 Pack Type 
                 1 
                 15 
                 TRN packet type 
               
               
                 Training Length 
                 5 
                 16 
                 Length of the training field 
               
               
                 SIFS response 
                 1 
                 21 
                 Set to 1 if the STA is 
               
               
                   
                   
                   
                 transmitting a packet during an 
               
               
                   
                   
                   
                 SP or TXOP 
               
               
                 MCS mode 
                 2 
                 22 
                 Set to 0: CPHY, ignored by the 
               
               
                 (Reserved bits) 
                   
                   
                 receiver 
               
               
                   
                   
                   
                 Set to 1: first MCS mode 
               
               
                   
                   
                   
                 Set to 2: second MCS mode 
               
               
                   
                   
                   
                 Set to 3: third MCS mode 
               
               
                 HCS 
                 16 
                 24 
                 Header Check sequence 
               
               
                   
               
             
          
         
       
     
     Table 3 is a schematic diagram of the modified header S 2  according to another embodiment. In the Table 3. If the reserved bits are set to 0, it indicates an original CPHY mode (such as CPHY in Table 1). If the reserved bits are set to 1, the payload is modulated according to a first MCS mode. If the reserved bits have been set to 2, the payload is modulated according to a second MCS mode, and if the reserved bits have been set to 3, the reserved bits are reserved. 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                   
                 Number 
                   
                   
               
               
                   
                 of 
                 Starting 
               
               
                 Field name 
                 Bits 
                 Bit 
                 Description 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Reserved 
                 1 
                 0 
                 Set to 0 (differential detector 
               
               
                   
                   
                   
                 initialization) 
               
               
                 Scrambler 
                 4 
                 1 
                 Bits of the initial scrambler state 
               
               
                 Initialization 
               
               
                 Length 
                 10 
                 5 
                 Number of date octets in the 
               
               
                   
                   
                   
                 PSDU. Range 14-1023 
               
               
                 Pack Type 
                 1 
                 15 
                 TRN packet type 
               
               
                 Training Length 
                 5 
                 16 
                 Length of the training field 
               
               
                 SIFS response 
                 1 
                 21 
                 Set to 1 if the STA is transmitting 
               
               
                   
                   
                   
                 a packet during an SP or 
               
               
                   
                   
                   
                 TXOP 
               
               
                 MCS mode 
                 2 
                 22 
                 Set to 0: CPHY, ignored by the 
               
               
                 (Reserved bits) 
                   
                   
                 receiver 
               
               
                   
                   
                   
                 Set to 1: first MCS mode 
               
               
                   
                   
                   
                 Set to 2: second MCS mode 
               
               
                   
                   
                   
                 Set to 3: reserved 
               
               
                 HCS 
                 16 
                 24 
                 Header Check sequence 
               
               
                   
               
             
          
         
       
     
     The MCS modes, such as the first MCS mode, the second MCS mode and the third MCS mode, are selected from Table 4. For example, the first MCS mode may be R1, the second MCS mode may be R3, and the third MCS mode may be R5. Note the MCS modes in Table 2 are only taken as examples, and it is to be understood that the invention is not limited thereto. Those who are skilled in this technology can still use other parameters for different situations. 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                   
                   
                   
                 Spreading 
               
               
                 MCS 
                   
                   
                 sequence of 
               
               
                 mode 
                 Data Rate 
                 MCS mode 
                 length 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 R0 
                  54 Mbps 
                 DQPSK, ½ code, spreading ratio 32 
                 32 
               
               
                 R1 
                  54 Mbps 
                 DBPSK, ½ code, spreading ratio 16 
                 16 
               
               
                 R2 
                 108 Mbps 
                 DQPSK, ½ code, spreading ratio 16 
                 16 
               
               
                 R3 
                 108 Mbps 
                 DBPSK, ½ code, spreading ratio 8 
                 8 
               
               
                 R4 
                 216 Mbps 
                 DQPSK, ½ code, spreading ratio 8 
                 8 
               
               
                 R5 
                 216 Mbps 
                 DBPSK, ½ code, spreading ratio 4 
                 4 
               
               
                 R6 
                  54 Mbps 
                 QPSK, ½ code, spreading ratio 32 
                 32 
               
               
                 R7 
                  54 Mbps 
                 BPSK, ½ code, spreading ratio 16 
                 16 
               
               
                 R8 
                 108 Mbps 
                 QPSK, ½ code, spreading ratio 16 
                 16 
               
               
                 R9 
                 108 Mbps 
                 BPSK, ½ code, spreading ratio 8 
                 8 
               
               
                 R10 
                 216 Mbps 
                 QPSK, ½ code, spreading ratio 8 
                 8 
               
               
                   
               
             
          
         
       
     
     The payload generator  123  comprises a scrambler  215 , and an encoder  216 . The payload generator  123  is configured to scramble, modulate and encode the transmission data for generating a payload S 3  by the scrambler  215  and the encoder  216  according to one of the MCS modes defined in the modified header S 2 . The preamble S 1 , the modified header S 2  and the payload S 3  are combined to generate a packet or a frame.  FIG. 3  is a schematic diagram of the packet according to an embodiment of the invention. In the  FIG. 3 , the packet comprises the preamble S 1 , the modified header S 2  and the payload S 3 . 
       FIG. 4  is a block diagram of a receiver  130  according to an embodiment of the invention. In the  FIG. 3  the receiver  130  comprises a preamble processor  131  and a header processor  132 , a DPHY decoder  133 , and an Enhanced-CPHY decoder  134 . The preamble processor  131  is configured to determine the type of a received packet, such as CPHY, DPHY. As the above describes, because the STF in the DPHY adopts a different Golay sequence from the CPHY, the preamble processor  131  can determine the DPHY and CPHY according to the STF. If the received packet is DPHY, the received packet is transmitted to the DPHY decoder  133  and decoded by the DPHY decoder  133 . If the received packet is CPHY, the received packet is transmitted to the header processor  132 . The preamble processor  131  also provides estimated timing information, frequency offset, and channel information to the DPHY decoder  133  or header processor  132 . 
     The header processor  132  is configured to determine an MCS mode of the received packet, wherein the MCS mode is defined by setting the reserved bits of a CPHY header. Then, the Enhanced-CPHY decoder  134  may decode the received packet according to the MCS mode of the received packet. The Enhanced-CPHY decoder  134  is indicated for distinguishing from a general CPHY decoder. In an embodiment, the receiver  130  further comprises a general CPHY decoder. The general CPHY decoder may be combined with the Enhanced-CPHY decoder  134  or an independent device connected with the header processor  132 . If the header processor  132  determines that an MCS mode (Reserved bits) of the received packet is 0, the header processor  132  may transmit the received data to a general CPHY decoder. Otherwise (MCS mode is 1, 2 or 3), the header processor  132  may transmit the received data to the Enhanced-CPHY decoder  134 . 
     In an embodiment (such as Table 2), if the header processor  132  determines that the reserved bits have been set to 0, the Enhanced-CPHY decoder  134  demodulates the received packet by an original CPHY mode. If the header processor  132  determines that the reserved bits have been set to 1, the Enhanced-CPHY decoder  134  demodulates the received packet according to a first MCS mode. If the header processor  132  determines that the reserved bits have been set to 2, the Enhanced-CPHY decoder  134  demodulates the payload according to a second MCS mode. If the header processor  132  determines that the reserved bits have been set to 3, the Enhanced-CPHY decoder  134  demodulates the received packet according to a third MCS mode. In another embodiment (such as Table 3), if the header processor  132  determines that the reserved bits have been set to 0, the Enhanced-CPHY decoder  134  demodulates the received packet an original CPHY mode. If the header processor  132  determines that the reserved bits have been set to 1, the Enhanced-CPHY decoder  134  demodulates the received packet according to a first MCS mode. If the header processor  132  determines that the reserved bits have been set to 2, the Enhanced-CPHY decoder  134  demodulates the payload according to a second MCS mode, wherein in this embodiment, if the reserved bits have been set to 3, it means that the reserved bits are reserved. In an embodiment, if the header processor  132  determines that the reserved bits have been set to 0, the received packet may be demodulated by a general CPHY decoder. Otherwise (Reserved bits have been set to 1, 2 or 3), the received packet may be demodulated by the Enhanced-CPHY decoder  134 . 
       FIG. 5  is a flow chart illustrating the method of data communications for a transmitter in a millimeter wave network according to an embodiment of the invention. Firstly, in step S 510 , a CPHY preamble is generated. In an embodiment, the CPHY preamble can be an IEEE 802.11ad preamble. Then, in the step S 520 , a header is generated, wherein the header comprises a mode indicator. In the step S 530 , a payload is modulated and encoded according to the mode indicator. In the step S 540 , a packet is generated according to the control physical layer CPHY preamble, the header and the payload. In the step S 550 , the packet is transmitted by the transmitter. 
       FIG. 6  is a flow chart illustrating the method of data communications for a receiver in a millimeter wave network according to an embodiment of the invention. Firstly, in step S 610 , a received packet is received by the receiver. Then in the step S 620 , the type of the received packet is determined. If the type of the received packet is DPHY, the step S 630  is executed. In the step S 630 , the received packet is demodulated and decoded by the DPHY mode. If the type of the received packet is DPHY, the step S 640  is executed. In the step S 640 , the MCS mode of the received packet is determined. In the step S 650 , the received packet is demodulated and decoded according to the MCS mode of the received packet. 
     In the methods of the embodiments, coverage problems of a mobile device equipped with a small size array are eliminated. When the mobile device is equipped with a small size array, it can transmit data by modifying the general CPHY header rather than by the DPHY. In addition, in the receiver, different decoding schemes may be processed according to the type of the receive packet and the MCS mode of the received packet. 
     The steps of the method described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module (e.g., including executable instructions and related data) and other data may reside in a data memory such as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of computer-readable storage medium known in the art. A sample storage medium may be coupled to a machine such as, for example, a computer/processor (which may be referred to herein, for convenience, as a “processor”) such that the processor can read information (e.g., code) from and write information to the storage medium. A sample storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in user equipment. Alternatively, the processor and the storage medium may reside as discrete components in user equipment. Moreover, in some aspects any suitable computer-program product may comprise a computer-readable medium comprising codes relating to one or more of the aspects of the disclosure. In some aspects a computer program product may comprise packaging materials. 
     The above paragraphs describe many aspects. Obviously, the teaching of the invention can be accomplished by many methods, and any specific configurations or functions in the disclosed embodiments only present a representative condition. Those who are skilled in this technology can understand that all of the disclosed aspects in the invention can be applied independently or be incorporated. 
     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. Those who are skilled in this technology can still make various alterations and modifications without departing from the scope and spirit of this invention. Therefore, the scope of the present invention shall be defined and protected by the following claims and their equivalents.